A GUIDELINE ON OFFICE AUTOMATION SECURITY
5 DECEMBER 1986
EXECUTIVE SUMMARY
Office Automation Systems (OA systems) are small, microprocessor-
based Automated Information Systems that are used for such functions
as typing, filing, calculating, sending and receiving electronic
mail, and other data processing tasks. They are becoming commonly
used by managers, technical employees, and clerical employees to
increase efficiency and productivity. Examples of OA systems
include personal computers, word processors, and file servers.
This guideline provides security guidance to users of OA systems, to
the ADP System Security Officers responsible for their operational
security, and to others who are responsible for the security of an
OA system or its magnetic storage media at some point during its
life-cycle.
This guideline explains how OA system security issues differ from
those associated with mainframe computers. It discusses some of the
threats and vulnerabilities of OA systems, and some of the security
controls that can be used. It also discusses some of the
environmental considerations necessary for the safe, secure
operation of an OA system.
This guideline suggests some security responsibilities of OA system
users, and of ADP System Security Officers. Also described are some
of the security responsibilities of the organization that owns or
leases the OA system.
In addition, guidance is given to the procurement officer who must
purchase OA systems or components, and guidance is also provided to
the officer who is responsible for securely disposing of OA systems,
components, or the associated magnetic media.
This document is issued as a National Telecommunications and
Information Systems Security Advisory Memorandum, and is therefore
intended as guidance only. Nothing in this guideline should be
construed as encouraging or permitting the circumvention of existing
Federal Government or organizational policies.
TABLE OF CONTENTS
PART I: INTRODUCTION
1.O INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Purpose and Scope . . . . . . . . . . . . . . . . . . . 3
1.2 Structure . . . . . . . . . . . . . . . . . . . . . . . 3
2.0 THE OFFICE AUTOMATION SECURITY PROBLEM . . . . . . . . . . . . . 5
2.1 Protecting Information From Unauthorized
Personnel . . . . . . . . . . . . . . . . . . . . 5
2.2 Sensitivity Levels of Magnetic Media. . . . . . . . . . 6
2.3 OA Systems With Fixed Media vs. OA Systems With
Removable Media . . . . . . . . . . . . . . . . . 7
PART II: GUIDANCE FOR THE OFFICE AUTOMATION SYSTEM USER
3.0 RESPONSIBILITIES OF OA SYSTEM USERS . .. . . . . . . . . . . . . 11
4.0 OPERATIONAL SECURITY FOR STAND-ALONE OFFICE AUTOMATION
SYSTEMS. . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1 OA Systems With Removable Media Only. . . . . . . . . . 12
4.2 OA Systems With Fixed Media . . . . . . . . . . . . . . 17
5.0 OPERATIONAL SECURITY FOR CONNECTED OFFICE AUTOMATION
SYSTEMS. . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1 Using an OA System as a Terminal
Connected to Another Automated Information System 21
5.2 OA Systems Used as Hosts on Local
Area Networks . . . . . . . . . . . . . . . . . . 22
PART III: GUIDANCE FOR ADP SYSTEM SECURITY OFFICERS
6.0 RESPONSIBILITIES OF THE ADPSSO . . . . . . . . . . . . . . . . . 27
7.0 THREATS, VULNERABILITIES, AND CONTROLS . . . . . . . . . . . . . 28
7.1 Threats, Vulnerabilities, and Controls: an Overview . 28
7.2 Physical and Personnel Security . . . . . . . . . . . . 29
7.3 Communications Security . . . . . . . . . . . . . . . . 31
7.4 Emanations Security . . . . . . . . . . . . . . . . . . 32
7.5 Hardware/Software Security. . . . . . . . . . . . . . . 32
7.6 Magnetic Media. . . . . . . . . . . . . . . . . . . . . 34
7.7 Environmental Considerations. . . . . . . . . . . . . . 36
7.8 Preparing Downgraded Extracts . . . . . . . . . . . . . 38
PART IV: GUIDANCE FOR OTHERS
8.0 RESPONSIBILITIES OF THE ORGANIZATION OWNING THE OA SYSTEM . . . 41
9.0 REQUIRING SECURITY IN THE PROCUREMENT OF OFFICE AUTOMATION
SYSTEMS. . . . . . . . . . . . . . . . . . . . . . . . . . . 43
9.1 Processing Classified Information:
Policy Requirements . . . . . . . . . . . . . . . 43
9.2 Physical Environment of the OA System . . . . . . . . . 44
9.3 Identification of Non-Volatile Components . . . . . . . 44
9.4 System Communications Capabilities. . . . . . . . . . . 44
9.5 Shared-Use Systems and Multi-User Systems . . . . . . . 45
10.0 SECURE DISPOSAL OF OFFICE AUTOMATION SYSTEMS. . . . . . . . . 47
10.1 Removable Media . . . . . . . . . . . . . . . . . . . . . . 47
10.2 Fixed Media . . . . . . . . . . . . . . . . . . . . . . 47
10.3 The Remainder of the OA System . . . . . . . . . . . . 47
APPENDIX: A Guideline on Sensitivity Marking of the Office
Automation System and Its Storage Media . . . . . 49
LIST OF ACRONYMS. . . . . . . . . . . . . . . . . . . . . . . . . 53
GLOSSARY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
REFERENCES. . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
PART I:
INTRODUCTION
1.0 INTRODUCTION
In recent years, there has been a tremendous increase in the number of
Federal Government personnel using Automated Information Systems (AIS)
to help with their jobs. In a large number of cases, the AIS involved
are small, microprocessor-based systems referred to as "Office
Automation Systems," or "OA Systems," for short. These OA Systems can
increase efficiency and productivity of those whose jobs include such
functions as typing, filing, calculating, and sending and receiving
electronic mail. In addition, these systems can be used by technical
and other personnel to performs functions such as computing and data
processing.
When used wisely, OA Systems can be a boon to the office worker and
the engineer alike, helping to get more work done in less time. Not
using them in a secure manner, however, can result in the compromise,
improper modification, or destruction of classified or sensitive, but
unclassified, information (as defined in NTISSP No. 2[18]). It is
therefore necessary that OA System users be made aware of: (1)
procedures and practices which will aid in the secure usage of these
systems, and (2) the consequences of not employing security measures.
The objective of this guideline is to address these two issues in the
context of protecting classified or sensitive, but unclassified,
information.
1.1 Purpose and Scope
This document provides guidance to users, managers, security officers,
and procurement officers of Office Automation Systems. Areas
addressed include: physical security, personnel security, procedural
security, hardware/software security, emanations security (TEMPEST),
and communications security for stand-alone OA Systems, OA Systems
used as terminals connected to mainframe computer systems, and OA
Systems used as hosts in a Local Area Network (LAN). Differentiation
is made between those Office Automation Systems equipped with
removable storage media only (e.g., floppy disks, cassette tapes,
removable hard disks) and those Office Automation Systems equipped
with fixed media (e.g., Winchester disks).
1.2 Structure
This guideline is divided into four parts, which are further
subdivided into a total of ten chapters. Part I is the introductory
part of this guideline. Chapter 1 gives an introduction, while
Chapter 2 discusses the Office Automation security problem and why it
is different from security problems involving larger Automated
Information Systems.
Part II provides guidance to the users of OA Systems. Chapter 3
details some security responsibilities of all OA System users.
Chapter 4 provides guidance to users of stand-alone OA Systems, while
Chapter 5 provides guidance to users of connected OA Systems.
Part III provides guidance to those ADP System Security Officers
(ADPSSO) who are responsible for the security of OA systems. (Note:
throughout this document, the term "security officer" will be used to
mean ADPSSO.) Chapter 6 describes some of the responsibilities of
security officers. Chapter 7 details some of the threats,
vulnerabilities and security controls associated with Office
Automation Systems.
Part IV provides guidance to others associated with OA Systems.
Chapter 8 is a discussion of some of the security responsibilities
incumbent upon the organization that owns an OA System. Chapter 9
provides guidance to procurement officers about addressing security
during the procurement phase of the OA System life-cycle. Chapter 10
provides guidance concerning the disposal of Office Automation Systems
and/or their components.
There is an Appendix that discusses security markings for the OA
System and media used in it, a List of Acronyms that gives expansions
for acronyms used in this guideline, and a Glossary that defines terms
used in this document.
2.0 THE OFFICE AUTOMATION SECURITY PROBLEM
There are three major points to remember about Office Automation
Systems when considering security of these systems throughout their
life-cycle. These points are:
(1) Most current Office Automation Systems do not provide the
hardware/software controls necessary to protect information from
anyone who gains physical access to the system. Therefore, the most
effective security measures to be used with these systems are
appropriate physical, personnel, and procedural controls.
(2) All information stored on a volume of magnetic media (e.g.,
floppy disk, cassette tape, fixed disk) should be considered to have
the same sensitivity level. This level should be at least as
restrictive as the highest sensitivity level of any information
contained on the volume of media.
(3) There are different security considerations for OA Systems with
fixed media versus those with removable-media-only.
2.1 Protecting Information From Unauthorized Personnel
United States Government policy requires that classified information
not be given to an individual unless he or she has the required
clearance and needs the information for the performance of the
job*[6,20]. For sensitive, but unclassified, information, no
clearance is required; therefore, all access is based solely on need-
to-know[20]. These policies must be enforced for information
contained within OA Systems as well as for all other information.
Therefore, information contained in OA Systems must be protected from
compromise, unauthorized modification, and destruction.
Most current Office Automation Systems processing classified or
sensitive, but unclassified, information do not provide sufficient
hardware/software security controls to prevent a user from accessing
information stored anywhere in the system. Simply put, most current
OA Systems are based on microprocessors that do not support multiple
hardware states. In almost all cases, multiple hardware states are
necessary to identify users, limit their actions, or keep them from
accessing information for which they are not authorized. (See Section
7.5 of this document for a detailed discussion of this problem.)
____________
* Bracketed numbers correspond to References, p. 57
In fact, at the time of this writing, no Office Automation Systems
have been certified as meeting even the class C1 requirements listed
in the Department of Defense Trusted Computer System Evaluation
Criteria[2], (hereafter known as the TCSEC).
Because of the lack of adequate hardware/software security, proper
physical, procedural, and personnel access controls must be used to
prevent personnel from accessing the system while it contains any
information (either in memory or on resident media) for which they are
not authorized.
2.2 Sensitivity Levels of Magnetic Media
All information contained on a volume of magnetic storage media should
be considered to have the same sensitivity level. This sensitivity
level should be at least as restrictive as the highest sensitivity
level of any information contained on the media.
The reason for this requirement is simple: under ordinary
circumstances, a user of an OA System has no way of knowing exactly
what is written where on a volume of media. It is possible that there
have been errors made in writing on the disk that result in parts of
various files being combined without the user's knowledge.
Example: On most magnetic disks, there is a file
allocation table with entries pointing to where on the
disk each file is stored. Compromise of data can occur
if there is a cross-link; that is, if an entry in the
file allocation table for one file actually points to
part of another file. As files are accessed and
modified, it is often not possible to write the entire
file in a contiguous set of storage locations.
Therefore, the file becomes fragmented. The more a disk
is used, the more fragmented the files become, and the
greater the probability of a cross-link. In order to
guard against compromise of information due to a cross-
link, all information on the disk is considered to have
the same sensitivity.
It is also likely that classified or sensitive, but unclassified,
information that has been "deleted" from the system is still resident
on the media, unless it has been completely written over in an
approved manner. (See Reference 4 for guidance on overwriting media.)
Therefore, the media and all information on the media should be
regarded as having a single sensitivity level.
It is certainly permissible to have some information on a volume of
magnetic media that is actually less sensitive than the sensitivity
level of the volume; however, due to the fact that it is impossible
for the average user of an OA System to tell exactly what is written
where, security dictates that this information be treated as having
the higher sensitivity level.
Example: Suppose that a floppy disk is marked
"Personnel privileged information," and there is a file
on this disk that contains only unsensitive information,
such as the General Schedule salary tables. While this
unsensitive file is on the sensitive disk, it must be
treated as sensitive, because bad pointers or other
problems could cause the file to actually contain
sensitive information. Further, this file CANNOT be
copied to another floppy disk unless the second floppy
disk is also considered to be sensitive, due to the
possibility of "Personnel privileged information"
unintentionally being copied.
If there is a file that is believed to be unsensitive that is stored on a
sensitive disk, it is permissible to have a copy of that file printed,
manually reviewed, and determined to be unsensitive. This paper copy can
then be treated as unsensitive; however, the disk itself should still be
considered to be sensitive. This applies to classified information as
much as it does to sensitive, but unclassified, information.
2.3 OA Systems With Fixed Media vs. OA Systems With Removable Media
"Removable media" are any magnetic storage media that are meant to be
frequently and easily removed from the OA System by a user. Examples of
removable media include floppy disks, cassette tapes, and removable hard
disks.
"Fixed media" are any magnetic storage media that are not meant to be
removed from the system by a user. Examples of fixed media include fixed
disks and nonvolatile memory expansion boards.
An OA System with removable-media-only is one which meets both of the
following criteria: (1) the system does not currently use fixed media
(e.g., Winchester disks) to store or process information; and (2) other
than removable media such as floppy disks or cassette tapes, the OA System
must have only volatile memory. (In determining whether or not the OA
System contains fixed media, any read-only memory (ROM) the system
contains can be ignored.) If either condition is not met, the system
should be regarded as containing fixed media.
The sensitivity level of an OA System with removable-media-only can be
easily changed, because all classified and sensitive, but unclassified,
information can be removed from the system after each use. This is not
true of an OA System with fixed media--the sensitivity level of the system
cannot be lowered without a great deal of effort, because it is virtually
impossible to remove all classified and sensitive, but unclassified,
information from the system. Therefore, if it is desired that the OA
System be used to process information of several different sensitivity
levels, or that it be used by personnel with different levels of
clearances, an OA System with removable-media-only should be used. (See
Sections 4.1.2.2 and 4.2.2.2 of this guideline for guidance on changing
the sensitivity levels of OA Systems.)
PART II:
GUIDANCE FOR THE OFFICE AUTOMATION SYSTEM USER
3.0 RESPONSIBILITIES OF OA SYSTEM USERS
One of the most common problems in Information Security is determining
exactly who is responsible for what. This is a particularly important
issue when Office Automation Systems are involved, since there is much
less opportunity for oversight of "average users" by "professional
security people." Therefore, it is incumbent upon each person to do his
or her part to prevent the compromise of information.
The "average user" of an Office Automation System is the most important
person in maintaining OA System security. If security is to be
maintained, the user must develop a "security mindset"[16]. In view of
this, the following general responsibilities of all OA System users are
described. It should be remembered that responsibilities discussed in
this section apply equally to each user of an OA System, regardless of
whether or not that person has been formally designated as the security
officer for that OA System.
(1) Each user of an OA System should know who the security officer for
that system is, and how to contact that person.
(2) Each user of an OA System should have an awareness of the applicable
security guidelines[5,11,16,23]. Users should follow the applicable
guidelines. If it is necessary in an emergency to deviate from the
security guidelines, the user should report this deviation to a security
officer as soon as possible, so that the security officer can take
appropriate action.
(3) In addition to violations of security procedures, each user should
report suspected or known compromise of information and/or theft of
property to a security officer[5,23]. If a user believes that a part of
the OA System (including software and magnetic media) is missing or
damaged, or has been changed, and the user is unable to determine why and
by whom the change was made, then the problem should be reported to the
ADPSSO at once. Similarly, if a user has reason to believe that
information may have been copied, modified, or destroyed improperly, the
security officer should immediately be notified.
(4) It is the responsibility of each user not to use software provided by
an unauthorized source. The user should not violate any copyrights or
other license agreements, and is responsible for reporting any known
violations to the security officer. Further, the user should not use any
software which he has obtained without ensuring that it has first been
thoroughly tested in an environment in which no operational information
can be compromised or damaged.
4.0 OPERATIONAL SECURITY FOR STAND-ALONE OFFICE AUTOMATION SYSTEMS
4.1 O A Systems With Removable-Media-Only
4.1.1 Physical Access to Systems and Media
Physical access to the OA System at any given time should be limited to
those with clearance and need-to-know for all information then contained
in the system. It may be necessary to keep the OA System in a separate
room or part of a room to keep unauthorized personnel from being able to
read information displayed on the screen or on a printer. If the OA
System is not in a protected area, special care should be taken to ensure
that unauthorized personnel cannot gain access to sensitive, but
unclassified, or classified information.
Example: Kelly, who is in charge of office personnel
affairs, must process the quarterly promotion list,
which contains personnel information that must be
protected under the Privacy Act of 1974[20]. The OA
System on which he must work, however, is located in the
middle of the office, where several people who are not
authorized to see the information can see what he is
doing. Kelly should therefore take care to ensure that
none of his co-workers can see the information he is
processing. One way he might do this is to use
partitions to surround the OA System and block the view
of other employees. A second way is to position the CRT
screen and printer in such a way that no one else in the
office can see them, and then to ensure that no one is
watching what he is doing. A third way is to make sure
that the room is empty before doing his work.
It is important to emphasize that these rules also apply for personnel
performing maintenance on the OA System. Maintenance, regardless of
whether preventive or corrective, should only be done by authorized
persons. Maintenance personnel should not be allowed physical access
to the OA System until all classified and sensitive, but unclassified,
information for which they do not have a clearance and need-to-know
has been removed.
4.1.2 Using the Stand-Alone OA System With Removable Media
Only
4.1.2.1 Normal Operation
The following procedures should be followed at all times during normal
operation of the OA System:
(1) Monitor screens, printers, and other devices that
produce human-readable output should be placed away from
doors and windows. This helps ensure that casual
passersby cannot read information from
them[5,8,11,19,23].
(2) Never leave an OA System running unattended while it
contains information that should not be seen by everyone
with physical access to it. Especially, do not leave an
OA System unattended while classified or sensitive, but
unclassified, information is displayed on the screen.
If a user must leave an OA System, he/she should follow
the procedures outlined in Section 4.1.2.4 of this
Guideline.
Example: Suppose that Tom edits a large data file
containing personnel records on an OA System. When
he is finished, he saves the edited file. Since
writing the new file over the old one will take
some time, Tom leaves the OA System to run an
errand. Sue sees that the OA System is
unattended, and accesses and modifies the
personnel file, destroying its integrity.
(3) Electronic labels attached by the OA System to
information on magnetic storage media should not be
trusted to be accurate unless the OA System has been
evaluated by the National Computer Security Center and
has been found to be a B1 or higher trusted system.
While it is a good practice to indicate the apparent
sensitivity of information by an electronic label of
some sort (e.g., by a character string in the file name
or directory name, or by the value of the first byte in
the file), these labels should not be trusted to be
accurate. Therefore, all data on the media should be
treated as being at a single sensitivity level--that
which is indicated by the physical label attached to the
media.
(4) It is not normally permissible to have a classified
or sensitive, but unclassified, volume of magnetic
storage media on line at the same time as a volume with
a lower sensitivity level, unless the sensitivity level
of the latter volume is immediately raised. (The
exception to this is discussed Section 4.1.2.3.)
Example: Suppose that Terry has a file that she
believes to contain only Unclassified information,
but that is stored on a TOP SECRET floppy disk.
Terry therefore copies the file to an Unclassified
disk. The previously Unclassified disk should then
become TOP SECRET. The reason for this is that
there is no way for a user to determine exactly
what has been written onto the disk; there is a
chance that an error caused TOP SECRET information
to be written onto the disk.
(5) Printers should not be left unattended while
classified or sensitive, but unclassified, information
is being printed unless the area in which it is located
provides a level of physical security adequate to
protect the printout from being read, copied, or stolen
by an unauthorized individual.
(6) Any user who prints out classified or sensitive,
but unclassified, information should remove that
printout from the printer and/or printer area at the
earliest possible time. If this is not done, classified
or sensitive, but unclassified, information could be
compromised by an unauthorized person reading, copying,
or stealing a printout. (Note: this is particularly
true if the printer is shared, and/or is not collocated
with the rest of the OA System. Even if adequate
physical security can be provided, it is good practice
to remove the printout from the printer area at the
earliest possible time.)
Example: Suppose that Pat is John's supervisor,
and prints out John's personnel records on a
printer. Pat then leaves the printout next to the
printer, and leaves the room to attend a meeting.
While Pat is gone, John's co-worker George walks
into the room, notices the printout, and reads
John's personnel records. This is a compromise of
information, and is a violation of the Privacy Act
of 1974[20].
(7) The user should ensure that all printouts have
appropriate sensitivity markings (e.g., "Personnel
Privileged Information," "Proprietary," "Confidential,"
etc.) at the top and bottom.
(8) If the printer ribbon is used to print classified
information, it should be marked at the highest
classification level it was used for, removed from the
printer when not in use and stored and otherwise
protected and disposed of as any other classified item.
(9) Use only software that has been obtained from
authorized sources. Do not pirate software yourself,
and do not use any software which has been obtained by
violation of a copyright or license agreement.
Furthermore, software should not be used unless it has
been thoroughly tested by someone trustworthy (such as
the organizational software distribution office, or the
ADPSSO) for errors and malicious logic before it is
exposed to operational information. (This is especially
true for software obtained from the public domain.)
(10) Do not eat, drink, or smoke while using the OA
System. Any spillage could seriously damage the system
and/or magnetic media.
(11) Protect magnetic media from exposure to smoke,
dust, magnetic fields, and liquids. Diskettes that get
wet will generally warp or become otherwise deformed.
If a diskette or other volume of media does get wet, do
not attempt to use it in an OA System, as doing so could
result in damage to the system.
(12) If a manual audit log is kept for the system,
record in it all necessary information.
(13) No information should be processed or stored on
any OA System until a risk analysis has been completed
and appropriate countermeasures have been determined.
(14) No classified information should be processed or
stored on any OA System unless that system has been
TEMPEST-approved for the zone in which it is
operating[14,15].
4.1.2.2 Changing the Sensitivity Level of Information the OA
System is Processing
OA Systems using removable-media-only contain no fixed media, and
therefore can be used to process information of different sensitivity
levels. In some instances it may be more cost effective to simply
process all information as being at the system high level, and then
manually review all output for the proper sensitivity. However, if
this is impractical, then the sensitivity level of the OA System may
be changed. When a change in the sensitivity level is desired, the
following steps should be taken:
(1) Remove all storage media from the system (this
includes media containing both applications and systems
programs).
(2) Power off the system, preferably for at least one
minute. (This will allow any latent capacitance to
bleed off, and ensure that memory is cleared. Again,
the exact time required depends on the particular system
used, and the system security officer should specify an
appropriate minimum time for systems under his/her
control.)
(3) Power on and reboot the system with the copy of the
operating system that is at the proper sensitivity
level.
(4) Insert the applications media for the new
sensitivity level into the system. There should be a
different copy of the operating system, and of each
applications package (e.g., a word processing package)
for each classification of information the system
processes (e.g., an Unclassified copy, a SECRET copy).
It is recommended that there also be a different copy of
the operating system for each sensitivity level of
information the OA System processes (e.g., a "Personnel
Privileged" copy, a "Company X Proprietary" copy). Each
copy should be protected to a level appropriate for the
sensitivity of information it is used to process.
There is one exception to this guidance. To use only
one copy of an operating system or applications package
for all sensitivity levels, the procedure is: first,
boot the system or load the package with no classified
or sensitive, but unclassified, information in the
system. Then, remove the diskette or tape containing
the software BEFORE any classified or sensitive, but
unclassified, information is introduced into the system.
DO NOT reinsert the software into the system until the
sensitivity level of the system has been changed using
the procedures described in Section 4.1.2.2
(5) The ribbon used to print classified or sensitive,
but unclassified, information should be replaced by one
used to print information of the new sensitivity level.
The sensitive (or classified) ribbon should be either
securely stored or disposed of, as appropriate.
4.1.2.3 Preparing Downgraded Extracts
In some instances, it may be necessary to copy some information from a
volume of media at one sensitivity level to another volume that is at
a lower sensitivity level (e.g., copy a file from a SECRET disk to an
Unclassified disk). This is an extremely dangerous practice, and
should only be done following the procedures that have been set by the
security officer. Users should contact their system's security
officer for specific guidance on preparing downgraded extracts of
classified or sensitive, but unclassified, information.
4.1.2.4 When a User is Finished Using the OA System
When a user is through using the OA System, remove all removable media
from the system and store it in a manner commensurate with information
of that sensitivity. Record any audit trail information that may be
required. If the system is used by more than one person at different
times, it is advisable to power the system off at the conclusion of
each person's use.
4.1.2.5 At the End of the Shift
At the end of the shift or workday, the following steps should be
taken before leaving.
(1) Remove all removable media from the OA System.
(2) Overwrite each location in the system's memory with
some pattern (e.g., all zeros, then all ones, then a
random pattern) before the system is powered off.
(3) Power off the system. If there is a key, it should
be stored in a secure place until the next shift or
working day.
(4) Any printer ribbon that has been used to print
classified or sensitive but unclassified, information
should be removed, and either securely stored or
properly disposed of.
The OA System should remain powered off during non-duty hours.
A checklist should be maintained that is signed or initialed at the
end of each day to verify that the OA System has been properly shut
down and removable media have been removed. This will assist in
determining accountability for a discovered security problem.
4.2 OA Systems With Fixed Media
4.2.1 Physical Access to Systems and Media
Physical access to the system should be restricted to those who are
authorized access for all data currently being stored on the system.
In addition, these users should be authorized access for all data that
has been stored on the system since the system was last declassified.
(See Reference 4 for declassification procedures.)
4.2.2 Using the Stand-Alone OA System with Fixed Media
4.2.2.1 Normal Operation
During normal operation of a stand-alone OA System with fixed media,
all recommendations given in Section 4.1.2.1 which apply to the
operation of an OA System with removable media are still applicable.
However, additional vulnerabilities exist with OA Systems containing
fixed media and therefore additional precautions must be taken.
Even though only one user can directly access the system at a time, it
is likely that information originated by more than one user will be
stored on the fixed media. Access to any classified information by a
user not possessing a clearance or need-to-know for it is a violation
of Executive Order 12356[6]. Access to certain other types of
sensitive, but unclassified, information is contrary to the provisions
of Section 3 of the Privacy Act of 1974[20]. Systems which do not
meet the requirements of at least class C2 cannot provide assurance of
protection of information from anyone who gains physical access to the
system. Therefore, if the OA System has been evaluated and found to
be a class C2 or higher system, then the guidelines detailed in
Reference 3 apply. Otherwise, all users should have proper clearance
and need-to-know for all data that is stored or processed on the
system.
Any removable media which is placed in the OA System automatically
acquires the same sensitivity level as the system. However, if the
original sensitivity level of the removable media is more restrictive
than that of the OA System, the OA System and its fixed media acquire
the more restrictive sensitivity level, and should be marked as such.
Example: Suppose that there is an OA System with one
fixed disk and one floppy disk drive. The system and its
fixed disk are classified SECRET. A previously Unclass-
ified floppy disk placed in the system's floppy disk
drive becomes classified SECRET. If a TOP SECRET floppy
disk is placed in the floppy disk drive, however, the
entire OA System and its fixed disk become classified TOP
SECRET.
It should not normally be permissible to copy a file from a classified
or sensitive, but unclassified, volume of removable storage media to a
volume of fixed media with a lower sensitivity level, unless the
sensitivity level of fixed media, and of the entire OA System, is
immediately raised to the level of the removable media. (The
exception to this is discussed in Section 4.2.2.3.)
Example: Suppose that there is a file that is apparently
Unclassified, yet it currently resides on a TOP SECRET
diskette. If this file is copied to an Unclassified fixed
disk, the sensitivity level of the previously Unclassified
disk should now be TOP SECRET. The reason for this
requirement is that we have no way of being sure exactly
what is being copied; therefore, we must assume the worst
case: that some TOP SECRET information may be
inadvertently copied onto the Winchester disk. Therefore,
the sensitivity level of this previously Unclassified disk
should be raised.
Furthermore, it should not be permissible to copy a file from a
classified or sensitive, but unclassified, volume of fixed media to a
volume of removable media with a lower sensitivity. If this does
occur, the sensitivity of the removable media should be immediately
raised.
Information that individual users wish to protect from other users of
the OA System should be stored on removable media. This removable
media can then be appropriately protected when it is not in use. This
recommendation stems from the fact that OA Systems that do not meet
the TCSEC requirements for at least class C1 cannot prevent any system
user from gaining access to any location in the system's memory, to
include the locations where the hardware/software controls themselves
are stored. If the information is removed from the system along with
the media it resides on, however, it cannot be accessed by others.
(However, users should be very careful, as quite often information is
left on the fixed media in the form of scratch files or backup files.)
Users should make sure that media they remove from the OA System are
properly secured. For example, if a floppy disk is removed, it should
be locked away, not left lying on top of a desk or put in an unlocked
container. One of the conditions for security is that adequate
physical protection must be provided; if it is not, then all
information is vulnerable.
4.2.2.2 Changing the Sensitivity Level of Information the OA
System Is Processing
It is not permissible to lower the sensitivity level of the OA System
unless it has been declassified using the procedures described in
Reference 4.
Unless the OA System meets the requirements of at least class B1 when
evaluated against the TCSEC, it should not be used to process multiple
sensitivity levels of information simultaneously. In this case, it is
not permissible to change the sensitivity level of the information the
OA System is processing. Any information which is being processed by
the OA System must be regarded as having the same sensitivity level as
the system itself, regardless of its apparent sensitivity.
4.2.2.3 Preparing Downgraded Extracts
In some instances, it may be necessary to copy some information from a
volume of media at one sensitivity level to another volume that is at
a lower sensitivity level (e.g., copy a file from a SECRET disk to an
Unclassified disk). This should only be done following the procedures
that have been set by the security officer. Users should contact
their ADPSSO for specific guidance on preparing downgraded extracts of
classified or sensitive, but unclassified, information.
4.2.2.4 When a User is Finished Using the OA System
If there are any classified or sensitive, but unclassified, files
stored on the fixed media that other users of the system should not be
able to access, they should be removed from the system[8,9]. First,
copy the files to a volume of removable media. Then, remove the
information contained in these files from the fixed media by
overwriting each location that contained these files with some pattern
(e.g., all zeros, then all ones, then a random pattern)[8,9]. The
software that is used to do the overwrite should be trusted to a level
commensurate with the OA system level of sensitivity.
4.2.2.5 At the End of the Shift
See Section 4.1.2.4. All safeguards described there are equally
applicable to OA Systems with fixed media.
In addition, the OA system itself should be physically secured in some
way. If the room containing the OA system is approved for open
storage of classified information at the highest level of information
contained on the OA System, it may be sufficient to secure the room in
the appropriate manner. If the room is not approved for open storage
of classified information, then the OA System itself should be secured
by locking it in an approved cabinet. 5.0 OPERATIONAL SECURITY FOR CONNECTED OFFICE AUTOMATION SYSTEMS
(Note: In addition to the guidance given in this section, all
guidance given in Chapter 4 of this guideline is also applicable, and
should be followed whenever the OA System is used.)
5.1 Using an OA System as a Terminal Connected to Another Automated
Information System
When an OA System is used as a terminal, all of the normal rules for
connecting terminals to AIS should apply[10]. For example, these
rules should include never leaving the OA System unattended while it
is connected to another AIS, unless a software locking mechanism is
used which prevents anyone, not passing an authentication check, from
interacting with the remote AIS.
5.1.1 Office Automation Systems Versus "Dumb Terminals"
Office Automation Systems used as terminals can cause security
problems that do not occur when "dumb terminals" (i.e., those that are
not programmable) are used. Among these are the possibility of
malicious communications software in the OA System, and the ability of
the OA System to store such things as passwords.
Users of OA Systems should be wary of untested communications
software. The organization owning the OA System should take any steps
practicable to ensure that communications software used with their
systems does exactly what its documentation claims, and nothing else.
In general, at least one copy of the software should be tested, either
by someone within the organization or by someone outside of the
organization who can adequately test software.
If communications software is used that contains malicious code, the
communications software can cause information (including the user's
password) to be compromised, can corrupt information flowing between
the OA System and other AIS, or can cause service to be denied
completely. Worse still, it can do much of this without the knowledge
of the person using the software. Therefore, it is very important not
to use communications software packages that have not been approved
for use by a responsible security officer.
Under no circumstances should a user's password for any remote AIS
ever be stored in an OA System[11]. While it may seem convenient to
program the OA System to execute the login routine on a mainframe
computer system for you, it is important to remember that the OA
System can also execute the same routine for someone else. This can
result in another user of the OA System being logged into a remote AIS
as you!
Example: Suppose that Janet programs her personal computer
so that when she is communicating with the AIS called
MAINFRAME and presses the CONTROL and BREAK keys at the same
time, her PC sends out her user-identifier and password to
MAINFRAME. In other words, the PC executes Janet's login
routine on MAINFRAME for her. She thus saves the keystrokes
involved in typing the information each time she logs in,
and doesn't even have to remember her password!
The problem occurs when Pat sees what Janet does, and
decides to take advantage of this "user-friendliness." When
Joe is not around, Pat simply connects Janet's PC to
MAINFRAME, presses the CONTROL and BREAK keys
simultaneously, and is now logged onto MAINFRAME as Janet.
Once this happens, there is no way to prevent the compromise
of information, since MAINFRAME has no way of knowing that
it is not really Janet at the other end of the terminal!
In summary, storing a password in an OA System is the same as writing
it down on a piece of paper--if anyone ever finds it, the security
that was to be provided by that password has been defeated.
5.1.2 Consequences of Removable Media vs. Fixed Media
Because the sensitivity level of an OA System with fixed media cannot
be easily changed, it is difficult to use one of these systems as a
terminal to a wide variety of other AIS, particularly if each of these
remote AIS is processing information of different sensitivity levels.
Therefore, once an OA System with fixed media is connected to an AIS
processing classified information, that OA System should be considered
to be classified. It should NOT be connected at a later time as a
terminal to an AIS that is not approved to process information
classified at the same or a higher level.
An AIS with removable-media-only, however, can more easily be used as
a terminal to, for example, a SECRET host at 2:00 pm and an
Unclassified host at 4:30 pm, because its sensitivity level can be
changed. If you are using an OA System with removable-media-only, and
it is necessary to connect to an AIS that is processing a different
sensitivity level of information than the last AIS that the OA System
was connected to, the sensitivity level of your OA System should be
changed in accordance with Section 4.1.2.2 of this guideline.
5.2 OA Systems Used as Hosts on Local Area Networks
Suppose that there is an OA System attached to a Local Area Network
(LAN). It is important for both the user and the security officer to
understand that, as a general rule, any person who can access any
other component of that LAN can access any information contained in
that OA System. This includes any information that is stored on both
fixed and removable media that are currently contained in the system,
and applies regardless of whether the person is accessing the OA
System from its keyboard or over a network. Therefore, the problem of
compromise of information to an unauthorized individual is greatly
increased any time an OA System is connected to a network. For this
reason, the user should NEVER leave the OA System while it is logged
in to the LAN.
5.2.1 Consequences of Removable Media vs. Fixed Media
If some information in the OA System is stored on removable media,
those media can be removed from the system so that the information
cannot be accessed by a remote user. If the information is stored on
fixed media, it cannot be easily removed from the system, and the
owner of the information should be aware of its vulnerability to
compromise.
Suppose that there is an OA System that does not meet the class B1
requirements and that is used as a LAN host. Any information that
should not be shared with every user of the LAN should be stored on
removable media, and these media kept out of the OA System when this
information is not needed.
If the OA System meets the requirements of class B1 or higher, then
these media may be left in the system.
5.2.2 Controlling Access to System Resources
In order to prevent the compromise of information, access to the
resources of the LAN and of each OA System connected to it should be
controlled. These controls may include physical, procedural, and
hardware/software features, or some combination thereof.
One way to ensure that information is not compromised is to provide
such hardware/software features as access control, identification and
authentication, and audit. If these features are provided, and the
network as a whole can be trusted to prevent users from gaining access
to information for which they are not authorized, then the other
controls needed for security (e.g., procedural controls, physical
access controls) are similar to those required for stand-alone OA
Systems.
However, since the hardware/software controls necessary to provide
security in a LAN are often unavailable, procedural controls should be
implemented. These include:
(1) Have all OA Systems connected to the LAN operate at the same
sensitivity level. That is, there should be no information
processed anywhere on the LAN that some user of the LAN does not
have a clearance, formal access approval, and need-to-know.
Users should make certain that they remove from their OA Systems
any media containing information that they do not want to share
with each other user of the LAN.
(2) Provide specific LAN-oriented physical access controls.
Instead of keeping unauthorized personnel away from a single OA
System, it is now necessary to keep them away from all OA Systems
that are connected to the LAN. Some of these OA Systems may be
located or may have peripheral devices (e.g., shared laser
printers) that are located in public areas. Therefore, each user
must help to ensure that no one is using any part of the LAN
without authorization. Further, each user should pick up any
human-readable output from any shared devices as soon as
possible. For example, printouts should not be left in the
printer room for six or eight hours if the room is not
sufficiently protected to keep unauthorized personnel from
gaining access to classified or sensitive, but unclassified,
information. A good rule of thumb is, if you don't want others
to read a sensitive file, do not leave it where it can be seen.
PART III:
GUIDANCE FOR ADP SYSTEM SECURITY OFFICERS
6.0 RESPONSIBILITIES OF THE ADPSSO
There should be one individual who is responsible for the security of
each Office Automation System[5,11]. This individual may be one of
the users of the system itself, or he/she may be a person who has
responsibility for the security of all OA Systems within the
organization. (It should not be the OA System manager, due to the
potential lack of accountability.) Regardless of who the individual
is, the ADPSSO has certain responsibilities which must be carried out
in order to ensure that the OA security policy is enforced. These
include:
(1) Ensuring that each OA System is certified and accredited, if
required by organization policy.
(2) Ensuring that all users of the system are aware of the security
requirements, and assuring that all procedures are being followed.
(3) Investigating all reported or suspected security violations, and
determining (to the best of his/her ability) what has happened.
(4) Reporting violations to appropriate authorities (e.g., top
management, agency security officers, etc.).
(5) Ensuring that the configuration management program is followed.
He/she should approve maintenance before it is done, and ensure that
no changes are made to either the hardware or software of the system
without approval.
(6) Reviewing the audit logs for anomalies (if audit logs are used).
(7) Enforcing (and possibly also developing) procedures by which
downgrading of information contained on magnetic media can be done, if
the organization permits such downgrading. 7.0 THREATS, VULNERABILITIES AND CONTROLS
7.1 Threats, Vulnerabilities, and Controls: an Overview
The security officer of any OA System should have a familiarity with
some of the security issues involved with that system. This chapter
will give the security officer that familiarity.
In computer security terminology, a threat is a person, thing, or
event that can exploit a vulnerability of the system. Examples of
threats include a maintenance man who wants information to sell, a
wiretapper, or a business competitor.
A vulnerability is an area in which an attack, if made, is likely to
be successful. Examples of vulnerabilities include lack of
identification and authentication schemes, lack of physical access
controls, and lack of communications security controls.
If a threat and a vulnerability coincide, then a penetrator can cause
a violation of the system's security policy. For example, suppose
that there is a maintenance person (the threat) who is secretly
working for an unscrupulous contractor. In addition, there is a
vulnerability in that lack of physical access controls allows
maintenance personnel to work on the OA System without supervision.
In this case, information may be corrupted, causing a disruption in
the normal work routine.
A security control is a step that is taken in an attempt to reduce the
probability of exploitation of a vulnerability. This control may take
one of many forms: an operational procedure, a hardware/software
security feature, the use of encryption, or several others.
There are many possible threats to the information being stored by an
Office Automation System, as well as to the system itself. The system
may be stolen or destroyed. Information stored on the system may be
compromised; that is, it may be exposed to a user or process that does
not have proper authorization to see it. Information may also be
corrupted or destroyed altogether by a malicious user. Another threat
might be the interference with the system's ability to process
information correctly. It is the purpose of this document to educate
the security officer and the user as to the proper defenses against
each of these threats. The following is a breakdown of some of the
security issues involved in combating each of several types of
threats.
7.2 Physical and Personnel Security
7.2.1 Physical and Personnel Security Threats and
Vulnerabilities
In many instances, there is a danger that classified or other
sensitive, but unclassified, data being processed in an OA System will
be exposed to someone without a proper clearance or authorization for
it. This is particularly true if the OA System is not physically
located in an appropriate area, or if an OA System is directly
accessible to external users by a communications line.
(An "appropriate area" is one that is approved for the highest level
of information that has ever been processed or stored on the OA
System.)
For the purposes of determining the level of security needed for an OA
System, the following rule should be used:
Any information that can be accessed using the
communications capability of an OA System should be
regarded as being processed by that OA System.
This may mean that a more stringently controlled area is needed for a
particular OA System, or that certain communications should not be
allowed.
Example: Suppose that there is an OA System
physically located in an area that is approved for
no higher than SECRET information. If the OA
System is connected to another AIS that contains
TOP SECRET information, and the remote AIS is not
trusted to separate TOP SECRET and SECRET
information, then the OA System should be regarded
as processing TOP SECRET information. In this
case, there are two things that can be done: not
allow the connection of the OA System to the remote
AIS, or upgrade the physical surroundings of the OA
System so that TOP SECRET information may be stored
there, and institute physical and procedural
controls to ensure that only personnel with TOP
SECRET clearances can gain physical access to the
OA System.
Regardless of the physical area in which the OA System is located, it
is possible that all or part of the machine can be stolen or modified.
The theft of a hardware part of the system may result in damage being
done to the owning organization, since many times it is possible to
recover residual information directly from the hardware.
7.2.2 Physical Access Controls
The OA System should be located in an area that is approved for data
as sensitive as the highest level of information it has stored or
processed since all of its fixed media and semiconductor media were
last declassified. Further, any other AIS or AIS component that can
access the OA System should also be located in an area that is
approved for this highest sensitivity of information.
Example: Suppose that an OA System is used to process
TOP SECRET data. This system should be stored in an
area that is approved to store at least TOP SECRET
material. (This requirement holds even if some or most
of the information processed on the system is classified
at a lower level than TOP SECRET.) Any other AIS or AIS
component that is logically connected to this OA System
must also be kept in an area that is approved for TOP
SECRET data.
Regardless of the physical area in which it is located, the OA System
should be marked with the most restrictive sensitivity of information
that may be processed on it. (See the Appendix of this Guideline for
detailed guidance on the marking of OA Systems.)
The OA System itself should be protected in such a way that sufficient
protection is provided against theft or destruction of the system or
its components. Possible precautions that can be taken include
locking the OA System and its peripheral devices to a table, locking
it in a cabinet, or keeping it in a locked room or vault. Any
apparent theft or destruction of the OA System or any of its
components (to include software) should be reported immediately to the
security officer.
7.2.3 Personnel Security Controls
Executive Order 12356 states that "A person is eligible for access to
classified information provided that a determination of
trustworthiness has been made by agency heads or designated officials
and provided that such access is essential to the accomplishment of
lawful and authorized Government purposes"[6]. The Privacy Act of
1974 states that no agency may disclose privacy information to any
person without the prior written consent of the person to whom the
information pertains, except for a limited set of purposes[20]. In
order to meet these and other policy-based requirements, only
personnel who possess the proper clearances, formal access approvals,
and need-to-know for all information then contained in the OA system
should be allowed physical access to the system. Under ideal
circumstances, maintenance or configuration changes that must be done
by vendor or support personnel should only be done by personnel who
are cleared for and have a need-to-know for all information then
contained in the system. If this is not possible, then vendor or
support personnel should be escorted by someone who is cleared and has
a need-to-know for all information on the system. If the OA system or
parts of it must be sent to another location for repair, care should
be taken to ensure that no one without the proper clearances and need-
to-know for information previously contained (or possibly contained)
in the system at any given time has access to the OA System at that
time.
7.3 Communications Security
7.3.1 Communications Security Threats and
Vulnerabilities
Communications Security vulnerabilities are those that can be
exploited whenever an Office Automation system has the capability to
electronically send information to or receive information from another
AIS. These vulnerabilities exist primarily in two areas: (a)
interception of information during transmission, and (b) non-detection
of improper messages and message headers received by the OA System.
Whenever an OA System is used to electronically send information to or
receive information from another computer system, there is a chance
that the information will be compromised by being intercepted while en
route. Therefore, steps should be taken to ensure that no information
is compromised during transmittal.
In addition to the problem of compromise, an OA System receiving
information from another system should have some amount of assurance
that the message and its header are authentic--that is, the receiving
OA System is not being tricked into believing a false header. The
integrity of messages and control information is crucial to the secure
operation of a network. If a message were to be received with a phony
header that was not detected, it could cause the system or a human
using that system to take some action that would violate the security
policy. Therefore, any forged messages or message playback should be
detected by the OA System or by the network it is connected to.
For additional information, please contact your organization's
Computer Security Office. Additional information is available from
NSA, 9800 Savage Road, Ft. George G. Meade, MD 20755-6000, Attention:
DDI.
7.3.2 Communications Security Controls
Regardless of whether the system is being used as a terminal attached
to a mainframe or as a host attached to a local area network, either
encryption or physically protected communications media should be used
whenever the OA System is used for the communication of classified
information. This protection must be sufficient for the highest
classification of data that will be transmitted over the
communications media.
Encryption should be used to protect information from being
compromised any time it is not possible to physically protect the
communications media. In addition, cryptographic techniques may be
considered even when communications media can be physically protected
to the desired level. This is because the use of encryption will not
only help prevent compromise of information by interception, it will
also help prevent spoofing. Cryptographic checksums can be used to
verify the integrity of the message and its sender.
The term "physically protected communications media" means that the
media (e.g., the communications lines) cannot be accessed by a system
penetrator (that is, they are immune to a hostile wiretap, either
active or passive), and that TEMPEST considerations do not raise a
significant problem in the specific environment. An example of
physically protected communications lines is communication cables that
are physically located within a secure area and are used to connect OA
Systems in a LAN.
7.4 Emanations Security
Under certain circumstances, it is possible to detect what information
is being processed by a computer system by analyzing the
electromagnetic emanations coming from the system. This could result
in the compromise of classified or sensitive, but unclassified,
information. To prevent this, OA Systems that process classified
information must be protected in accordance with the National Policy
on the Control of Compromising Emanations. For specific applications
see NACSI 5004, "TEMPEST Countermeasures for Facilities Within the
United States (U)"[14], and NACSI 5005, "TEMPEST Countermeasures for
Facilities Outside the United States (U)"[15]. (Note: The entire OA
System must be protected. Connecting a TEMPEST approved CPU, monitor,
printer, and keyboard together with an unapproved cable or without due
regard for proper RED/BLACK separation and installation criteria can
result in the failure of the entire system to meet the TEMPEST
requirements.)
7.5 Hardware/Software Security
7.5.1 Hardware/Software Threats and Vulnerabilities
Hardware/Software vulnerabilities are those that can be
exploited because of the inability of the OA System's hardware,
software, and firmware to prevent users from accessing data in
or controlled by the system.
The threats to exploit these vulnerabilities generally fall into one
of three general categories: compromise of classified or sensitive,
but unclassified, data; unauthorized modification or destruction of
data; and denial of services to authorized users. More specifically,
an unauthorized user can access data, can modify data, or can deny use
of the data or even the OA System itself to authorized users.
If an OA System is networked, the vulnerability of data is greatly
increased. First, a user of one OA System may be able to access
another AIS, and data that was previously inaccessible is vulnerable
to attack. Second, an unauthorized user may be able to access the OA
System from a remote location, and thus evade the physical and
procedural controls that have been set up to protect the OA System
locally.
7.5.2 Hardware/Software Controls
Most current OA System architectures do not provide the hardware
features which are needed to implement separate address spaces (or
"domains") for the operating system and applications programs. They
also do not provide the privileged instructions that are necessary to
prevent applications programs from directly performing security-
relevant operations, nor do they provide memory protection features to
prevent unauthorized access to sensitive parts of the
system[16,21,23].
The limitations of these single-state OA Systems prevent them from
providing effective hardware/software security features. For example,
a knowledgeable user can access any memory location directly by using
assembly language-type commands. (The memory locations which he/she
can access in this manner include not only the system's own
semiconductor memory, but also everything currently accessible to any
part of the system, such as floppy disks, fixed disks, and cassette
tapes.) In this manner, a user can read, modify, and/or destroy any
information contained in the OA System--including security critical
entities such as password files and encryption information. The
system cannot protect itself from an unauthorized user.
There are currently a number of hardware and software packages
available on the market that claim to provide security for data
resident on the system. On all current OA Systems that support only a
single processor state, it is easy to circumvent these packages. For
example, a user may be able to bypass a security package by booting
the system with a different copy of the operating system--one that
does not have the security features on it[16,21]. A user may
additionally be able to use one of the commercially-available
utilities packages to bypass security controls[16,21].
Despite their weaknesses, some current hardware/software packages do
have uses. Packages which provide such mechanisms as user
identification and authentication, discretionary access controls, and
audit trails can provide a degree of protection that is certainly
better than that provided by an OA System without them. In addition,
hardware/software controls can help to prevent accidents. If these
controls are used, it is much less likely that a non-malicious user of
the OA System will accidentally gain access to, modify, or delete
information belonging to other users. A user will have to make a
determined effort to gain access to information belonging to other
users.
There are currently some microprocessors available that provide the
hardware features necessary to support hardware/software security
controls (e.g., multiple processor states). OA Systems that are based
on these microprocessors and that have the necessary security
mechanisms can be evaluated against the TCSEC[2]. With the proper
hardware/software security features added on, it is possible for the
OA System to reach the class B1 level, when evaluated against the
TCSEC. In addition, if OA Systems are designed with hardware/software
security as an initial consideration, they would be able to achieve
any trust level defined by the TCSEC.
In summary, hardware/software controls should not be relied upon by
themselves to provide separation of users from information in most
current OA Systems. However, as long as these controls do not lull
the user into a false sense of security, they will not harm and may
assist in raising the overall level of Office Automation security.
7.6 Magnetic Media
7.6.1 Magnetic Remanence: Threats, Vulnerabilities,
and Controls
Magnetic remanence is the residue remaining on magnetic storage media
after a file has been overwritten or the media have been degaussed.
Many times, after a file has been overwritten or media have been
degaussed, it is still possible for someone with physical possession
of the media to recover the information that was formerly present.
This magnetic remanence, therefore, is a major vulnerability of any OA
System employing magnetic storage media. The threat corresponding to
this vulnerability is that persons may come into possession of
magnetic media which contain classified or sensitive, but
unclassified, information for which they are not authorized. The
general control to combat this is for all magnetic media to be
properly cleared or declassified before being released for reuse. The
following sections give general guidance in the areas of clearing and
declassifying magnetic storage media. For more detailed guidance,
please see the Department of Defense Magnetic Remanence Security
Guideline [4].
7.6.2 Clearing and Declassification of Magnetic Media
Clearing of magnetic media refers to a procedure by which the
classified information recorded on the media is removed, but the
totality of declassification is lacking. Clearing is a procedure used
when magnetic media will remain within the physical protection of the
facility in which it was previously used. Declassification refers to
a procedure by which all classified information recorded on magnetic
media can be totally removed. Declassification is required when
magnetic media which have ever contained classified data are to be
released outside of a controlled environment.
7.6.2.1 Clearing of Magnetic Media
Certain types of removable media (e.g., magnetic tapes, floppy disks,
cassettes, and magnetic cards) may be cleared by overwriting the
entire media one time with any one character. Floppy disks may be
cleared by applying a vendor's formatting program that overwrites each
location with a given character.
Fixed media (e.g., Winchester disks) should be cleared by overwriting
at least one time with any one character. One way to do this is by
applying a vendor-supplied formatting program that overwrites each
location on the disk with a given character, if it can be shown that
this program actually works as advertised. The user should beware:
some programs that purport to overwrite all locations do not actually
do this.
Cleared media may be reused within the controlled facility or released
for destruction; however, they should be marked and controlled at the
level of the most restrictive sensitivity of information ever
recorded.
7.6.2.2 Declassification of Magnetic Media
Certain types of removable media can be declassified using a
degaussing device that has been approved for declassifying media of
that type. (A list of approved devices is maintained by NSA.)
If a fixed medium (for example, a hard, or Winchester, disk) is
operative, an approved method of declassifying the disk pack is to
employ an overwrite procedure which must overwrite all addressable
locations at least three times by writing any character, then its
complement (e.g., binary ones and binary zeros) alternately.
When fixed media become inoperative, it is impossible to declassify
the media by the overwrite method. In this case, there are two
alternate procedures that may be used: (1) disassemble the disk pack,
and degauss each platter with the appropriate approved degaussing
equipment; and (2) courier the inoperative media to the vendor's
facility, have the magnetic media (e.g., disk platters) removed in
sight of the courier and returned to the courier for destruction at
the secure site. The vendor can then install new platters and repair
any other problems with the disk unit. See Reference 4 for a detailed
discussion of each of these alternatives.
7.6.3 Destruction of Magnetic Media
Magnetic media that have contained classified or sensitive, but
unclassified, information and are no longer useful should be
destroyed. Prior to destruction, all labels or other markings that
are indicative of classified or other sensitive, but unclassified, use
should be removed.
Detailed methods for destruction of different types of magnetic media
are given in Reference 4.
7.6.4 Media Encryption
Cryptography has important applications in an Office Automation
environment, since in many cases it is impossible to physically
protect magnetic media from all individuals who lack either the
clearance or need-to-know for all information contained on the
media[22]. (For example, if an OA System with fixed media is shared
by two or more users, there quite often is information for which one
user does not have a need-to-know that needs to be stored in the
system.) In these cases, the use of cryptography to help prevent
compromise of classified or sensitive, but unclassified, information
should be considered.
In many cases, information security can be enhanced if the information
is stored on the media in encrypted form. There are two strategies
which can be used: bulk file encryption and integral file encryption.
Each of these strategies has its advantages and disadvantages; see
Reference 23 for a description of each.
7.7 Environmental Considerations
Office Automation Systems are generally designed to be used in the
"typical" office environment[23]. Therefore, they seldom require
special environmental controls such as air conditioning or air
contamination controls. However, an OA System and its media can be
seriously damaged or even destroyed by such things as electrical
surges, fire, water, crumbs of food, termites, chemicals, or dust.
Since destruction of the system and/or information represents a
serious loss to the organization, it is imperative that steps be taken
to help prevent unnecessary damage to the OA System. The following
discussion is adapted from NBS Special Publication 500-120, Reference
23.
7.7.1 Electrical Power Quality
Surges in electrical power can cause a great deal of damage to an OA
System, and can cause information stored within to be permanently
inaccessible. Furthermore, frequent power outages cause the loss of
use of the system and its resources. Therefore, if the local power
supply quality is unusually poor (e.g., large fluctuations in voltage
or frequency, voltage spikes, or frequent outages), then such devices
as surge protectors, battery backup, or uninterruptible power supply
systems should be considered. In addition, disconnecting the system
should be considered during intense electrical storms.
7.7.2 Air Contaminants
The general cleanliness of the area in which OA Systems are operated
has an effect on reliability, both of the equipment and of the
magnetic storage media. Although it is generally not necessary to
install special-purpose air purifiers for the OA System, cutting down
or eliminating such contaminants as smoke and dust can only help the
OA System and its media. The best guidance that can be given in this
area is to keep smoke, dust, cigar and cigarette ashes, and similar
airborne contaminants as far away from the OA System as possible.
7.7.3 Fire Damage
Fire and excess heat can cause the destruction of an OA System in a
very short time. Therefore, any Office Automation equipment in the
office should be kept as far away from any open flames or other heat
sources as possible. In addition to this, all users of the system
should be familiar with procedures to be followed in case a fire
should break out. Fire protection equipment (e.g., extinguishers)
should be present and conveniently located so that the damage caused
by a fire is limited as much as possible[5].
7.7.4 Static Electricity
Another way in which Office Automation equipment can be damaged is by
static electricity. If the climate in a particular area results in
the presence of large amounts of static electricity, the use of anti-
static sprays, carpets or pads should be considered. In addition,
since static electricity can quite often build up in personnel,
particularly when carpeting is used, personnel can be instructed to
discharge any built-up static charge by simply touching a grounded
object, such as a metal desk or doorknob.
7.7.5 Other Environmental Considerations
There are other ways in which Office Automation equipment can be
damaged by environmental hazards. One of these is by the spillage of
food or liquid onto the equipment or media. Spilling a soft drink on
a keyboard, for example, can cause damage that requires extensive
repair or replacement of the keyboard. Spilling water or crumbs of
food onto a floppy disk can cause it to be unusable, possibly
resulting in the loss of information stored on it. Therefore, keep
all food and drinks away from Office Automation equipment and
media[5].
7.8 Preparing Downgraded Extracts
In some instances, it is operationally necessary to copy information
from a volume of media at one sensitivity level to another volume that
is at a lower sensitivity level. If the OA System does not meet the
requirements of at least Class B1, this is always dangerous, as
classified or sensitive, but unclassified, information could be
compromised without the user's knowledge. Therefore, any decision to
permit the electronic downgrading of information should be made only
after the risks of compromise have been carefully considered. The
person or organization making the decision should be willing to accept
the risk that classified or other sensitive, but unclassified,
information will be compromised.
Each ADPSSO is responsible for enforcing the procedures by which
downgrading of information can be done. The ADPSSO may also be
responsible for developing these procedures; however, they may be
dictated by organizational policy. The following method is
appropriate in some instances; however, the reader should again be
warned that the possibility of information compromise exists when this
is done:
(1) Format a new volume of media; make sure that it has never
been written on before. It would be best if the volume
could be removed from a sealed container (e.g., a new box
of diskettes).
(2) Copy the necessary information from its current location
to the new media.
(3) Carefully examine the new media. Look for any signs that
information other than what was intended has been copied.
If it is feasible, print out everything on the target
media, to verify that they contain no other information.
Of course, it is still possible that information could have been
copied onto the new media without being detected. However, if it is
necessary that downgrading be permitted, this is a risk that must be
taken.
PART IV:
GUIDANCE FOR OTHERS
8.0 RESPONSIBILITIES OF THE ORGANIZATION OWNING* THE OA SYSTEM
Good Information Security begins at the top levels of an organization.
If the organization has a commitment to Information Security, there is
a far better chance of a security program succeeding. In order to
foster good Office Automation System Security, and in turn good
Information Security, the following conditions should exist within the
organization (e.g., Department, Agency) that "owns" the OA system.
(1) The organization should have a comprehensive Information Security
policy. Further, the organization should have an AIS Security policy
that ensures the implementation of its Information Security policy for
information contained within or processed by AIS. In addition, the
organization should have an OA System Security policy that is
consistent with both its overall Information Security policy and its
AIS Security policy[5]. This OA System Security policy should
describe, at a minimum:
(a) What actions are permissible on an Office Automation
System, what information may be processed when and by
whom, and what is prohibited.
(b) What the organization permits regarding the use of
government-owned OA Systems offsite (e.g., at home, or
while traveling on official business), the use of
personally-owned OA Systems to do government work, and the
use of government-owned resources to do outside work
(e.g., schoolwork).
(c) Procedures for maintenance of OA Systems.
(d) Procedures for the proper secure operation of an OA
System.
(e) Procedures for the secure handling, marking, storage, and
disposal of classified or sensitive, but unclassified,
information handled by an OA System.
(2) The owning organization should set up a training program to
properly instruct users and security officers in the areas of
information security, including computer security and Office
Automation security. If each person that uses the OA System is
properly trained in the security aspects as well as the functional
aspects of the system, the chance of a security problem occurring
because of user error is significantly decreased.
____________________
* This section applies to any organization responsible for the
operation of an OA System, regardless of whether the system is owned,
leased, or otherwise obtained.
(3) The owning organization should have a policy concerning the
procurement and use of hardware/software. The organization is
responsible for ensuring that all copyrights and license agreements
are followed, and that no pirated or otherwise illegally obtained
software is used in its OA Systems. Furthermore, the organization
should set up a program to test newly purchased or developed software
prior to its use in operational systems. The purpose of this program
is to ascertain that the software works as advertised, and does not
contain trapdoors, Trojan horses, worms, viruses, or other malicious
code. (A program of this type is also an excellent way to detect bugs
in the software.)
(4) The owning organization should have a configuration management
program that maintains control over changes to the OA System. This
program can also maintain records of maintenance done to the system,
and keep an inventory of hardware and software to help detect
theft[5].
(5) The organization should have a policy covering whether or not
audit trails are required and what information is required to be
recorded.
(6) The organization should have a policy covering the certification
and accreditation of OA Systems that handle classified or sensitive,
but unclassified, information[9].
9.0 REQUIRING SECURITY IN THE PROCUREMENT OF OFFICE AUTOMATION
SYSTEMS
Security is an important consideration throughout the entire life-
cycle of an Office Automation System. If security is not considered
during the initial system specifications and Request for Proposal
(RFP), it may not be designed into the OA System, and will remain a
problem throughout the system life-cycle. Often, when deciding upon
what OA System to buy, security is ignored in favor of performance and
compatibility with other AIS. Security does not have to be
incompatible with other goals; therefore, ignoring it because of them
is not valid.
OMB Circular A-130 requires that a risk analysis be done by the person
or organization responsible for the security of any AIS before
procurement of the system is begun[13]. (Risk analyses are also
required at other times during the system life-cycle; see Reference 13
for further guidance.) This requirement applies as much to OA Systems
as to any other AIS.
This risk analysis, which may be anything from a very informal review
to a fully quantified risk analysis, should help identify potential
security problems. These problems can then be addressed before and
during the procurement of the system.
(Note: At this point, it is helpful to remind procurement officers
and security officers that the prospective vendor's security claims
should be verified to the greatest extent possible. Many times,
mechanisms or features claimed by vendors are either not present, or
are so easily subvertible that they are of little use.)
The following guidelines should be considered when writing system
specifications and Requests for Proposal.
9.1 Processing Classified Information: Policy Requirements
If the OA System will be processing classified information, it must
comply with the appropriate national TEMPEST policy directive[13,14].
The Request for Proposal must state that the system is to meet this
policy. Furthermore, if in addition to processing classified
information the OA System is to have a communications capability, then
appropriate Communications Security (COMSEC) measures, as approved by
the National Security Agency, must be taken. The RFP and the system
specification should require the capability to adapt to whatever
COMSEC measures will be used to protect the system's communications
(e.g., compatibility with cryptographic devices).
9.2 Physical Environment of the OA System
An OA System is generally considered to be a high-dollar asset. If
the OA System will be kept in an area that does not provide an
adequate level of protection against theft, then the purchase of
devices that lock the system to a table or in a closet should be
considered. Also, the use of OA Systems with the capability for
removable-media-only may be considered if there is a high probability
of vandalism to the system. If a system with fixed media were to be
vandalized, the information stored on the fixed media since the last
backup could also be lost, while information contained on removable
media can be protected by locking up the media. The probability of
vandalism cannot be appreciably lowered by this method, but the damage
caused by a vandal can be significantly lessened by protecting the
information.
If the OA System will be used to process classified information, and
will be kept in an area that is not approved for open storage of
information of that sensitivity, an OA System with removable-media-
only should be used. This will lessen the chance of compromise of
information if an unauthorized user were able to access the system, as
classified or sensitive, but unclassified, information could be
removed from the system and secured when the system is unattended.
A GSA-approved, tamper-resistant cabinet in which the entire system
can be secured should be purchased if the system will be used to
process classified information, will contain fixed media, and will be
kept in an area that is not approved for open storage of classified
information. Given this scenario, this cabinet is the only way in
which the security requirements of the system can be satisfied.
9.3 Identification of Non-Volatile Components
All components of the proposed OA System that are non-volatile (i.e.,
that retain information after power has been removed) should be
identified prior to procurement. If the OA System is identified as
having only removable media, and there is non-volatile memory that has
not been identified as such, then the OA System has been incorrectly
identified, since it contains a type of fixed media.
9.4 System Communications Capabilities
If it is known at the time of procurement that the OA System is to be
connected with other OA Systems to form a Local Area Network (LAN),
then the security requirements of the entire LAN must be considered
first. If the procurement is to be of the entire LAN (i.e., of all of
its components), then the issues in this chapter must be addressed for
the LAN as a whole, as well as for each of its components. Individual
nodes of the LAN may have different security requirements than other
nodes on the LAN.
If the procurement is to be for an OA System which is to be attached
to an existing LAN, then the security requirements and mechanisms of
the existing LAN must be examined prior to writing the specifications
of the OA System. The new OA System should support all security
mechanisms that already exist in the LAN, and should not allow a
violation of the LAN's security policy.
(Note: The LAN should enforce a security policy, as any AIS should.
This particular security policy should be driven by the owning
organization's overall Information Security Policy, and the particular
environment in which it operates. See Chapter 8.0 of this guideline
for a further discussion of security policies.)
If the OA System must be alternately connected as a terminal to
several different AIS that process different sensitivity levels of
information, the procurement should specify that only OA Systems using
removable-media-only shall be considered. Since the sensitivity level
of an OA System with fixed media cannot be easily lowered, switching
between AIS with different sensitivity levels of information is
impractical, if not impossible, for these systems.
9.5 Shared-Use Systems and Multi-User Systems
A "shared-use system" is an OA System that is used by more than one
person, but not by more than one at a time. A "multi-user system" is
an OA System that can be used by more than one person at a time.
Whenever an OA System is to be shared by more than one person, either
serially or simultaneously, there are security concerns which should
be addressed that do not occur if the OA System is used exclusively by
one person.
9.5.1 Shared-Use Systems Processing One Sensitivity Level of
Information
If the system is to be shared by several users, and not all users will
have the necessary clearances and need-to-know for all information
that will ever be processed or controlled by that OA System, the
possibility of acquiring an OA System that uses removable-media-only
should be investigated. With this type of system, information can be
removed and locked away to prevent its compromise.
If a system with fixed media is procured and used, any information
that is stored on fixed media may be accessible to all users of the
system. If some users of the OA System do not have a need-to-know for
some of the information stored on it, this access is contrary to the
provisions of the Privacy Act of 1974 [20] (See Section 3, paragraph
(b) of Reference 20). Therefore, if a system that contains fixed
media is to be used in this situation, it should meet the requirements
of at least class C2, when evaluated against the TCSEC.
9.5.2 Shared-Use Systems Processing Information of Multiple
Sensitivity Levels
In many cases, it is desirable to send machine-readable copies of
information processed on one OA System to another site for use (e.g.,
copy a file from one OA System onto a floppy disk, and then use that
floppy disk in another OA System). If this is the case, and if the OA
System will be used to process several different sensitivity levels of
information (e.g., Unclassified through TOP SECRET; personnel,
medical, and financial), an OA System that uses removable-media-only
should be used. An OA System with fixed media should not be used,
since the sensitivity level of the system may not be lowered, and
since any removable media which is inserted into an OA System with
fixed media must be regarded as having the same sensitivity level as
the system itself.
9.5.3 Shared-Use Systems and Multi-User Systems With Fixed
Media
If the OA System is to utilize fixed media, and it is desired that
users with differing clearances and/or need-to-know be able to access
the system, hardware/software security should be specified in the RFP.
Specifically, if some users of the OA System do not have a clearance
and/or a need-to-know for some of the information to be processed on
the system, the RFP should follow the guidance given in References 2
and 3. It is possible that no vendor will be able to respond to the
RFP, because there are currently no OA Systems available that meet
these requirements. If this occurs, the planned mode of operation of
the OA System should be revised to reflect the security capabilities
of those systems that are available.
9.5.4 Multi-User Systems Processing Information of Multiple
Sensitivity Levels
If it is desired that the OA System be able to simultaneously process
and store information of different sensitivity levels, and the system
must be trusted to maintain the separation of information by
sensitivity level, the specifications should require a system that
meets the recommendations given in References 2 and 3. If no vendor
is able to respond to the RFP because of lack of hardware/software
security controls, the planned mode of operation of the OA System
should be revised to reflect the security capabilities of those
systems that are available.
10.0 SECURE DISPOSAL OF OFFICE AUTOMATION SYSTEMS
When an Office Automation System has outlived its usefulness and has
become obsolete, or when it has become damaged beyond repair, it must
be disposed of properly. If the OA System has been used to process or
store classified or sensitive, but unclassified, information, certain
precautions should be taken before the system can be disposed of
through normal channels. These precautions will help to prevent the
compromise of any classified or sensitive, but unclassified,
information remaining in the system after it is beyond the control of
the organization that once used it.
10.1 Removable Media
Any removable media that were used in the OA System should be removed.
If these media will be used in another OA System without being
cleared, care must be taken to ensure that the new OA System is
approved for processing information of the removable media's
sensitivity level.
If it is desired that the removable media be reused in the same
facility (but after information currently stored on them is erased),
they may be cleared by one of the methods detailed in Reference 4.
In all other cases, removable media that once contained classified or
sensitive, but unclassified, information should be either declassified
or destroyed, as appropriate, using the methods detailed in Reference
4.
10.2 Fixed Media
Fixed media attached to the OA System that contain or formerly
contained classified or sensitive, but unclassified, information
should be declassified, destroyed, or removed from the system before
they leave the controlling organization. Declassification and
destruction procedures are described in Reference 4.
10.3 The Remainder of the OA System
Once both fixed and removable media have been removed from the system
and handled appropriately, any semiconductor memory that remains in
the system should be properly declassified. To declassify
semiconductor memory, the following procedures should be followed
prior to disconnecting the power supply. A random pattern of bits
must be written over each location. No further data is to be inserted
for a 24-hour period and the power is to remain on. This same
overwrite procedure should be used a second and third time, i.e.,
inserting a random pattern of bits and leaving the system powered up
for 24 hours, for a total of 72 hours, and no interim insertion of
bits. Upon completion of the third cycle, the memory will be
considered unclassified. As a second option, the security officer may
have the semiconductor memory removed from the OA system and destroyed
before the system leaves his control.
Users who cannot use either of these options should contact their
organization's Computer Security Office. Additional information is
also available from NSA, Ft. George G. Meade, MD 20755-6000, ATTN:
Division of Computer Security Standards.
APPENDIX
A Guideline on Sensitivity Marking of the Office Automation System and
Its Storage Media
Throughout this guideline, sensitivity marking of OA Systems
processing classified or sensitive, but unclassified, information and
of magnetic storage media is discussed. This appendix provides
guidance on how to mark the OA System and its media appropriately.
A.1 Sensitivity Marking of OA Systems Having Removable-Media-Only
The OA System and its peripheral devices must be clearly marked with
the highest sensitivity of information that it is allowed to
process[9,22]. Stickers indicating the highest sensitivity of
information that may be processed by that device should be applied
directly to the OA System and each peripheral device. Under normal
circumstances, this label should not be removed from the system.
An OA System with removable media (and with only volatile
semiconductor memory) is considered to have the same sensitivity level
as the media which are currently contained in it. Since OA Systems
that do not contain fixed media can change sensitivities (see Section
4.1.2.2), it is recommended that there be a clearly-visible sign
placed near the system that indicates when the OA System is being used
to process a specific type or range of information (e.g., classified,
personnel privileged, proprietary). In this manner, others in the
office can be forewarned not to allow visitors to wander about in the
vicinity of the OA System. (The user should be aware that this sign
might also have the effect of "advertising" the fact that classified
or sensitive, but unclassified, information is being processed. This
could draw unwanted attention from curious people. Again, the user
should be very careful that no one is looking at what is being done.)
A.2 Sensitivity Marking of OA Systems Containing Fixed Media
Any OA System on which classified or sensitive, but unclassified,
information is stored is considered to be a sensitive OA System. Any
sensitive OA System is assumed to have the same sensitivity level as
the highest classified or most sensitive information stored on it.
This includes systems with fixed media, as well as systems with
nonvolatile semiconductor memory. These systems must always be given
the same level of protection as any other information of that
sensitivity level[22].
There should be attached to the OA System and each peripheral device,
which is not physically collocated with it, a human-readable label
(e.g., a sticker) on which is clearly and legibly written the
sensitivity of the OA System. Under normal circumstances, this label
should never be removed. If the sensitivity level of the system or
device changes, a new label indicating the new sensitivity of the
system can be placed on top of the old one.
Because of the presence of the fixed media, the sensitivity level of
the OA System may never be decreased, unless the system is
declassified in accordance with Reference 4.
The label attached to a peripheral device (e.g., a laser printer) that
is shared among several OA Systems should indicate the highest (most
restrictive) sensitivity of information that may be sent to that
device.
A.3 Sensitivity Marking of Removable Storage Media
The sensitivity level of a volume of removable media is the same as
the most restrictive sensitivity level of information stored on that
volume. All information on a volume of removable media should be
regarded as being at the same sensitivity level (e.g., it is not
permissible to consider one file on a diskette to be TOP SECRET and
another file on the same diskette to be Unclassified).
There should be a human-readable label attached to the container of
each volume of removable media (e.g., the outside of a diskette, the
outside of a tape reel) that clearly indicates the current sensitivity
level of that volume of media[5,11,12,22,23]. Under normal
circumstances, this label should not be removed unless the volume of
media is declassified using procedures specified in Reference 4.
Labels should be color coded in accordance with applicable government
and agency or departmental standards.
Example: An orange label may be used to indicate a TOP
SECRET diskette, a red label indicates a SECRET
diskette, a blue label indicates CONFIDENTIAL, a purple
label means personnel data is contained on the diskette,
a grey label indicates "Company X Proprietary
Information," a green label may be used on a diskette
that contains unsensitive information only.
The volume of media should then be protected to a level that is at
least commensurate with this label.
Example: A floppy disk that is marked SECRET should be
given the same level of protection as a piece of paper
that is marked SECRET (e.g., stored in a GSA-approved
safe when not in use).
It is permissible to raise the sensitivity level of a volume of
media. When this happens, the label on the media should also be
changed. A new label indicating the higher sensitivity level may be
placed on top of the old label, or the old label may be removed before
the new label is applied.
It should not be permissible to decrease the sensitivity level of a
volume of media without first declassifying it using one of the
approved methods described in Reference 4.
Any volume of media which is in the OA System at the same time as
other media of a more restrictive sensitivity level should
automatically acquire that more restrictive sensitivity[16].
Example: If an Unclassified system disk is placed in
drive A of an OA System, with a TOP SECRET disk in drive
B, the system disk should be considered to be TOP SECRET
and protected as such. The reason for this is that the
average user has no way of being absolutely certain what
is being written on each disk, and must therefore guard
against the OA System writing to the wrong disk by
upgrading the sensitivity of the system disk.
Any volume of removable media that is not sealed in its original
package and is not labeled should be presumed to be at the same
sensitivity level as the OA System in which it is used[5,15]. If this
OA System can have a range of sensitivity levels (e.g., is a system
with removable-media-only), the volume of media should be considered
to have the same sensitivity level as the highest classified or most
sensitive information the system can process.
If there is an unsealed, unlabeled volume of media, and it cannot be
determined which (if any) OA System it has been used in, the media
should be considered to have the same sensitivity level as the highest
sensitivity level of any OA System that they could have been used in.
Example: Suppose that there are four OA Systems in the
same room. Three are Unclassified systems, while the
fourth is TOP SECRET. An unlabeled floppy disk is found
lying on top of a desk in this room, and it cannot be
determined in which, if any, of these four OA Systems
this particular floppy has been used. This floppy disk
should therefore be considered to be TOP SECRET.
A.4 Sensitivity Marking of Fixed Storage Media
All fixed media should be regarded as having the same sensitivity
level as the OA Systems to which they are attached.
Unless the OA System has been approved to simultaneously process
information of a range of sensitivity levels, all information on the
fixed media should be regarded as being at the same level: the
highest sensitivity level of any information on the media.
LIST OF ACRONYMS
ACRONYM EXPANSION
ADPSSO ADP System Security Officer
AIS Automated Information System
LAN Local Area Network
NACSI National Communications Security Instruction
NCSC National Computer Security Center
OA System Office Automation System
PC Personal Computer
TCSEC Department of Defense Trusted Computer System
Evaluation Criteria
WP Word Processor
GLOSSARY
ADP System Security Officer (ADPSSO)
The person who is nominally responsible for the secure
operation of an OA system.
Automated Information System (AIS)
An assembly of computer hardware, software, and firmware
configured in such a way that it can collect, communicate, compute,
process, disseminate, and/or control data.
Connected Office Automation System
An OA System that is electrically connected to one or more AIS.
The OA System may be used as a host, a file server, a terminal, or any
other component of a network.
Local Area Network
An interconnected group of OA Systems or system components that
are physically located within a small geographic area, such as a
building or campus.
Magnetic Remanence
A measure of the magnetic flux density remaining after removal
of an applied magnetic force. Can also mean any data remaining on ADP
storage media after removal of the power.
Multi-User System
An OA System that can be used by more than one person
simultaneously.
Non-removable Magnetic Media
Any magnetic media used for the storage of information that is
not designed to be regularly removed from the system. Examples of
non-removable media include fixed or "Winchester" disks. (This will
also be referred to as "fixed media" for short.)
Nonvolatile Memory
Memory contained within an Office Automation System that
retains its information after power has been removed.
Office Automation System
Any microprocessor-based AIS or AIS component that is commonly
used in an office environment. This includes, but is not limited to,
Personal Computers, Word Processors, printers, and file servers. It
does not include electric typewriters, photocopiers, and facsimile
machines.
Personal Computer (PC)
A microprocessor-based computer which is primarily intended to
be used by one person at a time. It is usually characterized by
relatively low cost and small physical size (usually small enough to
fit on a desk or table).
Physically Protected Communications Media
Any communications media to which physical access is
sufficiently controlled that the chance of compromise, improper
modification, or destruction of information is assumed to be zero.
Removable Magnetic Media
Any magnetic media used for the storage of information that is
designed to be frequently and easily removed from the Office
Automation System by a user. Examples of removable magnetic media
include floppy disks, removable hard disks (e.g., Bernoulli disks) and
magnetic tapes. (This will also be referred to as "removable media"
for short.)
Sensitive, but Unclassified Information
Information the disclosure, loss, misuse, alteration, or
destruction of which could adversely affect national security or other
Federal Government interests. National security interests are those
unclassified matters that relate to the national defense or the
foreign relations of the U.S. Government. Other government interests
are those related, but not limited to the wide range of government or
government-derived economic, human, financial, industrial,
agricultural, technological, and law enforcement information, as well
as the privacy or confidentiality of personal or commercial
proprietary information provided to the U.S. Government by its
citizens[19].
Sensitivity Label
The physical representation of the sensitivity level of information.
Sensitivity Level
A designation, associated with information, indicating (1) the
amount of harm that can be caused by the exposure of that information
to an unauthorized user, (2) any formal access approvals that must be
granted prior to the granting of access to that information, and (3)
any specific handling restrictions placed on that information.
Sensitivity levels contain both a hierarchical component (e.g.,
Unclassified, CONFIDENTIAL, SECRET, TOP SECRET) and a non-hierarchical
component (e.g., For Official Use Only (FOUO), Proprietary Information
Enclosed (PROPIN)).
Shared-Use System
An OA System that is used by more than one person, but is used
by only one person at a time.
Stand-Alone Office Automation System
An OA System that is electrically and physically isolated from
all other AIS.
Volatile Memory
Memory contained within an Office Automation System that loses
its information a short time after power has been removed.
Word Processor (WP)
An Office Automation System that is designed to be used
primarily in the preparation of documents containing alphanumeric
text.
Workstation
The total collection of Office Automation equipment, physically
located in one place, that makes up the resources meant to be used by
one person at a time.
REFERENCES
1. U.S. Air Force Computer Security Program Office, "Guidance
for Secure Operating Procedures for the Zenith Z-150
Personal Computer," 1 June 1985.
2. Department of Defense Standard 5200.28-STD, "Department of
Defense Trusted Computer System Evaluation Criteria," 26
December 1985.
(Note: this document is also referenced as: DoD Computer
Security Center, Department of Defense Trusted Computer
System Evaluation Criteria, CSC-STD-001-83, 15 August
1983.)
3. DoD Computer Security Center, Computer Security
Requirements--Guidance for Applying the Department of
Defense Trusted Computer System Evaluation Criteria in
Specific Environments, CSC-STD-003-85, 25 June 1985.
4. DoD Computer Security Center, Department of Defense Magnetic
Remanence Security Guideline, CSC-STD-005-85, 15 November
1985 (FOR OFFICIAL USE ONLY).
5. Department of Energy, "Security Guidelines for
Microcomputers and Word Processors," DOE/MA-0181,
March 1985.
6. Executive Order 12356, National Security Information,
6 April 1982.
7. Federal Emergency Management Agency, "Information Systems
Policy," Instruction 1500.3, 23 March 1984.
8. Federal Emergency Management Agency Manual 1540.2,
"Automated Information Systems (AIS) Security," September
1984.
9. Federal Information Processing Standards Publication (FIPS
PUB) 102, Guideline for Computer Security Certification and
Accreditation, 27 September 1983.
10. Department of the Interior, "Acquisition and Use of
Microcomputers," 376 DM 12.1.
11. Lawrence Livermore National Laboratory, "Computer Security
Guidelines for Microcomputer Users," January 1985.
12. Los Alamos National Laboratory, "Word Processor Security
Policy," June 1982.
13. Office of Management and Budget (OMB) Circular A-130,
"Management of Federal Information Resources,"
12 December 1985.
14. National COMSEC Instruction (NACSI) 5004, "TEMPEST
Countermeasures for Facilities Within the United States
(U)," 1 January 1984 (SECRET).
15. National COMSEC Instruction (NACSI) 5005, "TEMPEST
Countermeasures for Facilities Outside of the United States
(U)," 1 January 1984 (SECRET).
16. National Computer Security Center, Personal Computer
Security Considerations, NCSC-WA-002-85, December 1985.
17. National Security Decision Directive 145, National Policy on
Telecommunications and Automated Information Systems
Security, September 17, 1984.
18. National Telecommunications and Information Systems
Security Policy (NTISSP) No. 2, "National Policy on
Protection of Sensitive, but Unclassified Information in
Federal Government Telecommunications and Automated
Information Systems", 29 October 1986.
19. U.S. Nuclear Regulatory Commission, NRC Manual, Chapter
NRC-2301, "Systems Security", March 16, 1985.
20. Public Law 93-579, "Privacy Act of 1974," 31 December, 1974.
21. Schaefer, Marvin, "Security Vulnerabilities of Office
Automation Systems," in Proceedings of the Security Affairs
Support Association's Fall 1985 Symposium: "INFOSEC FOR THE
NINETIES", 21-22 November 1985.
22. Department of State, "Security Standards for Office
Automation Systems used for National Security Information in
the Washington, D.C. Metropolitan Area," A/ISS Systems
Security Standard Number 1, 22 December 1985.
23. Steinauer, Dennis D., Security of Personal Computer Systems:
A Management Guide, NBS Special Publication #500-120,
January 1985.
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