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ITL Bulletin for August 2006

ITL Bulletin for August 2006
ITL Bulletin for August 2006

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Forwarded from: Elizabeth Lennon 



Shirley Radack, Editor
Computer Security Division
Information Technology Laboratory
National Institute of Standards and Technology
Technology Administration
U.S. Department of Commerce

Information systems capture, process, and store information using a
wide variety of media.  Information is recorded on data storage media
and on the devices that create, process, or transmit the information.
This information must be protected from creation to disposal in a way
that is appropriate to the sensitivity and value of the information.
When they discard media and devices, organizations and individuals
should make sure that proper techniques are used to remove the data,
or to destroy the media, to protect the confidentiality of the

Media sanitization is the process for removing confidential data from
storage media, with reasonable assurance that the data cannot be
retrieved and reconstructed. Data that has been improperly or
unsuccessfully removed from media could be recreated by attackers or
by unauthorized individuals. The sanitization process is especially
critical when storage media are transferred, become obsolete, are no
longer usable, or are no longer required by an information system. All
of the residual magnetic, optical, or electrical representation of
data that has been deleted from the media must not be easily

NIST Special Publication 800-88, Guidelines for Media Sanitization

NIST's Information Technology Laboratory recently issued Special
Publication (SP) 800-88, Guidelines for Media Sanitization:  
Recommendations of the National Institute of Standards and Technology,
to help organizations securely manage the information processed and
stored on devices and media. Authors Matthew Scholl, Richard Kissel,
Steven Skolochenko, and Xing Li discuss in detail the decision process
concerning media that has been identified for disposal or reuse, and
media that is no longer under the effective control of the
organization.  The guide, used along with local policies and
procedures, will enable managers to make effective, risk-based
decisions for the effective sanitization of the information recorded
on the media and for the disposal of the media.  Publication of the
guide was supported by the Department of Homeland Security (DHS).

NIST SP 800-88 discusses the basic types of information, the available
sanitization methods, and the different types of media, and provides
information on techniques for removing data and disposing of media.
The guide gives details on the procedures and principles that
influence sanitization decisions and includes a decision matrix to aid
the decision-making process. The appendices include tables of minimum
recommended sanitization techniques for clearing, purging, or
destroying various media. These tables can be used with the decision
flowchart to identify the needed steps for secure media handling. Also
included in the appendices are a glossary of terms, a listing of tools
and resources that can assist in decisions about media sanitization,
information about media sanitization specifically targeted to home
computer users, and a list of references.

The guide can be accessed at 

The Process for Managing Media Sanitization

An important step that federal organizations should take to securely
manage their information and media is to categorize their IT systems
in accordance with Federal Information Processing Standard (FIPS) 199,
Standards for Security Categorization of Federal Information and
Information Systems. FIPS 199 requires agencies to categorize their
information systems as low-impact, moderate-impact, or high-impact for
the security objectives of confidentiality, integrity, and
availability. The standard defines these three levels of impact as the
potential impact on the organization should there be a breach of
security (a loss of confidentiality, integrity, or availability).
Based on the results of categorization, organizations should then
select appropriate controls to protect their systems and information.
The needed controls are discussed in NIST SP 800-53, Recommended
Security Controls for Federal Information Systems.

The critical factors affecting information disposition and media
sanitization should be determined at the starting phase of system
development, when the system security plan is developed. For
information about developing security plans, see NIST SP 800-18, Guide
for Developing Security Plans for Federal Information Systems.

The initial system requirements should include hardware and software
specifications as well as interconnections and data flow documents
that will assist the system owner in identifying the types of media
used in the system. Decisions made at this time affect the resources
needed for sanitization for the remainder of the system life cycle.

A determination should be made during the requirements phase of system
development about what other types of media will be used to create,
capture, or transfer information used by the system. This analysis,
balancing business needs and risk to confidentiality, helps the
organization determine the media that will be considered for the
system. FIPS 200, Minimum Security Requirements for Federal
Information and Information Systems, assists organizations in the
risk-based analysis of security requirements.

Once an organization has completed an assessment of its system
confidentiality, determined the need for information sanitization, and
determined the types of media used and the media disposition, an
effective, risk-based decision can be made on the appropriate and
needed level of sanitization.

The organization should document decisions about sanitization of media
and ensure that a process and proper resources are in place to support
these decisions. Information disposition and sanitization decisions
occur throughout the system life cycle. During the life of an
information system, many types of media, containing data, will be
transferred outside the control of the system. Some media will be
reused during all of the stages of the system life cycle. These
conditions reflect the changing requirements for media during
activities such as system maintenance, upgrades to systems, and
configuration updates.

Frequently, the sanitization of media and the disposition of
information are carried out during the last phase of the system life
cycle. At this phase, decisions about media sanitization should be
made before disposal or release of the media for reuse outside the
organization, or the media should be destroyed.

Decisions about the proper sanitization methods for information should
be based on the level of confidentiality of the information that is
placed on the media. The electronic media used in today=C2=92s IT systems
are assumed to contain information that corresponds to the system=C2=92s
security categorization for confidentiality.

Other issues to be considered in decisions about media sanitization
include federal agency requirements for the retention of records and
for maintenance of records. Agency officials responsible for
implementing Privacy Act and, Freedom of Information Act (FOIA)
functions should be consulted. Officials responsible for maintaining
an agency=C2=92s historical information should also be consulted. These
consultations should be ongoing, as controls may have to be adjusted
as the system and its environment change.

Organizations should track, document, and verify media sanitization
and destruction actions, and periodically test the sanitization
equipment and procedures to ensure correct performance.

NIST SP 800-88 recommends that organizations establish an information
security governance structure for its media sanitization decisions.  
The guide describes the security responsibilities of everyone in the
organization=C2=ADfrom program managers and agency heads to users.

Media types are expected to change as the technology changes. However,
the process for media sanitization should always focus on protecting
the information that is recorded on the media.

Methods for Media Sanitization

After organizations have categorized their information, assessed the
nature of the medium on which it is recorded, assessed the risk to
confidentiality, and determined their future plans for the media, they
can then decide on the appropriate process for sanitization.  Factors
to be considered in sanitization are cost, environmental impact, and
the need to protect the confidentiality of the information.

There are two primary types of media:

* Hard copy media are physical representations of information, such as
  paper printouts, printer, and facsimile ribbons, drums, and platens.  
  Disposal of these types of media is often uncontrolled, leading to
  potential significant vulnerabilities if the information is 
  improperly disclosed.

* Electronic media are the bits and bytes contained in hard drives,
  random access memory (RAM), read-only memory (ROM), disks, memory
  devices, phones, mobile computing devices, networking equipment, and
  many other types of electronic equipment.

The methods of media sanitization are:

* Disposal of the media, by discarding the media without any
  sanitization procedures.  Processes include the recycling of paper 
  and other media that do not contain confidential information.

* Clearing the media by deleting information using methods that
  prevent retrieval by data, disk, or file recovery utilities, and 
  that resist keystroke recovery attempts executed from standard input
  devices and from data scavenging tools. Overwriting is an acceptable
  method for clearing media and protecting the confidentiality of the
  information. Software and hardware products are available to 
  overwrite storage space on the media with nonsensitive data. The 
  logical storage location of a file, such as the file allocation 
  table, as well as all addressable locations can be overwritten, 
  replacing the written data with random data. Overwriting cannot be 
  used for media that are damaged or that are not suitable for 

* Purging the media to protect the confidentiality of information
  against a laboratory attack, such as the use of signal processing
  equipment by specially trained personnel to recover data. Degaussing
  is a purging method that exposes the magnetic media to a strong
  magnetic field from a permanent magnet or electromagnetic coil to
  disrupt the recorded magnetic domains. Degaussing can be an 
  effective method for purging damaged media, for purging media with 
  exceptionally large storage capacities, or for quickly purging 
  diskettes. Degaussing cannot be used to purge nonmagnetic media, 
  such as compact disks (CDs) or digital versatile discs (DVDs).

* Destroying the media to prevent its reuse.  Destruction techniques
  include disintegration, incineration, pulverization, and melting of
  the media. Paper and flexible diskettes that have been removed from
  their outer containers can be shredded to an appropriate shred size 
  so that the information cannot be reconstructed. Sanding the media 
  by applying an abrasive tool and treating the surface with chemicals 
  can also be used to completely remove the media recording surface.  
  Optical mass storage media, including compact disks (CDs, CD-RW, 
  CD-R, CD-ROM), optical disks (DVDs), and magneto-optic (MO) disks 
  must be destroyed by burning, pulverizing, crosscut shredding, or 
  grinding the information-bearing surface. These processes should be 
  carried out by trained and authorized personnel at an approved 

If it is not practical to use the clearing and purging methods, then
destruction of the media is recommended. For example, paper media of
moderate confidentiality cannot be purged; therefore, the media should
be destroyed.

See NIST SP 800-88 for details on all of these methods.

Other Guidance and Standards Supporting the Secure Handling of

Some of the NIST publications that support the secure handling of
information and media sanitization include:

Federal Information Processing Standard (FIPS)  199, Standards for
Security Categorization of Federal Information and Information
Systems, provides guidance for establishing the security
categorization for a system=C2=92s confidentiality.  This categorization
will impact the level of assurance an organization should require in
making sanitization decisions.

FIPS 200, Minimum Security Requirements for Federal Information and
Information Systems, sets a base of security requirements that enables
an organization to have an effective media sanitization program.

NIST SP 800-18, Guide for Developing Security Plans for Federal
Information Systems, assists organizations in developing security
plans that summarize the security requirements for each information
system, and the security controls in place or planned for meeting the

NIST SP 800-30, Risk Management Guide for Information Technology
Systems, provides guidance to organizations in identifying the risks
to their information systems, assessing the risks, and taking steps to
reduce the risks to an acceptable level. The risk management process
enables organizations to protect the information systems that store,
process, and transmit organizational information, to make
well-informed risk management decisions, and to apply system
authorization and accreditation processes.

NIST SP 800-36, Guide to Selecting Information Technology Security
Products, provides information on commercial products that can be used
for clearing, purging, and destroying media.

NIST SP 800-53, Recommended Security Controls for Federal Information
Systems, provides information about minimum recommended security
controls to protect the confidentiality, integrity, and availability
of information systems and information, including the controls for
media protection and sanitization. The controls are administrative,
operational, and technical safeguards that are selected, based on the
system security categorization.

NIST SP 800-60, Guide for Mapping Types of Information and Information
Systems to Security Categories, assists organizations in identifying
information types and impact levels, and assigning impact levels for
confidentiality, integrity, and availability. The impact levels are
based on the security categorization definitions in FIPS 199.

These and other NIST publications can help you in planning and
implementing a comprehensive approach to IT security. Information
about the NIST publications that are referenced in this bulletin, as
well as other security-related publications, is available at 

Any mention of commercial products or reference to commercial
organizations is for information only; it does not imply
recommendation or endorsement by NIST nor does it imply that the
products mentioned are necessarily the best available for the purpose.

Elizabeth B. Lennon
Information Technology Laboratory
National Institute of Standards and Technology
100 Bureau Drive, Stop 8900
Gaithersburg, MD 20899-8900
Telephone (301) 975-2832
Fax (301) 975-2378

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