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The Computer Incident Advisory Capability
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INFORMATION BULLETIN
VAX/VMS Security Vulnerability in MONITOR
August 24, 1992, 1200 PDT Number C-30
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PROBLEM: The MONITOR utility on VMS versions 5.0 thru 5.4-2 can be
used to obtain unauthorized privileges.
PLATFORM: VAX systems running the VMS operating system.
DAMAGE: An unprivileged user can obtain all privileges.
SOLUTION: Upgrade to VMS version 5.4-3 (or higher); alternatively
disable or restrict access to MONITOR.
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Critical Information About MONITOR Vulnerability
CIAC is forwarding Digital Equipment Corporation's Software
Security Response Team's (SSRT) advisory regarding this
problem. While CIAC believes the information contained to
be accurate, SSRT is fully responsible for its contents. DEC
requires its advisory be redistributed intact.
CIAC and DEC recommend upgrading VMS to the latest version.
However, if you are unable to upgrade, there is a
workaround described in the following DEC Advisory:
===============================================================================
SSRT-0200 PROBLEM: Potential Security Vulnerability Identified in MONITOR
SOURCE: Digital Equipment Corporation
AUTHOR: Software Security Response Team - U.S.
Colorado Springs USA
PRODUCT: VMS
Symptoms Identified On: VMS, Versions 5.0, 5.0-1, 5.0-2, 5.1, 5.1-B,
5.1-1, 5.1-2, 5.2, 5.2-1, 5.3,
5.3-1, 5.3-2, 5.4, 5.4-1, 5.4-2
*******************************************************
SOLUTION: This problem is not present in
VMS V5.4-3 (released in October 1991) through
VMS V5.5-1 (released in July, 1992).
*******************************************************
Copyright (c) Digital Equipment Corporation, 1992 All Rights Reserved.
Published Rights Reserved Under The Copyright Laws Of The United States.
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PROBLEM/IMPACT:
-------------------------------------------------------------------------------
Unauthorized privileges may be expanded to authorized users of a system
under certain conditions, via the MONITOR utility. Should a system be
compromised through unauthorized access, there is a risk of potential
damage to a system environment. This problem will not permit unauthorized
access entry, as individuals attempting to gain unauthorized access will
continue to be denied through the standard VMS security mechanisms.
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SOLUTION:
-------------------------------------------------------------------------------
This potential vulnerability does not exist in VMS V5.4-3
(released in October 1991) and later versions of VMS through V5.5-1.
Digital strongly recommends that you upgrade to a minimum of VMS V5.4-3,
and further, to the latest release of VMS V5.5-1 (released in July, 1992).
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INFORMATION:
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If you cannot upgrade at this time, Digital recommends that you
implement a workaround (examples attached below) to avoid any potential
vulnerability.
As always, Digital recommends that you periodically review your system
management and security procedures. Digital will continue to review and
enhance the security features of its products and work with customers to
maintain and improve the security and integrity of their systems.
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WORKAROUND
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A suggested workaround would be to remove the installed image
SYS$SHARE:SPISHR.EXE via VMS INSTALL and/or restrict the use of
the MONITOR utility to "privileged" system administrators.
Below are the examples of doing both.
[1] To disable the MONITOR utility the image SYS$SHARE:SPISHR.EXE should be
deinstalled from a privileged account.
For cluster configurations;
---------------------------
$ MC SYSMAN
SYSMAN> SET ENVIRONMENT/CLUSTER
SYSMAN> DO INSTALL REMOVE SYS$SHARE:SPISHR.EXE
SYSMAN> DO RENAME SYS$SHARE:SPISHR.EXE SPISHR.HOLD
SYSMAN> EXIT
For non-VAXcluster configurations;
---------------------------------
$ INSTALL
INSTALL> REMOVE SYS$SHARE:SPISHR.EXE
INSTALL> EXIT
$ RENAME SYS$SHARE:SPISHR.EXE SPISHR.HOLD
[2] If you wish to restrict access to the MONITOR command so that only a
limited number of authorized (or privileged) persons are granted access
to the utility, one method might be to issue the following commands
from a privileged account;
For cluster configurations;
---------------------------
$ MC SYSMAN
SYSMAN> SET ENVIRONMENT/CLUSTER
SYSMAN> DO INSTALL REMOVE SYS$SHARE:SPISHR.EXE
SYSMAN> DO SET FILE/ACL=(ID=*,ACCESS=NONE) SYS$SHARE:SPISHR.EXE
SYSMAN> DO SET FILE/ACL=(ID=SYSTEM,ACCESS=READ+EXECUTE) SYS$SHARE:SPISHR.EXE
SYSMAN> DO INSTALL ADD SYS$SHARE:SPISHR.EXE/OPEN/HEADER/SHARE/PROTECT
SYSMAN> EXIT
$
THIS WILL IMPACT the MONITOR UTILITY FOR REMOTE MONITORING.
LOCAL USE OF MONITOR WILL CONTINUE TO WORK FOR PERSONS HOLDING
THE ID's GRANTED ACL ACCESS.
see additional note(s) below
For non-VAXcluster configurations;
----------------------------------
$ INSTALL
INSTALL> REMOVE SYS$SHARE:SPISHR.EXE
INSTALL> EXIT
$ SET FILE /ACL=(ID=*,ACCESS=NONE) SYS$SHARE:SPISHR.EXE
$ SET FILE /ACL=(ID=SYSTEM,ACCESS=READ+EXECUTE) SYS$SHARE:SPISHR.EXE
$ INSTALL
INSTALL> ADD SYS$SHARE:SPISHR.EXE/OPEN/HEADER/SHARE/PROTECT
INSTALL> EXIT
$
NOTE in the above examples: The "SET FILE /ACL" line should be repeated
for all accounts that are required/allowed to use the DCL MONITOR
command. The ID -SYSTEM- should be replaced with valid user ID's
that are to be associated with accounts you wish to grant access to.
End of DEC Advisory
===============================================================================
If you require additional assistance or wish to report a vulnerability,
call CIAC at (510) 422-8193/FTS or send e-mail to ciac@llnl.gov.
FAX messages to: (510) 423-8002/FTS.
For emergencies only, call 1-800-SKYPAGE and enter PIN number
855-0070 (primary) or 855-0074 (secondary).
The CIAC Bulletin Board, Felicia, can be accessed at 1200 or 2400
baud at (510) 423-4753/FTS and 9600 baud at (510) 423-3331/FTS.
Previous CIAC bulletins and other information is available via
anonymous ftp from irbis.llnl.gov (ip address 128.115.19.60).
CIAC wishes to thank Rich Boren of DEC's SSRT for assistance and
the advisory used in this bulletin.
PLEASE NOTE: Many users outside of the DOE and ESnet computing
communities receive CIAC bulletins. If you are not part of these
communities, please contact your agency's response team to report
incidents. Some of the other teams include the NASA NSI response
team, DARPA's CERT/CC, NAVCIRT, and the Air Force response team.
Your agency's team will coordinate with CIAC.
This document was prepared as an account of work sponsored by an agency
of the United States Government. Neither the United States Government
nor the University of California nor any of their employees, makes any
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