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__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
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INFORMATION BULLETIN
HP-UX vgdisplay Buffer Overrun Vulnerability
February 7, 1997 22:00 GMT Number H-27
______________________________________________________________________________
PROBLEM: A vulnerability exists in the vgdisplay(1M) program which is
part of the Logical Volume Manager subsystem.
PLATFORM: HP-UX 10.x.
DAMAGE: This vulnerability may allow local users to gain root
privileges.
SOLUTION: Until patches are available, it is recommended that sites take
the steps outlined in section 3 as soon as possible.
______________________________________________________________________________
VULNERABILITY Exploit details involving this vulnerability have been made
ASSESSMENT: publicly available.
______________________________________________________________________________
[ Start AUSCERT Advisory ]
===========================================================================
AA-97.04 AUSCERT Advisory
HP-UX vgdisplay Buffer Overrun Vulnerability
7 February 1997
Last Revised: --
- --------------------------------------------------------------------------
AUSCERT has received information that a vulnerability exists in the
vgdisplay(1M) program which is part of the Logical Volume Manager subsystem
under HP-UX 10.x.
This vulnerability may allow local users to gain root privileges.
Exploit information involving this vulnerability has been made publicly
available.
Currently there are no vendor patches available that address this
vulnerability. AUSCERT recommends that sites take the steps outlined in
section 3 as soon as possible.
This advisory will be updated as more information becomes available.
- --------------------------------------------------------------------------
1. Description
The HP-UX Logical Volume Manager (LVM) is a subsystem for managing
disk space. It comprises a number of auxiliary programs used to
create, display and manipulate the LVM information.
AUSCERT has received information that a vulnerability exists in the
vgdisplay(1M) program used to display information about LVM volume
groups.
Due to insufficient bounds checking on arguments which are supplied
by users, it is possible to overwrite the internal stack space of the
vgdisplay program while it is executing. By supplying a carefully
designed argument to the vgdisplay program, intruders may be able to
force vgdisplay to execute arbitrary commands. As vgdisplay is setuid
root, this may allow intruders to run arbitrary commands with root
privileges.
This vulnerability is known to affect HP-UX 10.x.
Note that many of the LVM utility programs are hard links to
vgdisplay(1M). This indicates that these utility programs share the
same code with vgdisplay, and may also be subject to similar attacks.
The following programs are all hard links: lvchange, lvcreate,
lvdisplay, lvextend, lvlnboot, lvreduce, lvremove, lvrmboot, pvchange,
pvcreate, pvdisplay, pvmove, vgcfgbackup, vgcfgrestore, vgchange,
vgcreate, vgdisplay, vgexport, vgextend, vgimport, vgreduce, vgremove,
vgscan.
By default, dynamically linked versions of the LVM programs are found
in /usr/sbin under HP-UX 10.x. Statically linked versions are also
available under HP-UX 10.x in /sbin.
Exploit information involving this vulnerability has been made
publicly available.
2. Impact
Local users may gain root privileges.
3. Workarounds/Solution
AUSCERT recommends that sites limit the possible exploitation of this
vulnerability by immediately removing the setuid permissions as stated
in Section 3.1.
Currently there are no vendor patches available that address this
vulnerability. AUSCERT recommends that official vendor patches be
installed when they are made available.
3.1 Remove setuid and non-root execute permissions
To prevent the exploitation of the vulnerability described in this
advisory, AUSCERT recommends that the setuid permissions be removed
from the vgdisplay program immediately. Note that permission changes
to vgdisplay will also affect those LVM utility programs which are
hard links to vgdisplay.
As the vgdisplay and related programs will no longer work for non-root
users, it is recommended that the execute permissions also be removed.
Sites will need to restrict permissions on both the dynamically linked
copies in /usr/sbin and the statically linked copies in /sbin.
First, restrict permissions on the copies in /usr/sbin. For example:
# ls -l /usr/sbin/vgdisplay
-r-sr-xr-x 23 root sys 376832 Jun 10 1996 /usr/sbin/vgdisplay
# chmod 500 /usr/sbin/vgdisplay
# ls -l /usr/sbin/vgdisplay
-r-x------ 23 root sys 376832 Jun 10 1996 /usr/sbin/vgdisplay
Second, restrict permissions on the copies in /sbin. For example:
# ls -l /sbin/vgdisplay
-r-sr-xr-x 23 root sys 606208 Jun 10 1996 /sbin/vgdisplay
# chmod 500 /sbin/vgdisplay
# ls -l /sbin/vgdisplay
-r-x------ 23 root sys 606208 Jun 10 1996 /sbin/vgdisplay
Note that this will remove the ability for any non-root user to run
vgdisplay or any of the LVM utility programs which are hard linked to
vgdisplay.
4. Previous patches
During the installation of HP-UX patches, copies of files being
replaced are saved in case the patches need to be backed out of. The
original versions of patched files are often stored in the following
location:
HP-UX 10.x: /var/adm/sw/patch/<PATCH_NAME>/
If patches for vulnerable programs have been previously installed,
copies of the vulnerable programs may be available in the above
location. Sites should ensure the directories have permissions
which restrict access to the patch areas.
5. Additional measures
Most Unix systems ship numerous programs which have setuid or
setgid privileges. Often the functionality supplied by these
privileged programs is not required by many sites. The large number
of privileged programs that are shipped by default are to cater for
all possible uses of the system.
AUSCERT encourages sites to examine all the setuid/setgid programs
and determine the necessity of each program. If a program does not
absolutely require the setuid/setgid privileges to operate (for
example, it is only run by the root user), the setuid/setgid
privileges should be removed. Furthermore, if a program is not
required at your site, then all execute permissions should be removed.
A sample command to find all setuid/setgid programs is (run as root):
# find / \( -perm -4000 -o -perm -2000 \) -exec ls -ld {} \;
It is AUSCERT's experience that many vulnerabilities are being
discovered in setuid/setgid programs which are not necessary for the
correct operation of most systems. Sites can increase their security
by removing unnecessary setuid/setgid programs.
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[ End AUSCERT Advisory ]
_______________________________________________________________________________
CIAC wishes to acknowledge the contributions of AUSCERT and Hewlett-Packard for
the information contained in this bulletin.
_______________________________________________________________________________
CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
National Laboratory in Livermore, California. CIAC is also a founding
member of FIRST, the Forum of Incident Response and Security Teams, a
global organization established to foster cooperation and coordination
among computer security teams worldwide.
CIAC services are available to DOE, DOE contractors, and the NIH. CIAC
can be contacted at:
Voice: +1 510-422-8193
FAX: +1 510-423-8002
STU-III: +1 510-423-2604
E-mail: ciac@llnl.gov
For emergencies and off-hour assistance, DOE, DOE contractor sites,
and the NIH may contact CIAC 24-hours a day. During off hours (5PM -
8AM PST), call the CIAC voice number 510-422-8193 and leave a message,
or call 800-759-7243 (800-SKY-PAGE) to send a Sky Page. CIAC has two
Sky Page PIN numbers, the primary PIN number, 8550070, is for the CIAC
duty person, and the secondary PIN number, 8550074 is for the CIAC
Project Leader.
Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.
World Wide Web: http://ciac.llnl.gov/
Anonymous FTP: ciac.llnl.gov (128.115.19.53)
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You will receive an acknowledgment containing address, initial PIN,
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PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
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This document was prepared as an account of work sponsored by an
agency of the United States Government. Neither the United States
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LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC)
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H-19: HP Software Installation Programs Vulnerability
H-20: Vulnerability in IRIX csetup
H-21: HP Security Vulnerabilities (newgrp, authentication, passwor
H-22: talkd Buffer Overrun Vulnerability
H-23: Sendmail MIME Conversion Buffer Overrun Vulnerability
H-24: IBM AIX(r) "gethostbyname()" Buffer Overrun Vulnerability
H-25: Vulnerability in rlogin/term
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Notes 10 - 6/16/95 PKZ300B Trojan, Logdaemon/FreeBSD, vulnerability
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