-----BEGIN PGP SIGNED MESSAGE-----
AUSCERT External Security Bulletin Redistribution
ESB-2007.1021 -- [UNIX/Linux]
ClamAV libclamav MEW PE File Integer Overflow Vulnerability
19 December 2007
AusCERT Security Bulletin Summary
Operating System: UNIX variants (UNIX, Linux, OSX)
Impact: Execute Arbitrary Code/Commands
Denial of Service
CVE Names: CVE-2007-5759
- --------------------------BEGIN INCLUDED TEXT--------------------
iDefense Security Advisory 12.18.07
Dec 18, 2007
Clam AntiVirus is a multi-platform anti-virus toolkit released under the
GNU Public License. ClamAV is often integrated into e-mail gateways and
used to scan e-mail messages for viruses. PE, or portable executable,
is the executable file format on Microsoft Windows systems. MEW is one
of the many executable packers that is supported by ClamAV. More
information can be found on the vendor's website at the following URL.
Remote exploitation of an integer overflow vulnerability in Clam
AntiVirus' ClamAV, as included in various vendors' operating system
distributions, allows attackers to execute arbitrary code with the
privileges of the affected process.
The vulnerability exists within the code responsible for parsing PE
files packed with the MEW packer. During unpacking, two untrusted
values are taken directly from the file without being validated. These
values are later used in an arithmetic operation to calculate the size
used to allocate a heap buffer. This calculation can overflow,
resulting in a buffer of insufficient size being allocated. This later
leads to arbitrary areas of memory being overwritten with attacker
Exploitation of this vulnerability results in the execution of arbitrary
code with the privileges of the process using libclamav.
In the case of the clamd program, this will result in code execution
with the privileges of the clamav user. Unsuccessful exploitation
results in the clamd process crashing.
iDefense has confirmed the existence of this vulnerability in ClamAV
0.91.2. Previous versions may also be affected.
Disabling the scanning of PE files will prevent exploitation. If using
clamscan, this can be done by running clamscan with the '--no-pe'
option. If using clamdscan, set the 'ScanPE' option in the clamd.conf
file to 'no'.
VI. VENDOR RESPONSE
The ClamAV team has addressed this vulnerability within version 0.92.
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-5759 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
VIII. DISCLOSURE TIMELINE
10/17/2007 Initial vendor notification
10/18/2007 Initial vendor response
12/18/2007 Coordinated public disclosure
The discoverer of this vulnerability wishes to remain anonymous.
Get paid for vulnerability research
Free tools, research and upcoming events
X. LEGAL NOTICES
Copyright © 2007 iDefense, Inc.
Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDefense. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically,
please e-mail email@example.com for permission.
Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct,
indirect, or consequential loss or damage arising from use of, or
reliance on, this information.
- --------------------------END INCLUDED TEXT--------------------
You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to firstname.lastname@example.org
and we will forward your request to the appropriate person.
NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members. As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.
NOTE: This is only the original release of the security bulletin. It may
not be updated when updates to the original are made. If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.
Contact information for the authors of the original document is included
in the Security Bulletin above. If you have any questions or need further
information, please contact them directly.
Previous advisories and external security bulletins can be retrieved from:
If you believe that your computer system has been compromised or attacked in
any way, we encourage you to let us know by completing the secure National IT
Incident Reporting Form at:
Australian Computer Emergency Response Team
The University of Queensland
Internet Email: email@example.com
Facsimile: (07) 3365 7031
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AusCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for member emergencies only.
-----BEGIN PGP SIGNATURE-----
-----END PGP SIGNATURE-----