Clam AntiVirus Integer Overflow in Processing MEW Packed Files Lets Remote Users Execute Arbitrary Code
SecurityTracker Alert ID: 1019112|
SecurityTracker URL: http://securitytracker.com/id/1019112
(Links to External Site)
Updated: Dec 20 2007|
Original Entry Date: Dec 18 2007
Execution of arbitrary code via network, User access via network|
Fix Available: Yes Vendor Confirmed: Yes |
Version(s): prior to 0.92|
A vulnerability was reported in Clam AntiVirus. A remote user can cause arbitrary code to be executed on the target user's system.|
A remote user can create a specially crafted PE file packed with the MEW packer that, when processed by the target application, will trigger an integer overflow and execute arbitrary code on the target system. The code will run with the privileges of the target application.
The vendor was notified on October 17, 2007.
iDefense reported this vulnerability.
A remote user can create a file that, when processed by the target user or application, will execute arbitrary code on the target system.|
The vendor has issued a fixed version (0.92).|
The ClamAV advisory is available at:
Vendor URL: www.clamav.net/ (Links to External Site)
|Underlying OS: Linux (Any), UNIX (Any)|
Source Message Contents
Subject: iDefense Security Advisory 12.18.07: ClamAV libclamav MEW PE File|
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.
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