Vigil@nce - ClamAV: bypassing via CHM, RAR, TAR
March 2012 by Vigil@nce
This bulletin was written by Vigil@nce : http://vigilance.fr/offer
SYNTHESIS OF THE VULNERABILITY
An attacker can create an archive containing a virus, which is not
detected by ClamAV.
Severity: 1/4
Creation date: 21/03/2012
IMPACTED PRODUCTS
– Clam AntiVirus
DESCRIPTION OF THE VULNERABILITY
Tools extracting archives accept to extract archives which are
slightly malformed. However, ClamAV rejects these malformed
archives, and does not detect included viruses.
A TAR archive containing "[aliases]" as its first 9 bytes bypasses
the detection. [severity:1/4; BID-52572, CVE-2012-1419]
A RAR archive containing "MZ" as its first 2 bytes bypasses the
detection. [severity:1/4; BID-52612, CVE-2012-1443]
A TAR archive with a large size bypasses the detection.
[severity:1/4; BID-52610, CVE-2012-1457]
A CHM help file with a header containing a low "interval" value
bypasses the detection. [severity:1/4; BID-52611, CVE-2012-1458]
A TAR archive with a header containing a large value bypasses the
detection. [severity:1/4; BID-52623, CVE-2012-1459]
An attacker can therefore create an archive containing a virus
which is not detected by the antivirus, but which is extracted by
extraction tools. The virus is then detected once it has been
extracted on victim’s computer.
ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN
http://vigilance.fr/vulnerability/ClamAV-bypassing-via-CHM-RAR-TAR-11467