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SYNTHESIS OF THE VULNERABILITY

An attacker can create an archive containing a virus, which is not
detected by Avast Antivirus.

Severity: 1/4

Creation date: 21/03/2012

IMPACTED PRODUCTS

– Avast Antivirus

DESCRIPTION OF THE VULNERABILITY

Tools extracting archives accept to extract archives which are
slightly malformed. However, Avast Antivirus does not detect
viruses contained in these archives.

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 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/Avast-Antivirus-bypassing-via-RAR-TAR-11479