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Vigil@nce - F-Secure Anti-Virus: bypassing via ELF, EXE, RAR, TAR
April 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 or a program containing a virus, which is not detected by F-Secure Anti-Virus.
Severity: 2/4
Creation date: 21/03/2012
IMPACTED PRODUCTS
F-Secure Anti-Virus
DESCRIPTION OF THE VULNERABILITY
Tools extracting archives (RAR, TAR, etc.) accept to extract archives which are slightly malformed. Systems also accept to execute programs (ELF, EXE) which are slightly malformed. However, F-Secure Anti-Virus does not detect viruses contained in these archives/programs.
An ELF program containing "ustar" at offset 257 bypasses the detection. [severity:2/4; BID-52581, CVE-2012-1429]
An ELF program containing "\19\04\00\10" at offset 8 bypasses the detection. [severity:2/4; BID-52589, CVE-2012-1430]
An ELF program containing "\4a\46\49\46" at offset 6 bypasses the detection. [severity:2/4; BID-52591, CVE-2012-1431]
An EXE program containing a large "class" field bypasses the detection. [severity:2/4; BID-52598, CVE-2012-1442]
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 header containing a large value bypasses the detection. [severity:1/4; BID-52623, CVE-2012-1459]
A TAR+GZ archive containing two streams bypasses the detection. [severity:1/4; BID-52626, CVE-2012-1461]
An ELF program with a changed 5th byte bypasses the detection. [severity:2/4; BID-52614, CVE-2012-1463]
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. An attacker can also create a program, containing a virus which is not detected by the antivirus, but which can be run by the system.
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