Signature Detail

HTTP: Multiple AV Vendor Invalid Archive Checksum Bypass

This signature detects attempts against a known vulnerability in the way multiple anti-virus products scan ZIP archive files. A malicious ZIP archive containing known trojans or viruses may be downloaded and stored on the local file system without the affected product raising a warning or otherwise informing the user of a potential threat. The product in such a case exhibits ineffective and misleading behavior.

Extended Description

Multiple antivirus products from various vendors are reported prone to a vulnerability that may allow potentially malformed ZIP archives to bypass detection. This issue arises when an affected application processes a ZIP archive with an invalid CRC-32 checksum. It should be noted that affected software may possibly detect a malicious file in the archive when it is decompressed or scanned manually. The discoverer of this vulnerability has reported that this issue affects H+BEDV AntiVir, AVG Anti-Virus, Sybari Antigen for Microsoft Exchange, and products by McAfee, and BitDefender. Symantec products were not found to be vulnerable to the issue. **Update: Symantec believes that the impact of this issue is low. This is because an archive handler processing an archive that possesses a corrupt CRC-32 checksum will fail, reporting that the archive is corrupt. This would mean that a malicious file contained in such an archive would not be directly accessible to a target recipient user. Alternatively, if the CRC-32 checksum is corrected manually by the recipient user and the file is extracted, it will likely be detected by client-side Anti-Virus solutions during the file extraction routine. This detection will likely occur before the malicious file is directly processed by the end user.

Affected Products

• AVG AVG Anti-Virus 7.1.308
• H+BEDV AntiVir Windows Workstation 6.30.0 .0.5
• McAfee VirusScan 4.0.0
• McAfee VirusScan 4.0.3
• McAfee VirusScan 4.5.0
• McAfee VirusScan 4.5.1
• Softwin BitDefender 7.0.0
• Sybari Software Antigen for Exchange 7.5.1314
• Symantec AntiVirus Corporate Edition 8.0.0 1
• Symantec AntiVirus Corporate Edition 8.0.0 1.425a/b
• Symantec AntiVirus Corporate Edition 8.0.0 1.429c
• Symantec AntiVirus Corporate Edition 8.0.0 1.501
• Symantec AntiVirus Corporate Edition 8.0.0 1.9374
• Symantec AntiVirus Corporate Edition 8.0.0 1.9378
• Symantec Norton AntiVirus Corporate Edition 8.0.0

References

• BugTraq: 12771