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Re: [Full-disclosure] Multiple AV Vendor Incorrect CRC32 Bypass Vulnerability.



Hi, I saw this behaviour last week with the virus "MyDoom.BE".
I use the mail gateway with Clamav/Amavis. Clamav doesn't detect the virus embeded in the zip file (with a crc broken).
But, Trendmicro detects it.


Fred.

bipin gautam wrote:
Multiple AV Vendor Incorrect CRC32 Bypass
Vulnerability.

Affected Product:
AVG 718
Sybari (Antigen for M$ exchange) 7.5.1314
Symantec 8.0
McAfee 4442
BitDefender 7.0


Description: if you create a zip archive with invalid CRC checksum...... some AV skip scanning the archive marking it as clean........ by this way, you can bypass antivirus gateways and slip in any attachment without scanning the archive. Moreover, these days.... software tools automatically repair a *broken* archive.

Vendor notification: I've lost faith in responsible
disclosure... long ago! Moreover, vendors don't
respond in timely manner.

regards,
Bipin Gautam
http://www.geocities.com/visitbipin/


Disclaimer: The information in the advisory is believed to be accurate at the time of printing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect or consequential loss or damage arising from use of, or reliance on this information.


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--
_______________________________________
Frederic Charpentier - Xmco Partners
Security Consulting / Pentest
web  : http://www.xmcopartners.com

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