|
Actually by removing the file name size
you made the Eicar.com invalid. Antigen does scan this file and when it
extracts the eicar.com.txt we get a [EMAIL PROTECTED](P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TE
in the text file rather then a valid eicar. Since you made the name length a zero
when pasred the name of the zipped file becomes part of the file and the info
at the end is truncated making the file if it was viral, non-viral or if it
were able to be executed after this process is done it would be an invalid
application and it would not be executed. I used ziprepairpro and came up with
the same results. If a file filter is set up for exe, pif
,scr ect we will remove the file from the zip and rewrite it with a txt file
that can be extracted and read. If a doc file is put into a zip of this nature
with an embedded eicar in it we do detect the ecar as long as there is info
after the embedded file to be truncated.
Email: [EMAIL PROTECTED] MSN IM:[EMAIL PROTECTED] (email never
checked) -----Original Message----- From:
[EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
On Behalf Of bipin gautam Sent: Wednesday, March 09,
2005 9:37 PM Cc: [EMAIL PROTECTED] Subject: [Full-disclosure]
Multiple AV Vendor Incorrect CRC32 BypassVulnerability. Multiple AV Vendor Incorrect
CRC32 Bypass Vulnerability. Affected Product: AVG 718 Sybari (Antigen for M$
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. __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo!
Mail has the best spam protection around http://mail.yahoo.com
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