BugTraq
Unfiltered escape sequences in filenames contained in ZIP archives wouldn't be escaped on displaying or logging, and can also lead to bypass AV scanning Mar 14 2005 02:21PM
Dr. Peter Bieringer (pbieringer aerasec de)
Hello,

during investigation of Sober.l we got the idea to replace the spaces of a
filename contained in the ZIP archive by some escape sequences.

Many AV software is logging such filenames during decompressing, so after
creating such regular ZIP archive (by using Perl Archive::Zip module, no
other tweaks!) we've found that some of the tested products do not filter
or replace the escape sequences, which leads to funny results during
displaying the output of the AV scanner or viewing the log.

Also we found that at least 2 AV scan programs from 2 vendors do not detect
the virus inside and report "clean" instead.

See here for more details:

<ftp://ftp.aerasec.de/pub/advisories/unfiltered-escape-sequences/unfilte
red-escape-sequences.txt>
<http://www.aerasec.de/security/index.html?id=ae-200503-020&lang=en>

We provide also samples and the Perl program for creating the samples:
<ftp://ftp.aerasec.de/pub/advisories/unfiltered-escape-sequences/>

Due lack of time we only tested a few products, so if one can provide
results of other products, pls. send them (also) to us. Thank you!

Regards,
Dr. Peter Bieringer
--
Dr. Peter Bieringer Phone: +49-8102-895190
AERAsec Network Services and Security GmbH Fax: +49-8102-895199
Wagenberger Strasse 1 Mobile: +49-174-9015046
D-85662 Hohenbrunn E-Mail: pbieringer (at) aerasec (dot) de [email concealed]
Germany Internet: http://www.aerasec.de

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