bzip2 bombs still causes problems in antivirus-software

["Dr. Peter Bieringer" <pbieringer () aerasec de>]

Hi,

sure you remember the e-mail from Steve Wray in August 2003 about bzip2 
bombs and the possible DoS against antivirus-software:
http://lists.netsys.com/pipermail/full-disclosure/2003-August/009255.html

We found that this is still an issue, especially we found that one vendor 
detects bzip2 bombs by pattern (2 GB of zeros are detected, but not 2 GB of 
e.g. 0x31).

Also others will neither detect the bomb, nor stopping decompression, looks 
like they missing smart code for anomaly detection and/or proper limits and 
eat all existing disk space and CPU power instead of reporting a problem.


Namely we confirm this issue still exists on:

* kavscanner of
  Kaspersky AntiVirus for Linux 5.0.1.0 (probably all versions since 4.5)
* vscan of
  Trend Micro InterScan VirusWall 3.8 Build 1130
* uvscan of
  McAfee Virus Scan for Linux v4.16.0


Probably other versions and products are vulnerable, too.


Full advisory is available here:

http://www.aerasec.de/security/advisories/txt/bzip2bomb-antivirusengines.txt


Hope this helps to bring this issue up again on software vendors to 
implement more smarter anomaly detection code and configurable limits 
(number of files, max size) in the decompression unit.


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 () aerasec de
Germany                                Internet: http://www.aerasec.de