n.runs AG             
http://www.nruns.com/                     security(at)nruns.com
n.runs-SA-2007.009                                           25-May-2007
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Vendor:             ALWIL Software a.s., http://www.avast.com
Affected Product:      avast! antivirus
Vulnerability:         Arbitrary Code Execution (remote) 
Risk:                  HIGH
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Vendor communication:

  2007/05/07    initial notification to ALWIL Software a.s.
  2007/05/07    ALWIL Software a.s. Response
  2007/05/07    PoC files sent to ALWIL Software a.s.
  2007/05/09    ALWIL Software a.s. Response
  2007/05/09    resent PoC files sent to ALWIL Software a.s.
  2007/05/09    ALWIL Software a.s. acknowledge the PoC files
  2007/05/10    ALWIL Software a.s. issued the fix for testing
  2007/05/16    ALWIL Software a.s. released Update with fixes
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Overview:
 
The company specializes in security software, with avast! antivirus being
the flagship product line. During the lifetime of the product line, avast!
products have become both award winning, and number one in a number of key
markets, as well as increasing market share year-on-year since first
international release.
On 11th May 2007 avastR! antivirus Home Edition reached 30 million
registered users.

Description:

A remotely exploitable vulnerability has been found in the file parsing
engine.

In detail, the following flaw was determined:

- Heap Overflow through Integer Cast Around in .SIS file parsing


Impact:

This problem can lead to remote arbitrary code execution if an attacker
carefully crafts a file that exploits the aforementioned vulnerability. The
vulnerability is present in avast! Antivirus software versions prior to the
update Version 4.7.700. 

Solution: 
The vulnerability was reported on 07.May.2007 and an update has been issued
on 16.May.2007 to solve this vulnerability through the regular update
mechanism.
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Credit: 
Bugs found by Sergio Alvarez of n.runs AG. 
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References: 
http://www.avast.com/eng/adnm-management-client-revision-history.html
http://www.avast.com/eng/search.php?searchFor=sergio+alvarez

This Advisory and Upcoming Advisories:
http://www.nruns.com/security_advisory.php
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