Vendor: FRISK (F-Prot), http://www.f-prot.com
Affected Products: F-Prot Anti-Virus all platforms
Vulnerability: Out-of-Bound Memory Access DoS (remote)
2008/01/22 initial notification to FRISK
2008/01/22 FRISK Response
2008/01/22 PGP public keys exchange
2008/01/23 n.runs has problems importing FRISK's provided public
key, so proceed to search on the key servers and import
the available ones and informs FRISK about it
2008/01/23 FRISK replies that the keys on the key server are fine to
2008/01/23 PoC files sent to FRISK
2008/01/26 FRISK acknowledges the PoC files and informs about having
some problem reproducing them and requests exact version
and configuration used to trigger the vulnerability
2008/01/28 FRISK communicates to n.runs that they were able to
reproduce one of the issues that they had just fixed
and that the update will be included in the upcoming
2008/01/28 n.runs thanks FRISK for such a quick response, provides
the exact version used while bug hunting and informs that
the issues were found about a year before; the reason of
the late report is because it was overseen until now.
2008/01/29 FRISK replies that the version used in the test is quite
old (4.3.1 against actual 4.4.3) and that during that
time many bugs had been fixed
2008/03/16 n.runs realizes that FRISK has released the update
because of a post on 27.Feb.2008 at the following link:
n.runs decides to not launch the advisory because
couldn't find an official post.
2008/07/10 n.runs finds the official announcement:
2008/07/16 n.runs releases this advisory
FRISK Software International, established in 1993, is one of the world's
leading companies in antivirus research and product development.
FRISK Software produces the hugely popular F-Prot Antivirus product range
offering unrivalled heuristic detection capabilities. In addition to this,
the F-Prot AVES managed online e-mail security service filters away the
nuisance of spam e-mail as well as viruses, worms and other malware that
increasingly clog up inboxes and threaten data security.
By supporting a wide range of platforms FRISK Software protects computer
networks of all sizes, running on diverse platforms. As a result, FRISK
Software provides its customers with comprehensive computer security
A remotely exploitable vulnerability has been found in the files'
In detail, the following flaw was determined:
- DoS caused by an Out-of-Bound Memory Access while parsing CHM file's
header: if the nb_dir field (Chunk number of root index chunk) value is set
to 0xffffffff pointers math takes place and ends up in an out-of-bound read
This problem can lead to remote denial of service if an attacker
carefully crafts a file that exploits the aforementioned vulnerability.
The vulnerability is present in FRISK Anti-virus software mentioned
above, in all platforms supported by the affected products prior to the
engine Version 4.4.4.
The vulnerability was reported on 22.Jan.2008 and the engine 4.4.4 has
been issued to solve this vulnerability. For detailed information about
the fixes follow the link in References  section of this document.
n.runs AG wants to highlight the excellent and fluent communication
with FRISK and its very quick response to validate and fix the issue.
Bugs found by Sergio Alvarez of n.runs AG.
This Advisory and Upcoming Advisories:
Unaltered electronic reproduction of this advisory is permitted. For all
other reproduction or publication, in printing or otherwise, contact
email@example.com for permission. Use of the advisory constitutes
acceptance for use in an "as is" condition. All warranties are excluded.
In no event shall n.runs be liable for any damages whatsoever including
direct, indirect, incidental, consequential loss of business profits or
special damages, even if n.runs has been advised of the possibility of