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[TZO-23-2009] Avira antivir generic evasion of heuristics (for PDF)
From the low-hanging-fruit-department
Avira Antivir generic PDF evasion of heuristics
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Release mode: Coordinated but limited disclosure.
Ref : [TZO-22-2009] - Avira Antivir generic PDF evasion (heuristics)
WWW : http://blog.zoller.lu/2009/04/advisory-avira-antivir-generic-evasion.html
Vendor : http://www.avira.com
Status : Patched (Engine-Version: AV7 22.214.171.124 / AV8/9: 126.96.36.199)
CVE : none provided
Credit : t.b.a
OSVDB vendor entry: none 
Security notification reaction rating : good
Notification to patch window : 10 days
Disclosure Policy :
Affected products :
- Avira AntiVir Free
- Avira AntiVir Premium
- Avira AntiVir Premium Security Suite
- Avira AntiVir Professional (Desktop)
- Avira AntiVir Server
- Avira AntiVir Exchange
- Avira AntiVir SharePoint
- Avira AntiVir ISA Server
- Avira AntiVir MIMEsweeper
- Avira AntiVir for KEN! 4
- Avira AntiVir Virus Scan Adapter for SAP NetWeaver®
- Avira AntiVir Professional (Unix)
- Avira AntiVir Server (Unix)
- Avira AntiVir MailGate
- Avira AntiVir WebGate
Quote: "Avira AntiVir is a reliable free antivirus solution, that constantly
and rapidly scans your computer for malicious programs such as viruses,
Trojans, backdoor programs, hoaxes, worms, dialers etc. Monitors
every action executed by the user or the operating system and reacts
promptly when a malicious program is detected.
The protection experts have numerous company locations throughout
Germany and cultivate partnerships in Europe, Asia and America.
Avira has more than 180 employees at their main office in Tettnang
near Lake Constance and is one of the largest employers in the region.
AV-Comparatives e.V. have chosen Avira AntiVir Premium as the
best anti-virus solution of 2008"
The heuristics can be bypassed by a special formated PDF "container", this
leads to the bypass of malicious PDF files, old or new. This is not a
bypass that relies on archive structures but relies on evading certain
code paths in the av engine "through various means".
To know more about the impact and type of "evasion", I updated the
description at http://blog.zoller.lu/2009/04/case-for-av-bypassesevasions.html
Interestingly this opens the possibility to evade at scan time and
IV. Disclosure timeline
08/05/2009 : Send proof of concept, description the terms under which
I cooperate and the planned disclosure date.
10/05/2009 : Avira acknowledges receipt.
11/05/2009 : Avira states that the internal development build has been
patched and that the public updates are to be rolled out
end of the week.
18/05/2009 : Avira informs me that "we already released the fixed engine
to the public on friday, 15th May, 17:59 pm CET:
Engine-Version: AV7 188.8.131.52 / AV8/9: 184.108.40.206
18/05/2009 : Release of this advisory.
Avira is encouraged to leave their security contact details at
http://osvdb.org/vendor/1/AVIRA%20GmbH to facilate communication and reduce lost reports.