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Security Advisory: CT12-09-2006

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Adobe/Macromedia Flash Player - Remote Code Execution

Advisory Date: 12th, September 2006

Severity: Critical
Impact: Remote System Access
Solution Status: Vendor Patch

CVE Reference: CVE-2006-3311

Affected Software

Adobe Flash Player 8.0.24.0 and earlier versions
Adobe Flash Professional 8, Flash Basic
Adobe Flash MX 2004
Adobe Flex 1.5

Note: All OS Platforms are vulnerable

1. OVERVIEW
   ===========

Adobe/Macromedia Flash Player is the world's most ubiquitous Browser plug-in
for Microsoft, Mozilla and Apple technologies. The plug-in claims to facilitate
high-impact web interfaces and interactive online advertising for circa 98% of
desktops globally.

Unfortunately, it transpires that Adobe Flash Player is prone to a remote
arbitrary code execution vulnerability, that allows an attacker to gain
control of a target system through the simple invocation of a maliciously
constructed web page.

2. TECHNICAL NARRATIVE
   ======================

The vulnerability originates out of Flash's failure to sufficiently handle
large dynamically generated strings at run time. As a result, it is possible
(using rudimentary Action Script) to create a .swf movie in such a way that
when processed by the Plug-in, will overwrite system memory at an explicit
location.

More specifically, the aforementioned location can (with a certain degree of
accuracy) be attacker controlled via the direct manipulation of the overall
length of the generated string.

The net result is that of a partially controllable condition, which opens the
door to a multitude of differing exploitation vectors, including but not
limited to heap/stack overwrites, and/or 3rd party race conditions.

3. EXPLOITATION
   ===============

Computer Terrorism (UK) can confirm the un-disclosed production of a reliable
multi-platform & multi-browser Web based Proof-Of-Concept (PoC). Such an
exploit could be used in a web-based attack scenario, where unsuspecting
users are lured to a maliciously constructed website.

Users that have not already done so are strongly advised to upgrade to the latest
version of Flash Player or apply the appropriate fix for their particular version.

4. VENDOR RESPONSE
   ==================

The vendor security bulletin and corresponding patches are available at the
following location:

http://www.adobe.com/go/apsb06-11/

5. DISCLOSURE ANALYSIS
   ======================

12/05/2006 Preliminary Vendor notification.
18/05/2006 Vulnerability confirmed in pre-release Flash 9, and earlier versions
28/06/2006 Flash Player 9 released (Fixed)
31/07/2006 Public Disclosure Deferred by Vendor.
12/09/2006 Coordinated public release.

Total Time to Fix: 4 months (123 days)

6. CREDIT
   =========

The vulnerability was discovered by Stuart Pearson of Computer Terrorism (UK) Ltd

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