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Security Advisory: CT12-09-2006-2.htm

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Microsoft Publisher Font Parsing Vulnerability

Advisory Date: 12th, September 2006

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

CVE Reference: CVE-2006-0001

Affected Software

Microsoft Publisher 2000 (Office 2000)
Microsoft Publisher 2002 (Office 2002)
Microsoft Publisher 2003 (Office 2003)

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

Microsoft Publisher is a lightweight desktop publishing (DTP) application bundled
with Microsoft Office Small Business and Professional. The application facilitates
the design of professional business and marketing communications via familiar Office
tools & functionality.

Unfortunately, it transpires that Microsoft Publisher is susceptible to a remote,
arbitrary code execution vulnerability that yields full system access running
in the context of a target user.

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

The vulnerability emanates from Publishers inability to perform sufficient data
validation when processing the contents of a .pub document. As a result, it is
possible to modify a .pub file in such a way that when opened will corrupt critical
system memory, allowing an attacker to execute code of his choice.

More specifically, the vulnerable condition is derived from an attacker controlled
string that facilitates an "extended" memory overwrite using portions of the original
.pub file.

As no checks are made on the length of the data being copied, the net result is
that of a classic "stack overflow" condition, in which EIP control is gained via
one of several return addresses.

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

As with most file orientated vulnerabilities, the aforementioned issue requires
a certain degree of social engineering to achieve successful exploitation.

However, users of Microsoft Publisher 2000 (Office 2000) are at an increased
risk due to the exploitability of the vulnerability in a possible web-based attack
scenario.

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

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

http://www.microsoft.com/technet/security/Bulletin/MS06-054.mspx

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

03/08/2005 Preliminary Vendor notification.
12/08/2005 Vulnerability confirmed by Vendor.
03/01/2006 Public Disclosure Deferred by Vendor.
11/07/2006 Public Disclosure Deferred by Vendor.
12/09/2006 Coordinated public release.

Total Time to Fix: 1 year, 1 month, 6 days (402 days)

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

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

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