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Credit:
The information has been provided by iDefense.
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Vulnerable Systems:
* Embedded OpenType Font Engine for Windows Vista SP1
* Embedded OpenType Font Engine for Windows XP SP3
During the processing of a malicious OpenType Font, an integer truncation issue can occur on a specific length value. This can result in a large overwrite of the heap using attacker controlled data. The attacker may gain arbitrary execution control by overwriting specific data structures on the heap, such as an object virtual function table.
Exploitation of this vulnerability results in the execution of arbitrary code in the context of the application processing the malicious font file. All applications that support Embedded OpenType Fonts using the T2EMBED library are likely to be vulnerable.
There are several attack vectors available to exploit this vulnerability. A targeted victim may be lured to a website hosting a malicious OpenType font, or the targeted victim may visit a trusted website that been compromised and is hosting a malicious font file. Upon loading the web page, the victim's web browser is compromised. Alternatively, an attacker may email a Microsoft Word document containing a malicious embedded font to the victim. Upon opening the Word document, the victim's Office Word application is compromised.
Patch Availability:
Microsoft has released a patch which addresses this issue. Information about non-directly downloadable vendor updates can be found by clicking on the URLs shown. http://www.microsoft.com/technet/security/bulletin/MS09-029.mspx
Workaround
Internet Explorer provides an option to ignore font styles specified on web pages. Unfortunately this option does not mitigate all aspects of the vulnerability.
On Windows XP the following command may be issued as Administrator to mitigate the vulnerability:
echo y| cacls "%SystemRoot%\system32\t2embed.dll" /E /P everyone:N
On Windows Visa the following commands may be issued as Administrator to mitigate the vulnerability:
takeown.exe /f "%SystemRoot%\system32\t2embed.dll"
echo y| cacls "%SystemRoot%\system32\t2embed.dll" /E /P everyone:N
These commands will prevent the library from being loading into a application. When this command has been issued, Microsoft Internet Explorer and Microsoft Word appear to operate correctly without any serious side effects.
CVE Information:
CVE-2009-0231
Disclosure Timeline:
08/25/2008 - Initial Contact
08/26/2008 - Initial Vendor Response
09/10/2008 - PoC Requested
09/22/2008 - PoC Sent
12/12/2008 - Vendor Status Update - estimated March or May
02/26/2009 - Vendor set tentative release date of 06/09/2009
03/27/2009 - Vendor confirmed attribution.
04/23/2009 - Requested CVE
07/14/2009 - Coordinated Public Disclosure
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