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Microsoft Security Advisory Notification – Updated Security Advisory (912840)

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Title: Microsoft Security Advisory Notification

Issued: January 3, 2006

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Security Advisories Updated or Released Today ===========

* Security Advisory (912840)

– Title: Vulnerability in Graphics Rendering Engine Could Allow Remote Code Execution.

– Web site:

http://go.microsoft.com/fwlink/?LinkId=58452

– Reason For Update: January 2, 2006: Information has been added to the beginning of the advisory as well as the FAQ section to provide updated

information about the state of the investigation. Information has also been added to the FAQ section regarding reports of a third party security update for this

issue.

From the FAQ:

What is the scope of the advisory?
Microsoft is aware of a new vulnerability report affecting the Graphics Rendering Engine in Microsoft Windows. This vulnerability affects the software that is listed in the “Overview? section.

Is this a security vulnerability that requires Microsoft to issue a security update?
Yes, Microsoft has confirmed this vulnerability and will include the fix for this issue in an upcoming security bulletin.

What causes the vulnerability?
A vulnerability exists in the way specially crafted Windows Metafile (WMF) images are handled that could allow arbitrary code to be executed.

What is the Windows Metafile (WMF) image format?
A Windows Metafile (WMF) image is a 16-bit metafile format that can contain both vector information and bitmap information. It is optimized for the Windows operating system.

For more information about image types and formats, see Microsoft Knowledge Base Article 320314. Additional information about these file formats is also available at the MSDN Library Web site.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take complete control of the affected system. This issue is not known to be wormable. In a Web-based attack scenario, an attacker would host a Web site that exploits this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker’s site. It could also be possible to display specially crafted Web content by using banner advertisements or by using other methods to deliver Web content to affected systems.

How could an attacker exploit the vulnerability?
An attacker could host a malicious Web site that is designed to exploit this vulnerability through Internet Explorer and then persuade a user to view the Web site.

I am reading e-mail in plain text, does this help mitigate the vulnerability?
Yes. Reading e-mail in plain text does mitigate this vulnerability where the e-mail vector is concerned although clicking on a link would still put users at risk.

Note In Windows Server 2003, Microsoft Outlook Express uses plain text for reading and sending messages by default. When replying to an e-mail message that is sent in another format, the response is formatted in plain text.

I have DEP enabled on my system, does this help mitigate the vulnerability?
Software based DEP does not mitigate the vulnerability. However, Hardware based DEP may work when enabled. Please consult with your hardware manufacturer for more information on how to enable this feature and whether it can provide mitigation.

Does this vulnerability affect image formats other than Windows Metafile (WMF)?
The only image format affected is the Windows Metafile (WMF) format. It is possible however that an attacker could rename the file extension of a WMF file to that of a different image format. In this situation, it is likely that the Graphic Rendering engine would detect and render the file as a WMF image which could allow exploitation.

Windows Metafile (WMF) images can be embedded in other files such as Word documents. Am I vulnerable to an attack from this vector?
No. While we are investigating the public postings which seek to utilize specially crafted WMF files through IE, we are looking thoroughly at all instances of WMF handling as part of our investigation. While we’re not aware of any attempts to embed specially crafted WMF files in, for example Microsoft Word documents, our advice is to accept files only from trusted source would apply to any such attempts.

If I block .wmf files by extension, can this protect me against attempts to exploit this vulnerability?
No. Because the Graphics Rendering Engine determines file type by means other than just looking at the file extensions, it is possible for WMF files with changed extensions to still be rendered in a way that could exploit the vulnerability.

Does the workaround in this advisory protect me from attempts to exploit this vulnerability through WMF files with changed extensions?
Yes. Microsoft has tested and can confirm the workaround in this advisory help protect against WMF files with changed extensions.

It has been reported that malicious files indexed by MSN Desktop Search could lead to exploitation of the vulnerability. Is this true?
We have received reports and are investigating them thoroughly as part of our ongoing investigation. We are not aware at this time of issues around the MSN Desktop Indexer, but we are continuing to investigate.

Is this issue related to Microsoft Security Bulletin MS05-053 – Vulnerabilities in Graphics Rendering Engine Could Allow Code Execution (896424) which was released in November?
No, these are different and separate issues.

Will my anti-virus software protect me from exploitation of this vulnerability?
As of the latest update to this advisory the following members of the Virus Information Alliance have indicated that their anti-virus software provides protection from exploitation of Windows Metafile (WMF) files using the vulnerability discussed in this advisory.

Symantec
Computer Associates
McAfee
F-Secure Corporation
Panda Software International
Eset Software
Aladdin
Norman

In addition Microsoft is providing heuristic protection against exploitation of this vulnerability through Windows Metafile (WMF) files in our new Windows OneCare Live Beta.

As currently known attacks can change, the level of protection offered by anti-virus vendors at any time may vary. Customers are advised to contact their preferred anti-virus vendor with any questions they may have or to confirm additional information regarding their vendor’s method of protection against exploitation of this vulnerability.

When this security advisory was issued, had Microsoft received any reports that this vulnerability was being exploited?
Yes. When the security advisory was released, Microsoft had received information that this vulnerability was being actively exploited.

What’s Microsoft’s response to the availability of third party patches for the WMF vulnerability?
Microsoft recommends that customers download and deploy the security update for the WMF vulnerability that we are targeting for release on January 10, 2006.

As a general rule, it is a best practice to utilize security updates for software vulnerabilities from the original vendor of the software. With Microsoft software, Microsoft carefully reviews and tests security updates to ensure that they are of high quality and have been evaluated thoroughly for application compatibility. In addition, Microsoft’s security updates are offered in 23 languages for all affected versions of the software simultaneously.

Microsoft cannot provide similar assurance for independent third party security updates.

Why is it taking Microsoft so long to issue a security update?
Creating security updates that effectively fix vulnerabilities is an extensive process. There are many factors that impact the length of time between the discovery of a vulnerability and the release of a security update. When a potential vulnerability is reported, designated product specific security experts investigate the scope and impact of a threat on the affected product. Once the MSRC knows the extent and the severity of the vulnerability, they work to develop an update for every supported version affected. Once the update is built, it must be tested with the different operating systems and applications it affects, then localized for many markets and languages across the globe.

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January 3, 2006 - Posted by | Antivirus News, Security News

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