Office Update Fixes Flaws with Image Embedded Documents

Summary:

• These vulnerabilities affect: All current versions of Microsoft Office for Windows, as well as Works 9
• How an attacker exploits them: Typically, by enticing you to open maliciously crafted Office documents
• Impact: An attacker can execute code, potentially gaining complete control of your computer
• What to do: Install the appropriate Office patches immediately, or let Windows Update do it for you.

Exposure:

Today, Microsoft released two security bulletins describing twelve vulnerabilities found in components or programs that ship with Microsoft Office for Windows — more specifically, Publisher and the Office Graphics Filters component. Some of the vulnerabilities also affect the Office Converter Pack, Microsoft Works 9.

The twelve flaws affect different components and applications within Office, but the end result is always the same. By enticing one of your users into downloading and opening a maliciously crafted Office document, an attacker can exploit any of these vulnerabilities to execute code on a victim’s computer, usually inheriting that user’s level of privileges and permissions. If your user has local administrative privileges, the attacker gains full control of the user’s machine.

Since many of the vulnerabilities have to do with an attacker embedding specially crafted image files within any Office document, all types of Office documents could trigger these flaws. Warn your users to beware of all unexpected Office documents they receive.

If you’d like to learn more about each individual flaw, drill into the “Vulnerability Details” section of the security bulletins listed below:

• MS10-103: Multiple Publisher Code Execution Vulnerabilities, rated Important
• MS10-105: Multiple Office Graphics Filters Code Execution Vulnerabilities, rated Important

Solution Path

Microsoft has released patches for Office to correct all of these vulnerabilities. You should download, test, and deploy the appropriate patches throughout your network immediately.

MS10-103:

• Office Publisher 2002
• Office Publisher 2003
• Office Publisher 2007
• Office Publisher 2010
• Office Publisher 2010 x64
  

MS10-105:

• Office XP w/SP3
• Office 2003 w/SP3
• 2007 Microsoft Office System w/SP2
• Office 2010
• Office 2010 x64
• Office Converter Pack
• Works 9
  

For All WatchGuard Users:

While you can configure certain WatchGuard Firebox models to block Microsoft Office documents, most organizations need to allow them in order to conduct business. Furthermore, you’d have to block all types of Office documents in order to mitigate the risk posed by one of these vulnerabilities. Therefore, the patches above are your best recourse.

Nonetheless, if you want to block all Office documents, the links below contain video instructions showing how your Fireboxes proxy policies can block files by extension. Keep in mind, this technique also blocks legitimate documents as well.

• Firebox X Edge running 10.x
  • How do I block files with the FTP proxy?
  • How do I block files with the HTTP proxy?
  • How do I block files with the POP3 proxy?
  • How do I block files with the SMTP proxy
• Firebox X Core and X Peak running Fireware 10.x or Fireware XTM
  • How do I block files with the FTP proxy?
  • How do I block files with the HTTP proxy?
  • How do I block files with the POP3 proxy?
  • How do I block files with the SMTP proxy?

Status:

Microsoft has released Office updates to fix these vulnerabilities.

References:

• MS Security Bulletin MS10-103
• MS Security Bulletin MS10-105

This alert was researched and written by Corey Nachreiner, CISSP.