Severity: High
12 February, 2008
Summary:
- These vulnerabilities affect: Many current versions of Microsoft Office for Windows (MS08-013 affects OS X, too) and Microsoft Works and Works Suite
- How an attacker exploits them: 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 or Works patches immediately.
Severity: High
12 February, 2008
Summary:
- These vulnerabilities affect: Many current versions of Microsoft Office for Windows (MS08-013 affects OS X, too) and Microsoft Works and Works Suite
- How an attacker exploits them: 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 or Works patches immediately.
Exposure:
Today, Microsoft released four security bulletins describing seven vulnerabilities found in components or programs that ship with Microsoft Office for Windows (and in one case, Office 2004 for Mac). Some of the vulnerabilities also affect Microsoft Works and Works Suite. Each vulnerability affects different versions of Office to a different extent. The seven 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 privilege, the attacker gains full control of the user’s machine. One of the vulnerabilities (MS08-013) allows an attacker to gain complete control of a vulnerable machine immediately.
An attacker can exploit these flaws using just about any Office document. While three of Microsoft’s bulletins specifically mention Word (.doc), Works (.wps) and Publisher (.pub) files, the fourth bulletin only generally mentions, “Office files,” which could refer to any Office document type, including Excel. So beware of all unexpected Office documents.
If you’d like to learn more about each individual flaw, drill into the “Vulnerability Details” section of the security bulletins listed below:
- MS08-009: Word Memory Corruption Vulnerability, rated Critical
- MS08-011: Three Works Vulnerabilities, rated Important
- MS08-012: Two Publisher Vulnerabilities, rated Critical
- MS08-013: Office Remote Code Execution Vulnerability, rated Critical.
In January, Microsoft also released an early advisory warning customers of a zero day vulnerability in Microsoft Excel, which attackers are exploiting in targeted attacks. Surprisingly, Microsoft has not released a security update to patch that zero day Excel vulnerability. Even if you apply all of today’s Office patches, you should still inform your users to remain suspicious of unexpected Excel documents.
Solution Path
Microsoft has released patches for Office and Works to correct all of these vulnerabilities (except for the zero day Excel vulnerability mentioned in the previous paragraph). You should download, test, and deploy the appropriate patches throughout your network immediately.
- Office 2003, Works 8.0, and Works Suite 2005
- Download Microsoft Works 6 File Converter
For All WatchGuard Users:
While you can configure some of WatchGuard’s Firebox models to block all Office documents, most organizations need to allow Office documents in order to conduct business. Blocking them could bring your business to a halt. Therefore, the patches are your best recourse. That said, Microsoft still hasn’t patched one particular zero day Excel vulnerability. You may want to temporarily block .XLS files until Microsoft patches that flaw.
If you want to block any Office documents, follow the links below for instructions on using your Firebox proxies’ content blocking features:
- Firebox X Edge running 8.5
- Firebox III and X Core running WFS
- Firebox X Core and X Peak running Fireware Pro
Status:
Microsoft has released patches correcting these issues.