CIS CYBER SECURITY ADVISORIES

MS-ISAC CYBER SECURITY ADVISORY NUMBER:
2011-076

DATE(S) ISSUED:
12/13/2011

SUBJECT:
Vulnerability in Microsoft Office Could Allow For Remote Code Execution (MS11-089)

OVERVIEW:

A vulnerability has been discovered in Microsoft Office, which is Microsoft's business application suite, that could allow attackers to take complete control of affected systems. This vulnerability can be exploited by opening a specially crafted Word file. Successful exploitation could result in an attacker gaining the same privileges as the logged on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Failed exploit attempts will likely cause denial-of-service conditions.
 
SYSTEMS AFFECTED:

  • Microsoft Office for Mac 2011
  • Microsoft Office 2010 32-bit
  • Microsoft Office 2010 64-bit
  • Microsoft Office 2007

 
RISK:
Government:

  • Large and medium government entities: High
  • Small government entities: High

 
Businesses:

  • Large and medium business entities: High
  • Small business entities: High

 
Home users: High
 
DESCRIPTION:
A vulnerability has been identified in Microsoft Office that could allow remote code execution. This vulnerability may be exploited if a user opens a specially crafted Microsoft Word file. Upon parsing the specially crafted Word file, a use-after-free memory error will occur and will result in an attempt to execute arbitrary code.
 
Successful exploitation of this vulnerability could result in the attacker gaining the same rights as the logged on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Failed exploit attempts will likely cause denial-of-service conditions.
 
RECOMMENDATIONS:
We recommend the following actions be taken:

  • Apply appropriate patches provided by Microsoft to vulnerable systems immediately after appropriate testing.
  • Run all software as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack.
  • Do not open email attachments or click on URLs from unknown or untrusted sources.
  • Inform and educate users regarding the threats posed by hypertext links contained in emails, IM (Instant Messages) or attachments especially from un-trusted sources.

 
REFERENCES:
Microsoft:
http://technet.microsoft.com/en-us/security/bulletin/ms11-089/
 
Secunia:
http://secunia.com/advisories/47098/
 
Security Focus:
http://www.securityfocus.com/bid/50956/
 
CVE:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-1983