Security Update for Microsoft Office to Address Remote Code Execution (MS15-131)

ITS Advisory Number: 
2015-150
Date(s) Issued: 
Tuesday, December 8, 2015
Subject: 
Security Update for Microsoft Office to Address Remote Code Execution (MS15-131)
Overview: 

Multiple vulnerabilities have been discovered in Microsoft Office that could allow remote code execution. Successful exploitation of these vulnerabilities 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.

Systems Affected: 
  • Microsoft Office 2007
  • Microsoft Office 2010
  • Microsoft Office 2013
  • Microsoft Office 2013 RT
  • Microsoft Office 2016
  • Microsoft Office for Mac 2011
  • Microsoft Office for Mac 2016
  • Microsoft Office Compatibility Pack Service Pack 3
  • Microsoft Excel Viewer
RISK
GOVERNMENT
Large and medium government entities: 
High
Small government entities: 
High
BUSINESS
Large and medium business entities: 
High
Small business entities: 
High
Home Users: 
High
Description: 

Multiple vulnerabilities exist in Microsoft Office software when the Office software fails to properly handle objects in memory. Exploitation of these vulnerabilities requires that a user open a specially crafted file with an affected version of Microsoft Office software. Details of them are as follows:

  • Multiple memory corruption vulnerabilities that require a user to open a specially crafted file with an affected version of Microsoft Office: [CVE-2015-6040, CVE-2015-6118, CVE-2015-6122, CVE-2015-6124, CVE-2015-6177]
  • Microsoft Office RCE Vulnerability: [CVE-2015-6172]

Successful exploitation of any of these vulnerabilities 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. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. 

Actions: 
  • After appropriate testing, apply appropriate patches provided by Microsoft to vulnerable systems.
  • Run all software as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack.
  • Remind users not to open files provided by unknown or un-trusted sources.
  • Inform and educate users regarding the threats posed by opening files, especially those from un-trusted sources or suspicious files from trusted sources.