Vulnerabilities in Microsoft Excel Could Allow Remote Code Execution(MS13 -073)

ITS Advisory Number: 
2013-084
Date(s) Issued: 
Tuesday, September 10, 2013
Subject: 
Vulnerabilities in Microsoft Excel Could Allow Remote Code Execution(MS13 -073)
Overview: 

Multiple vulnerabilities have been discovered in Microsoft Office Excel, a spreadsheet application. These vulnerabilities could allow remote code execution if a user opens a specially crafted Excel file. The file may be received as an email attachment, or downloaded via the web. 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.

Systems Affected: 
  • Microsoft Office 2003
  • Microsoft Office 2007
  • Microsoft Office 2010
  • Microsoft Office 2013
  • Microsoft Office 2013 RT
  • Microsoft Office 2004 for Mac
  • Microsoft Office 2008 for Mac
  • Microsoft Office 2011 for Mac
  • Open XML File Format Converter for Mac
  • Microsoft Excel Viewer
  • Microsoft Office Compatibility Pack
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: 

Three vulnerabilities have been identified in Microsoft Office Excel that could allow an attacker to take complete control of an affected system. Details of these vulnerabilities are as follows:

Two Memory Corruption Vulnerabilities (CVE-2013-1315, CVE-2013-3158) are caused by the way that Microsoft Excel parses content in Excel files. Attackers could exploit these two vulnerabilities to gain the same rights as the current user. Attackers that successfully exploit this vulnerability could take complete control over the affected system. The attackers could then install programs; view, change, or delete data; or create new accounts with full user rights.

A third vulnerability (XML External Entities Resolution CVE-2013-3159) is caused by the way that Microsoft Excel parses specially crafted XML files containing external entities. Successful exploitation of this vulnerability could allow attackers to read data from files located on the targeted system. The above vulnerabilities can be exploited by opening specially crafted Excel files received as email attachments, or by visiting websites that host specially crafted Excel documents.

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.

Actions: 
  • 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.
  • Remind users not to download or open files from un-trusted websites.
  • Remind users not to open email attachments from unknown or untrusted sources.
References: 
Microsoft:
http://technet.microsoft.com/en-us/security/bulletin/ms13-073
CVE:
http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-1315
http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-3158
http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-3159