Functional code that demonstrates an exploit of the Microsoft Windows theme file handling arbitrary code execution vulnerability is publicly available.
Microsoft Windows contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system.
The vulnerability is due to improper handling of malicious theme or screen saver files. An unauthenticated, remote attacker could exploit this vulnerability by convincing a targeted user to open a malicious file on an affected system. If successful, the attacker could execute arbitrary code on the system with the privileges of the user.
Functional code that exploits this vulnerability is available as part of the Metasploit framework.
Microsoft has confirmed the vulnerability in a security bulletin and released software updates.
The following Microsoft systems are affected:
Windows XP SP3 and prior
Windows XP Professional x64 Edition SP2 and prior
Windows Server 2003 SP2 and prior
Windows Server 2003 x64 Edition SP2 and prior
Windows Server 2003 with SP2 and prior for Itanium-based Systems
Windows Vista SP2 and prior
Windows Vista x64 Edition SP2 and prior
Windows Server 2008 for 32-bit Systems SP2 and prior
Windows Server 2008 for x64-based Systems SP2 and prior
Windows Server 2008 for Itanium-based Systems SP2 and prior
To exploit the vulnerability, the attacker may provide a file to the user and persuade the user to open or execute the file by using misleading language or instructions. Because theme files are not executable and may be perceived as a safe file type, users may be more likely to open a provided file from an untrusted source.
Microsoft has released a security bulletin at the following link: MS13-071
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code on a targeted system with the privileges of a targeted user. If the user holds elevated privileges, the attacker could completely compromise the system.
The vulnerability is in handling Windows theme configuration files, which allow users to create and save new themes. These theme files could be shared over the Internet by setting a Universal Naming Convention (UNC) path, allowing it to obtain the screen saver .scr file remotely.
An unauthenticated, remote attacker could exploit this vulnerability by convincing a targeted user to open or download a crafted theme file on an affected system. When processed, the screen saver .scr file will be downloaded from a remote location. Successful exploitation could allow an attacker prolonged control of that system because the screen saver would be downloaded each time the user is idle.
Administrators are advised to apply the appropriate updates.
Users are advised not to open email messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in email messages are safe, they are advised not to open them.
Administrators are advised to monitor affected systems.
Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.
Microsoft customers can obtain updates directly by using the links in the security bulletin. These updates are also distributed by Windows automatic update features and available on the Microsoft Update service. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
Version 2, September 17, 2013, 1:40 PM: Additional technical information to describe the Microsoft Windows theme file handling arbitrary code execution vulnerability is available.
Version 1, September 10, 2013, 5:14 PM: Microsoft Windows contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code on a targeted system. Updates are available.
Professional Edition Base, SP1, SP2, SP3 | Professional x64 (AMD/EM64T) Base, SP2
The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.