Microsoft Windows DirectAccess CVE-2013-3876 Security Bypass Vulnerability

Description

Microsoft Windows DirectAccess is prone to a security-bypass vulnerability. An attacker can exploit this issue to bypass certain security restrictions and impersonate a legitimate server to perform man-in-the-middle attacks. Successfully exploiting this issue allows attackers to obtain sensitive information including encrypted domain credentials. Other attacks are also possible.

Technologies Affected

• Microsoft Windows 7 for 32-bit Systems SP1
• Microsoft Windows 7 for x64-based Systems SP1
• Microsoft Windows 8 for 32-bit Systems
• Microsoft Windows 8 for 64-bit Systems
• Microsoft Windows 8.1 for 32-bit Systems
• Microsoft Windows 8.1 for x64-based Systems
• Microsoft Windows RT 8.1
• Microsoft Windows RT
• Microsoft Windows Server 2003 Itanium SP2
• Microsoft Windows Server 2003 SP2
• Microsoft Windows Server 2003 x64 Edition Service Pack 2
• Microsoft Windows Server 2008 R2 for Itanium-based Systems SP1
• Microsoft Windows Server 2008 R2 for x64-based Systems (Server Core instal SP1
• Microsoft Windows Server 2008 R2 for x64-based Systems SP1
• Microsoft Windows Server 2008 for 32-bit Systems (Server Core installation SP2
• Microsoft Windows Server 2008 for 32-bit Systems SP2
• Microsoft Windows Server 2008 for Itanium-based Systems SP2
• Microsoft Windows Server 2008 for x64-based Systems (Server Core installat SP2
• Microsoft Windows Server 2008 for x64-based Systems SP2
• Microsoft Windows Server 2012 (Server Core installation)
• Microsoft Windows Server 2012
• Microsoft Windows Server 2012 R2
• Microsoft Windows Vista SP1
• Microsoft Windows Vista x64 Edition SP2
• Microsoft Windows XP Professional x64 Edition SP2
• Microsoft Windows XP Service Pack 3

Recommendations

Block external access at the network boundary, unless external parties require service.
If global access isn’t needed, filter access to the affected computer at the network boundary. Restricting access to only trusted computers and networks might greatly reduce the likelihood of exploits.

Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of anomalous or suspicious activity. This includes but is not limited to unexplained incoming and outgoing traffic. This may indicate exploit attempts or activity that results from successful exploits.

Do not use client software to communicate with untrusted sources.
To reduce the likelihood of exploits, connect to only trusted hosts and servers.

Updates are available. Please see the references or vendor advisory for more information.