Additional information is available for the Microsoft Windows HTTP services user account credentials reflection vulnerability.
Description
Microsoft Windows contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
This vulnerability exists due to insufficient credential protections when transmitting NTLM credentials to remote websites. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to visit a malicious website. If successful, the attacker could execute arbitrary code with the privileges of the user.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates that correct it.
Warning Indicators
The following applications and systems utilize the vulnerable components:
Internet Explorer 5.01 SP4 and prior
Internet Explorer 6 SP1 and prior
Internet Explorer 7 and prior
Windows 2000 SP4 and prior
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 for Itanium-based Systems with SP2 and prior
Windows Vista SP1 and prior
Windows Vista x64 Edition SP1 and prior
Windows Server 2008 for 32-bit Systems
Windows Server 2008 for x64-based Systems
Windows Server 2008 for Itanium-based Systems
IntelliShield Analysis
An attacker cannot directly exploit this vulnerability, and instead must rely upon user interaction in order to exploit the vulnerability. An attacker must convince a user to view a malicious website. If successful, the attacker could capture user NTLM credentials and reuse those credentials to take actions on the user's system. If the user holds Administrator privileges, the attacker could take complete control over the system.
WinHTTP is an API for servers and services on Windows systems, and is used to make HTTP requests in scenarios that do not require user interaction. It is used in some Windows features such as Universal Plug and Play (UPnP). Interactive client applications typically use the WinINet API, while Microsoft recommends that .Net programs utilize the System.net classes.
Exploitation is only possible from the Intranet zone, and not the Internet zone, and only against systems that accept inbound SMB traffic. Therefore, in order to exploit this vulnerability, an attacker must have access to a system that is on the same internal network as a targeted system that accepts such traffic. If the attacker is on an internal system, incoming SMB traffic may be permitted. However, most corporate firewalls will be configured so as not to allow incoming SMB traffic.
Systems joined to a Windows Active Directory domain may be at greater risk of exploitation. Windows XP client systems not joined to a domain use the Guest account to process network logons, preventing user credentials from passing over the network. However, client systems joined to a domain will use user credentials as part of network logons, exposing them to a reflection attack.
The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the April 2009 security bulletin release. This Cisco bulletin, which assists administrators in identifying or mitigating these vulnerabilities using Cisco devices, is available at the following link: Cisco Applied Mitigation Bulletin: Microsoft Security Bulletin Release for April 2009
The update available from Microsoft corrects this vulnerability by performing proper credential reply validation.
Vendor Announcements
Microsoft has released security bulletins at the following links: MS09-013 and MS09-014
Impact
An unauthenticated, remote attacker could exploit this vulnerability to replay user account credentials, allowing the attacker to take actions on the system with the privileges of the user.
Technical Information
This vulnerability exists due to insufficient credential protections when transmitting NTLM credentials to remote websites. The Windows HTTP Services (WinHTTP) and WinINET APIs fail to protect NTLM credentials against reflection attacks. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to visit a malicious website. The attacker could capture and replay credentials back to the user's system, allowing the attacker to take actions on the system with the privileges of the user.
Safeguards
Administrators are advised to apply the available software updates.
Users are advised not to follow unsolicited links. Users should verify the authenticity of unexpected links prior to following them.
Administrators are advised to run applications and services with the least necessary privileges.
Administrators are advised to monitor critical systems for signs of exploitation.
Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.
Patches/Software
Microsoft customers can obtain updates directly by using the links in the MS09-013 and MS09-014 security bulletins. These updates are also distributed by Windows automatic update features and available on the Windows Update website. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
Signatures
Cisco Systems Cisco Intrusion Prevention System (IPS) 6.0
Version 1, April 14, 2009, 2:38 PM: Microsoft Windows contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code with the privileges of the user. Updates are available.
Datacenter Edition Base | Datacenter Edition, 64-bit Base | Enterprise Edition Base | Enterprise Edition, 64-bit Base | Essential Business Server Premium Base | Essential Business Server Premium, 64-bit Base | Essential Business Server Standard Base | Itanium-Based Systems Edition Base | Standard Edition Base | Standard Edition, 64-bit Base | Web Server Base | Web Server, 64-bit Base
Microsoft, Inc.
Windows Vista
Business Base, SP1 | Business x64 Edition Base, SP1 | Enterprise Base, SP1 | Enterprise x64 Edition Base, SP1 | Home Basic Base, SP1 | Home Basic x64 Edition Base, SP1 | Home Premium Base, SP1 | Home Premium x64 Edition Base, SP1 | Ultimate Base, SP1 | Ultimate x64 Edition Base, SP1
Microsoft, Inc.
Windows XP
Home Edition Base, SP1, SP2, SP3 | Professional Edition Base, SP1, SP2, SP3 | Professional x64 (AMD/EM64T) Base
Associated Products:
N/A
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