Microsoft Forefront Unified Access Gateway contains a vulnerability that could allow an unauthenticated, remote attacker to conduct cross-site scripting attacks. Updates are available.
Description
Microsoft Forefront Unified Access Gateway 2010 Update 2 and prior contain a vulnerability that could allow an unauthenticated, remote attacker to conduct cross-site scripting attacks.
The vulnerability is due to errors in processing input supplied to the signurl.asp script via URLs. An unauthenticated, remote attacker could exploit the vulnerability by convincing the user to view a malicious link. If successful, the attacker could conduct a cross-site scripting attack and capture sensitive browser-based information.
Microsoft has confirmed the vulnerability in a security bulletin and released software updates.
Warning Indicators
Microsoft Forefront Unified Access Gateway 2010 Update 2 and prior is vulnerable.
IntelliShield Analysis
To achieve a successful exploit, the attacker must convince a user to follow a malicious link. Attackers may provide links to users in e-mail or instant messages or by posting links on public websites. Attackers may use obfuscation techniques to make malicious URLs more difficult to recognize and may use social engineering techniques to make users more likely to follow a provided link.
The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the November 2010 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 November 2010
Vendor Announcements
Microsoft has released a security bulletin at the following link: MS10-089
Impact
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary script or HTML code in the user's browser in the security context of the targeted site, possibly allowing the attacker to take actions on the site as the user or access sensitive browser-based information.
Technical Information
The vulnerability is due to errors in processing input supplied to the signurl.asp script via URLs. The script fails to properly sanitize supplied input before returning the input to the user.
An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to follow a URL that is designed to submit malicious input to the application. When followed, the URL could direct the user to the vulnerable application and cause the application to return unfiltered input to the user's browser. When rendered in the user's browser, the input could allow the attacker to execute arbitrary script or HTML code in the user's browser in the security context of the affected site.
Safeguards
Administrators are advised to apply the appropriate software updates.
Users are advised not to open e-mail messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in e-mail messages are safe, they are advised not to open them.
Administrators are advised to monitor critical systems.
Patches/Software
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 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
The security vulnerability applies to the following combinations of products.
Primary Products:
Microsoft, Inc.
Forefront Unified Access Gateway
2010 Base, Update 1, Update 2
Associated Products:
N/A
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