Microsoft Forefront Unified Access Gateway contains a vulnerability that could allow an unauthenticated, remote attacker to conduct spoofing attacks. Updates are available.
Description
Microsoft Forefront Unified Access Gateway 2010 Update 2 and prior contains a vulnerability that could allow an unauthenticated, remote attacker to conduct spoofing attacks.
The vulnerability exists due to improper validation of 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 spoofing attack that could allow the attacker to capture user authentication credentials.
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 exploit this vulnerability, the attacker would have to convince the user to view a malicious website. The attacker may provide links to the user within e-mail or instant messages, along with content instructing the user to follow the provided link. In most spoofing exploits, the attacker also depends on the user to further interact with the malicious website by entering sensitive information. If successful, the attacker could capture user credentials for use in further exploits.
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 redirect users from the application to a third-party website without the user's knowledge, possibly aiding the attacker in spoofing attempts.
Technical Information
The vulnerability exists due to improper validation of URLs that redirect users from the Forefront Unified Access Gateway (UAG) to third-party sites.
An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to follow a malicious URL. The URL could be constructed in such a way that the user would first access the UAG interface and then redirect to a third-party website without the user's knowledge, assisting in a spoofing attack.
To expand upon the exploit, the attacker could construct the untrusted website in such a way to mimic the UAG interface, prompting the user to enter credentials normally used to log in to the UAG application. If successful, the spoofing attack could allow the attacker to capture a user's authentication credentials.
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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