CVE-2011-1897 in Forefront Unified Access Gateway
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Microsoft Forefront Unified Access Gateway (UAG) 2010 Gold, Update 1, Update 2, and SP1 allows remote attackers to inject arbitrary web script or HTML via unspecified vectors, aka "Default Reflected XSS Vulnerability."
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Analysis
by VulDB Data Team • 11/23/2021
The CVE-2011-1897 vulnerability represents a critical cross-site scripting flaw discovered in Microsoft Forefront Unified Access Gateway 2010 across multiple update versions including Gold, Update 1, Update 2, and Service Pack 1. This vulnerability falls under the CWE-79 category of Cross-Site Scripting and specifically manifests as a reflected XSS attack vector that enables remote threat actors to execute malicious code within the context of affected user sessions. The Unified Access Gateway serves as a critical component in Microsoft's secure access solutions, providing unified authentication and authorization services for enterprise environments while acting as a gateway for remote access to corporate resources.
The technical implementation of this vulnerability stems from inadequate input validation and output encoding mechanisms within the UAG's web interface components. Attackers can exploit this weakness by crafting malicious URLs or form submissions that contain embedded script payloads which are then reflected back to users through the vulnerable application interface. These reflected scripts execute in the victim's browser context, potentially allowing attackers to steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious domains. The unspecified vectors indicate that the vulnerability may exist across multiple input points within the UAG's user interface, making it particularly dangerous as attackers can identify various entry points for exploitation.
The operational impact of CVE-2011-1897 extends beyond simple script injection, as it fundamentally compromises the security posture of organizations relying on Microsoft UAG for remote access control. Successful exploitation could enable attackers to establish persistent access to corporate networks, escalate privileges, or conduct further reconnaissance activities. The vulnerability's remote nature means that attackers need only discover a valid URL containing the malicious payload to compromise user sessions, making it particularly attractive for large-scale attacks. Organizations using UAG for secure remote access would face significant risk of credential theft, data exfiltration, and unauthorized system access, especially in environments where users access sensitive corporate resources through the gateway.
Mitigation strategies for this vulnerability should focus on immediate patch application as Microsoft released security updates to address the reflected XSS flaw in subsequent service packs and updates. Network administrators should implement comprehensive input validation measures including HTML encoding of all user-supplied content, deployment of web application firewalls to detect and block malicious payloads, and regular security assessments of the UAG configuration. The ATT&CK framework categorizes this vulnerability under T1566 - Phishing and T1071.004 - Application Layer Protocol: DNS, highlighting the threat actor techniques that leverage such vulnerabilities for initial access and lateral movement within compromised networks. Additionally, implementing proper security headers including Content Security Policy and X-Content-Type-Options can provide additional defense-in-depth measures against reflected XSS attacks. Organizations should also consider implementing user education programs to recognize suspicious URLs and phishing attempts that might exploit this vulnerability, as social engineering remains a common initial attack vector for XSS exploitation.