CVE-2010-2796 in phpCAS
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in phpCAS before 1.1.2, when proxy mode is enabled, allows remote attackers to inject arbitrary web script or HTML via a callback URL.
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Analysis
by VulDB Data Team • 09/21/2021
The CVE-2010-2796 vulnerability represents a critical cross-site scripting flaw in the phpCAS library version 1.1.1 and earlier, specifically when operating in proxy mode. This vulnerability stems from insufficient input validation and sanitization of callback URLs, creating an avenue for malicious actors to execute arbitrary web scripts or HTML code within the context of authenticated users' browsers. The phpCAS library serves as a client-side implementation of the Central Authentication Service protocol, facilitating single sign-on capabilities across web applications, making this vulnerability particularly dangerous in enterprise environments where centralized authentication is prevalent.
The technical exploitation of this vulnerability occurs through the proxy mode functionality of phpCAS, which enables applications to act as proxies for authentication requests. When attackers craft malicious callback URLs containing script tags or HTML content, the vulnerable library fails to properly sanitize these inputs before processing them. This flaw directly maps to CWE-79, which defines Cross-Site Scripting as a weakness where untrusted data is incorporated into web pages without proper validation or escaping mechanisms. The vulnerability is particularly insidious because it leverages the legitimate authentication flow of phpCAS, making it difficult for security monitoring systems to distinguish between benign and malicious requests.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform session hijacking, steal authentication tokens, or redirect users to malicious sites. In environments where phpCAS is deployed for enterprise single sign-on, an attacker could potentially compromise user sessions across multiple applications that rely on the same authentication infrastructure. The vulnerability affects not just individual web applications but the entire authentication ecosystem, as compromised sessions could lead to unauthorized access to sensitive corporate data, privileged system access, or lateral movement within network perimeters. This represents a significant threat to the confidentiality and integrity of authentication processes, potentially undermining the security posture of organizations relying on centralized authentication services.
Organizations should immediately upgrade to phpCAS version 1.1.2 or later, which includes proper input sanitization and validation for callback URLs. Additional mitigations include implementing Content Security Policy headers to restrict script execution, monitoring for unusual callback URL patterns, and conducting security reviews of all authentication-related code. The vulnerability aligns with ATT&CK technique T1566, which covers social engineering through malicious links, and T1071, covering application layer protocol usage. Network administrators should also consider implementing web application firewalls to detect and block suspicious callback URL patterns, while security teams should monitor for indicators of compromise related to authentication flows and session management anomalies.