CVE-2011-4951 in EGroupware Enterprise Line
Summary
by MITRE
Open redirect vulnerability in phpgwapi/ntlm/index.php in EGroupware Enterprise Line (EPL) before 11.1.20110804-1 and EGroupware Community Edition before 1.8.001.20110805 allows remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via a URL in the forward parameter.
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Analysis
by VulDB Data Team • 12/12/2021
The CVE-2011-4951 vulnerability represents a critical open redirect flaw discovered in the EGroupware Enterprise Line and Community Edition platforms, specifically within the phpgwapi/ntlm/index.php component. This vulnerability enables remote attackers to manipulate user redirection behavior by exploiting a forward parameter that controls where users are directed after authentication. The issue affects versions prior to 11.1.20110804-1 for Enterprise Line and 1.8.001.20110805 for Community Edition, making it a significant concern for organizations relying on these platforms for business communication and collaboration.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the authentication flow of EGroupware. When users attempt to access protected resources, the system processes a forward parameter that is intended to redirect users to their requested destination after successful authentication. However, the application fails to properly validate or sanitize this parameter, allowing attackers to inject malicious URLs that will be executed during the redirect process. This flaw directly violates the principle of secure input handling and demonstrates poor security practices in parameter validation. The vulnerability aligns with CWE-601 Open Redirect vulnerability classification, which specifically addresses situations where applications redirect users to unvalidated external URLs, potentially leading to phishing attacks and user deception.
The operational impact of this vulnerability extends beyond simple redirection, creating significant risks for organizations using EGroupware platforms. Attackers can craft malicious links that appear legitimate but redirect users to phishing sites designed to capture credentials or sensitive information. This capability enables sophisticated social engineering campaigns where users might be tricked into believing they are accessing authorized corporate resources while actually being directed to attacker-controlled domains. The vulnerability undermines user trust in the platform and creates potential entry points for more serious attacks, as compromised credentials could provide access to broader network resources. Organizations may experience reputational damage and regulatory compliance issues if user data is compromised through such redirects.
Mitigation strategies for CVE-2011-4951 should focus on immediate patching of affected EGroupware versions to the secure releases mentioned in the vulnerability description. Organizations should implement comprehensive input validation mechanisms that verify the forward parameter against a whitelist of approved domains or implement strict URL validation that ensures redirects only occur to internal resources. Network-level controls such as web application firewalls can provide additional protection by monitoring and blocking suspicious redirect patterns. Security teams should also conduct thorough audits of authentication flows to identify similar vulnerabilities in other components of the EGroupware platform. From an ATT&CK framework perspective, this vulnerability maps to T1566 Phishing and T1071.004 Application Layer Protocol: Web Protocols, highlighting the need for defensive measures against credential theft through deceptive redirect mechanisms. Regular security assessments and penetration testing should be implemented to identify and remediate similar vulnerabilities across the organization's technology stack.