CVE-2011-4335 in Contao
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in Contao before 2.10.2 allow remote attackers to inject arbitrary web script or HTML via the PATH_INFO to index.php in a (1) teachers.html or (2) teachers/ action.
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Analysis
by VulDB Data Team • 12/08/2024
The vulnerability identified as CVE-2011-4335 represents a critical cross-site scripting flaw affecting the Contao content management system prior to version 2.10.2. This vulnerability resides in the application's handling of user input through the PATH_INFO parameter when processing requests to specific endpoints including teachers.html and teachers/ actions. The flaw enables remote attackers to execute malicious scripts within the context of a victim's browser session, potentially leading to unauthorized access, data theft, or complete system compromise. The vulnerability specifically targets the index.php file's processing logic, which fails to properly sanitize or validate input parameters derived from the PATH_INFO component of HTTP requests.
The technical nature of this vulnerability aligns with CWE-79, which defines Cross-Site Scripting as a weakness where untrusted data is sent to a web browser without proper validation or encoding. The flaw manifests when the Contao application receives a request containing malicious script code within the PATH_INFO parameter and subsequently incorporates this unvalidated input into dynamically generated web pages. This occurs during the processing of teacher-related content, where the application's input sanitization mechanisms prove insufficient to prevent malicious code execution. Attackers can exploit this by crafting specially formatted URLs that contain script payloads, which then execute when the vulnerable application processes these requests and displays the content to users.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with a foothold for more sophisticated attacks within the target environment. When successful, the XSS payload can steal session cookies, redirect users to malicious sites, modify page content, or perform actions on behalf of authenticated users. The vulnerability affects the teachers.html and teachers/ actions specifically, suggesting that the application's security controls are inconsistent across different content handling paths. This inconsistency creates multiple attack vectors for threat actors, potentially allowing them to escalate privileges or access restricted administrative functions. The remote nature of the attack means that exploitation does not require physical access to the target system, making it particularly dangerous for web applications.
Mitigation strategies for CVE-2011-4335 should prioritize immediate patching of the Contao application to version 2.10.2 or later, which contains the necessary security fixes. Organizations should also implement proper input validation and output encoding mechanisms throughout their web applications, ensuring that all user-supplied data is sanitized before processing. The implementation of Content Security Policy headers can provide additional protection against XSS attacks by restricting the sources from which scripts can be loaded. Security monitoring should be enhanced to detect unusual patterns in PATH_INFO parameter usage, and regular security assessments should be conducted to identify similar vulnerabilities in other components of the web application stack. Network segmentation and access controls can help limit the potential damage if exploitation occurs, while user education about recognizing suspicious web content remains an essential defensive measure. The vulnerability demonstrates the importance of consistent security controls across all application components and highlights the need for comprehensive input validation strategies that align with established security frameworks such as those recommended by OWASP and NIST.