CVE-2020-15516 in mm_forum Extension
Summary
by MITRE
The mm_forum extension through 1.9.5 for TYPO3 allows XSS that can be exploited via CSRF.
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Analysis
by VulDB Data Team • 10/29/2020
The vulnerability identified as CVE-2020-15516 affects the mm_forum extension version 1.9.5 and earlier in the TYPO3 content management system, representing a critical security flaw that combines cross-site scripting with cross-site request forgery exploitation vectors. This vulnerability resides within the forum extension's handling of user input and request processing mechanisms, creating a dangerous combination that allows attackers to execute malicious scripts in the context of authenticated users' browsers. The issue stems from insufficient validation and sanitization of user-provided data within the extension's form handling and submission processes, particularly when processing forum-related content and user interactions. The vulnerability is particularly concerning because it leverages the inherent trust relationship between the user's browser and the TYPO3 application, enabling attackers to craft malicious payloads that can be executed when authenticated users interact with compromised forum content.
The technical implementation of this vulnerability involves the mm_forum extension's failure to properly sanitize input parameters when processing user submissions, particularly within forum post creation, editing, and reply functionalities. When a user submits content through the forum interface, the extension does not adequately validate or escape special characters in the submitted data, allowing malicious script code to be stored and subsequently executed when other users view the content. The CSRF component of this vulnerability means that attackers can craft malicious requests that exploit the user's authenticated session to perform actions without their knowledge, making the attack more stealthy and effective. The vulnerability specifically targets the extension's parameter handling within the TYPO3 framework's request processing pipeline, where user input flows directly into output rendering without proper security filtering mechanisms. This flaw aligns with CWE-79, which describes cross-site scripting vulnerabilities, and CWE-352, which addresses cross-site request forgery issues, demonstrating how multiple security weaknesses can compound to create more severe threats.
The operational impact of CVE-2020-15516 extends beyond simple script execution, potentially enabling attackers to hijack user sessions, steal sensitive information, modify forum content, and even propagate malicious code throughout the affected TYPO3 installation. An attacker could exploit this vulnerability to inject malicious JavaScript that could steal cookies, redirect users to phishing sites, or perform administrative actions on behalf of authenticated users. The implications for organizations using TYPO3 with the mm_forum extension are significant, as compromised forums can serve as entry points for broader attacks against the entire web application infrastructure. The vulnerability affects not just individual forum posts but also the broader user experience, potentially corrupting forum data and undermining user trust in the platform. Organizations may face reputational damage, regulatory compliance issues, and potential data breaches if this vulnerability is exploited in production environments.
Mitigation strategies for CVE-2020-15516 require immediate action including updating the mm_forum extension to version 1.9.6 or later, which contains the necessary security patches to address both the XSS and CSRF vulnerabilities. System administrators should also implement proper input validation and output encoding mechanisms at multiple layers of the application, ensuring that all user-provided content is sanitized before storage and rendering. The implementation of Content Security Policy headers can provide additional defense-in-depth measures against XSS exploitation, while proper CSRF token validation should be enforced for all state-changing operations within the forum extension. Organizations should conduct thorough security assessments of their TYPO3 installations to identify other potentially vulnerable extensions and ensure that all third-party components are kept current with security patches. The ATT&CK framework categorizes this vulnerability under techniques related to code injection and credential access, emphasizing the need for comprehensive security monitoring and incident response procedures to detect and respond to exploitation attempts. Regular security audits and penetration testing should be implemented to identify similar vulnerabilities in other extensions and the core TYPO3 framework itself, ensuring that the entire application stack maintains adequate security posture against evolving threats.