CVE-2009-2371 in Advanced Forum
Summary
by MITRE
Advanced Forum 6.x before 6.x-1.1, a module for Drupal, does not prevent users from modifying user signatures after the associated comment format has been changed to an administrator-controlled input format, which allows remote authenticated users to inject arbitrary web script, HTML, and possibly PHP code via a crafted user signature.
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Analysis
by VulDB Data Team • 02/19/2017
The vulnerability identified as CVE-2009-2371 affects the Advanced Forum module version 6.x before 6.x-1.1 within the Drupal content management system. This represents a critical security flaw that stems from inadequate input validation and access control mechanisms within the module's handling of user-generated content. The vulnerability specifically targets the interaction between user signatures and comment formatting controls, creating an exploitable condition that allows authenticated users to bypass intended security restrictions.
The technical flaw manifests in the module's failure to properly validate user signatures against the current input format settings when those settings are modified by administrators. When an administrator changes the comment format to a restricted input format, the system should prevent users from submitting signatures that could contain malicious code. However, the vulnerability allows users to submit signatures containing arbitrary HTML, JavaScript, and potentially PHP code that remains executable even after the format change. This represents a classic case of insufficient access control and input sanitization, where user input is not properly validated against the current security context.
The operational impact of this vulnerability is significant as it enables remote authenticated users to perform cross-site scripting attacks and potentially achieve code execution on the target system. Attackers can craft malicious signatures that contain scripts designed to steal session cookies, redirect users to malicious sites, or perform other harmful actions. The vulnerability also poses a risk for privilege escalation if the PHP code injection is successful, as it could allow attackers to execute arbitrary commands with the privileges of the web server. This creates a persistent threat vector that remains active until the affected module is updated, potentially affecting all users who have submitted malicious signatures.
Mitigation strategies for this vulnerability primarily focus on immediate remediation through module updates to version 6.x-1.1 or later, which contain the necessary fixes for proper input validation and access control. Organizations should also implement additional security measures including regular security audits of Drupal modules, monitoring for suspicious user activity, and implementing proper input sanitization at multiple layers of the application. The vulnerability aligns with CWE-79 (Cross-site Scripting) and CWE-94 (Code Injection) categories, and represents a technique that could be mapped to ATT&CK tactics such as TA0001 (Initial Access) and TA0002 (Execution) through the exploitation of web application vulnerabilities. System administrators should also consider implementing web application firewalls and content security policies to add additional defense-in-depth measures against similar exploitation vectors.