CVE-2006-2228 in w-Agora
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in w-Agora (aka Web-Agora) 4.2.0 allows remote attackers to inject arbitrary web script or HTML via a post with a BBCode tag that contains a JavaScript event name followed by whitespace before the = (equals) character, which bypasses a restrictive regular expression that attempts to remove onmouseover and other events.
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Analysis
by VulDB Data Team • 07/25/2018
The vulnerability identified as CVE-2006-2228 represents a critical cross-site scripting flaw within w-Agora version 4.2.0, a web-based discussion forum application that was widely used in enterprise and educational environments during the mid-2000s. This vulnerability resides in the application's input validation mechanisms for BBCode parsing, specifically targeting how the software handles JavaScript event handlers within user-generated content. The flaw demonstrates a classic weakness in security filtering where overly restrictive regular expressions fail to account for various encoding and formatting techniques that attackers can employ to circumvent protection measures.
The technical exploitation of this vulnerability occurs through the manipulation of BBCode tags that contain JavaScript event names such as onclick, onmouseover, or onfocus, followed by whitespace characters before the equals sign. The attackers craft posts containing these malformed BBCode sequences that bypass the regular expression filters designed to strip out dangerous JavaScript events. This bypass mechanism exploits a fundamental flaw in the validation logic where the regular expression fails to properly account for whitespace variations that maintain the structural integrity of the event handler while evading detection. The vulnerability operates at the application layer and requires no authentication from remote attackers, making it particularly dangerous in publicly accessible forum environments where user-generated content is prevalent.
The operational impact of this vulnerability extends beyond simple script execution, as it allows attackers to perform a range of malicious activities including session hijacking, credential theft, and redirection to malicious websites. When users view posts containing the crafted BBCode, their browsers execute the embedded JavaScript code within the context of the vulnerable forum's domain, potentially leading to full compromise of user sessions and access to sensitive information. The vulnerability particularly affects environments where forum administrators do not adequately monitor user-generated content or where the application's security measures are insufficiently configured. This flaw represents a significant risk to organizations relying on web-based collaboration platforms, as it can be exploited to create persistent threats within their network infrastructure.
Security professionals should implement multiple layers of defense to mitigate this vulnerability, beginning with immediate patching of affected w-Agora installations and updating to versions that properly handle BBCode event validation. The mitigation strategy should include enhanced input sanitization that employs more comprehensive regular expressions or alternative validation techniques that account for all possible whitespace variations and encoding methods. Organizations should also consider implementing Content Security Policy headers to limit script execution capabilities and deploy web application firewalls to detect and block suspicious BBCode patterns. This vulnerability aligns with CWE-79, which specifically addresses cross-site scripting vulnerabilities, and maps to ATT&CK technique T1190 for exploitation of web applications. The incident underscores the importance of robust input validation and the dangers of relying solely on regular expression-based filtering for security purposes, particularly in applications that process user-generated content.