CVE-2006-0102 in TinyPHPForum
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in TinyPHPForum (TPF) 3.6 and earlier allows remote attackers to inject arbitrary web script via a javascript: scheme in an "[a]" bbcode tag, possibly the txt parameter to action.php.
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Analysis
by VulDB Data Team • 07/17/2018
The vulnerability identified as CVE-2006-0102 represents a critical cross-site scripting flaw within TinyPHPForum version 3.6 and earlier implementations. This security weakness resides in the forum's handling of user input through bbcode tag processing, specifically when parsing the "[a]" tag that supports javascript: scheme execution. The vulnerability enables remote attackers to inject malicious web scripts directly into the forum's content, potentially compromising user sessions and data integrity. The attack vector exploits the forum's insufficient input validation mechanisms, which fail to properly sanitize or escape user-supplied content before rendering it within the web application's interface.
The technical flaw manifests when the application processes the txt parameter in action.php, which accepts user input containing bbcode tags without adequate sanitization. The "[a]" bbcode tag implementation does not properly validate or filter javascript: schemes, allowing attackers to embed malicious javascript code within forum posts or user profiles. This represents a classic XSS vulnerability that falls under CWE-79, which specifically addresses Cross-Site Scripting flaws in web applications. The vulnerability occurs due to the application's failure to implement proper output encoding or input validation when processing user-generated content, creating an environment where attacker-controlled scripts can execute within the context of other users' browsers.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable sophisticated attacks including session hijacking, credential theft, and redirection to malicious sites. Users who view affected forum content become unwitting participants in the attack, with their browsers executing the injected javascript code. This creates a persistent threat vector that can compromise multiple users simultaneously, as the malicious scripts execute whenever affected content is rendered. The vulnerability's exploitation potential aligns with ATT&CK technique T1566.001, which covers the use of malicious links and scripts in web-based attacks. The impact is particularly severe in forum environments where users trust content from other community members, making the attack surface significantly larger than typical web applications.
Mitigation strategies for this vulnerability require immediate implementation of input validation and output encoding measures. The forum software must be updated to properly sanitize all user input, particularly when processing bbcode tags that allow javascript execution. The recommended approach involves implementing strict input validation that rejects or encodes javascript: schemes within the "[a]" tag processing. Organizations should also implement proper output encoding for all user-generated content, ensuring that any potentially malicious input is rendered harmless before display. Additionally, the application should enforce a content security policy that restricts script execution and prevents unauthorized code injection. The vulnerability demonstrates the critical importance of input validation and output encoding in web applications, as outlined in OWASP Top Ten security principles. Upgrading to a patched version of TinyPHPForum or implementing custom sanitization filters represents the most effective remediation approach to prevent exploitation of this XSS vulnerability.