CVE-2002-0117 in YaBB
Summary
by MITRE
Cross-site scripting vulnerability in Yet Another Bulletin Board (YaBB) 1 Gold SP 1 and earlier allows remote attackers to execute arbitrary script and steal cookies via a message containing encoded Javascript in an IMG tag.
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Analysis
by VulDB Data Team • 09/22/2025
The vulnerability identified as CVE-2002-0117 represents a critical cross-site scripting flaw within the Yet Another Bulletin Board version 1 Gold SP 1 and earlier installations. This security weakness resides in the application's handling of user-generated content, specifically when processing messages that contain embedded javascript code within image tags. The vulnerability stems from inadequate input validation and output encoding mechanisms that fail to properly sanitize user-submitted data before rendering it within the web interface. Attackers can exploit this flaw by crafting malicious messages containing encoded javascript within img tags, which then gets executed in the context of other users' browsers when they view the affected content.
This cross-site scripting vulnerability operates under the Common Weakness Enumeration classification of CWE-79, which specifically addresses improper neutralization of input during web page generation. The flaw allows remote attackers to execute arbitrary script code in victims' browsers, effectively bypassing the normal security boundaries that separate user sessions and prevent unauthorized access to sensitive information. The attack vector specifically targets the IMG tag processing functionality within YaBB's message handling system, where the application fails to properly escape or validate javascript code embedded within image attributes. This creates an environment where malicious payloads can be silently executed without user knowledge, potentially leading to session hijacking, credential theft, and other browser-based attacks.
The operational impact of this vulnerability extends beyond simple script execution to encompass significant security risks for forum administrators and users alike. When attackers successfully exploit this flaw, they can steal session cookies, which contain authentication tokens that allow unauthorized access to user accounts. This enables attackers to impersonate legitimate users and perform actions within the bulletin board system that should be restricted to authorized personnel. The vulnerability also facilitates more sophisticated attacks such as defacement of forum content, data exfiltration, and the creation of backdoor access points within the compromised system. Additionally, the persistent nature of forum content means that the malicious scripts can continue to affect users long after the initial attack, creating ongoing security exposure for the entire community.
Mitigation strategies for CVE-2002-0117 should focus on implementing comprehensive input validation and output encoding mechanisms throughout the YaBB application. Organizations should immediately upgrade to patched versions of YaBB that address the specific input sanitization issues within the IMG tag processing functionality. The implementation of proper content security policies and the use of web application firewalls can provide additional layers of protection against similar attacks. Security measures should include the enforcement of strict HTML sanitization rules that prevent javascript execution within user-generated content, particularly within image tags and other HTML elements that may contain dynamic attributes. Regular security auditing and penetration testing of forum systems can help identify similar vulnerabilities that may exist in other components of the application stack. The vulnerability also underscores the importance of maintaining up-to-date security patches and following secure coding practices that prevent the injection of malicious code into web applications, aligning with the ATT&CK framework's approach to defending against web-based exploitation techniques.