CVE-2002-0474 in Zeroforum
Summary
by MITRE
Cross-site scripting vulnerability in ZeroForum allows remote attackers to execute arbitrary Javascript on web clients by embedding the script within IMG image tag.
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Analysis
by VulDB Data Team • 06/19/2024
The vulnerability described in CVE-2002-0474 represents a classic cross-site scripting flaw within the ZeroForum web application, which operates under the broader category of web application security weaknesses. This particular vulnerability exists in the processing of user input within the forum's image handling functionality, specifically when processing image tags that contain embedded script code. The flaw allows malicious actors to inject malicious javascript code into the forum's image rendering mechanism, creating a persistent vector for client-side exploitation. The vulnerability is particularly concerning because it leverages the widely trusted IMG tag, which is commonly used in web pages and typically does not trigger security warnings in web browsers, making the attack more subtle and effective.
The technical mechanism of this vulnerability stems from insufficient input validation and output encoding within the ZeroForum application's image processing pipeline. When users submit content containing image tags with embedded javascript code, the application fails to properly sanitize or escape the input before rendering it in the web interface. This occurs because the forum application does not adequately filter the attributes of the IMG tag, particularly the src attribute or other potentially dangerous parameters that could contain malicious payloads. The vulnerability manifests when the web application displays user-generated content without proper sanitization, allowing the embedded javascript code to execute within the context of the victim's browser session. This represents a direct violation of secure coding practices and falls under the CWE-79 category of Cross-Site Scripting, specifically categorized as a reflected XSS vulnerability where the malicious script is stored and then executed by the web application.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with a means to compromise user sessions, steal sensitive information, and potentially escalate privileges within the forum environment. Attackers can leverage this vulnerability to steal cookies, session tokens, or other sensitive data from authenticated users, effectively enabling session hijacking attacks. The vulnerability also allows for more sophisticated attacks such as redirecting users to malicious sites, defacing the forum content, or even creating backdoor access points within the compromised user's browser. From an attacker's perspective, this vulnerability is particularly attractive because it requires minimal technical expertise to exploit and can affect multiple users simultaneously. The attack vector is relatively simple to implement since it only requires embedding malicious javascript within an IMG tag, which is a standard web element that users expect to be safe. This vulnerability also aligns with the ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript, as it enables the execution of malicious javascript code in the victim's browser environment.
Mitigation strategies for this vulnerability require immediate implementation of proper input validation and output encoding mechanisms within the ZeroForum application. The primary defense involves sanitizing all user input that will be rendered in web pages, particularly focusing on image tags and their attributes. Implementing a comprehensive content security policy that restricts script execution and properly encoding all dynamic content can effectively prevent this class of attack. Additionally, the application should employ proper HTML escaping techniques when rendering user-generated content, ensuring that any potentially dangerous characters are properly encoded before display. The system should also implement a whitelist approach for allowed image sources and attributes, rejecting any input that contains suspicious patterns or embedded script code. From a defensive standpoint, network-based intrusion detection systems should be configured to monitor for suspicious image tag patterns, and regular security audits should be conducted to identify similar vulnerabilities in other components of the web application. The vulnerability also highlights the importance of following secure coding guidelines and implementing proper input validation at multiple layers of the application architecture to prevent similar issues from occurring in other parts of the system.