CVE-2012-3844 in vBulletin
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in vBulletin 4.1.12 allows remote attackers to inject arbitrary web script or HTML via a long string in the subject parameter when creating a post.
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Analysis
by VulDB Data Team • 02/18/2019
The vulnerability identified as CVE-2012-3844 represents a critical cross-site scripting flaw within the vBulletin forum software version 4.1.12. This security weakness resides in the forum's handling of user input during post creation processes, specifically when processing the subject parameter of forum posts. The flaw enables malicious actors to execute arbitrary web scripts or HTML code within the context of other users' browsers, potentially compromising the entire user base of the affected forum system. The vulnerability stems from inadequate input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before it is rendered back to end users. This particular version of vBulletin was widely deployed across numerous websites, making the impact of this vulnerability significant and far-reaching.
The technical exploitation of this XSS vulnerability occurs when an attacker crafts a malicious string that exceeds normal input length limits and submits it within the subject field of a new forum post. The vulnerability is classified as a reflected XSS attack because the malicious content is immediately reflected back to users who view the affected post without any server-side storage of the malicious payload. The flaw exists due to insufficient sanitization of the subject parameter, allowing HTML and JavaScript code to pass through the input validation mechanisms unimpeded. According to CWE-79, this vulnerability falls under the category of Cross-Site Scripting, which is a common weakness in web applications where user-controllable data is not properly escaped or filtered before being rendered in web pages. The attack vector is particularly dangerous because forum subjects are typically displayed prominently in user interfaces, making them prime targets for XSS exploitation.
The operational impact of CVE-2012-3844 extends beyond simple script execution, as it can enable sophisticated attack chains that compromise user sessions and facilitate further exploitation. Attackers can leverage this vulnerability to steal session cookies, redirect users to malicious websites, deface forum content, or inject phishing pages that appear legitimate to forum users. The vulnerability also creates opportunities for privilege escalation attacks where authenticated users might be tricked into executing malicious code that could compromise their accounts. From an ATT&CK framework perspective, this vulnerability maps to T1531 (Run-time Application Substitution) and T1059.007 (Command and Scripting Interpreter: JavaScript), as it allows adversaries to execute JavaScript code within the context of legitimate user sessions. The widespread adoption of vBulletin 4.1.12 across various organizations and websites amplifies the potential damage, as a single compromised forum could serve as a vector for attacks against multiple user populations.
Organizations affected by this vulnerability should implement immediate mitigations including input validation, output encoding, and proper content sanitization measures. The most effective immediate solution involves implementing strict input validation that limits the length and content of subject parameters, combined with proper HTML escaping of all user-supplied data before rendering. Security patches released by vBulletin for this specific vulnerability should be applied immediately, as they address the core input sanitization issues. Additional defensive measures include implementing content security policies that restrict script execution within forum environments and monitoring for suspicious posting patterns that might indicate exploitation attempts. Network-based intrusion detection systems should be configured to detect and alert on known malicious payload patterns associated with this vulnerability. The remediation process should also include user education about the risks of clicking on suspicious links or content within forum environments, as social engineering remains a critical component in successful exploitation of such vulnerabilities.