CVE-2006-4449 in MyBB
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in attachment.php in MyBulletinBoard (MyBB) 1.1.7 and possibly other versions allows remote attackers to inject arbitrary web script or HTML via a GIF image that contains URL-encoded Javascript, which is rendered by Internet Explorer.
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability identified as CVE-2006-4449 represents a critical cross-site scripting flaw within MyBulletinBoard version 1.1.7 and potentially other iterations of the platform. This security weakness resides in the attachment.php script which processes user-uploaded files, specifically targeting the handling of GIF image attachments. The flaw enables malicious actors to execute arbitrary web scripts or HTML code through crafted image files that contain URL-encoded javascript within their metadata or content structure.
This vulnerability operates through a sophisticated exploitation vector that leverages Internet Explorer's rendering behavior when processing certain image formats. The attack mechanism involves uploading a specially crafted GIF file that contains embedded javascript code in an encoded format. When the vulnerable MyBB system processes this attachment and renders it within the web interface, Internet Explorer executes the embedded script, effectively bypassing standard security restrictions. The vulnerability is particularly dangerous because it exploits the trust relationship between the web application and the browser, allowing attackers to inject malicious code that can execute in the context of the victim's session.
The operational impact of this vulnerability extends far beyond simple script injection, creating significant risks for user data and system integrity. Attackers can leverage this flaw to steal session cookies, redirect users to malicious sites, deface forum content, or execute more sophisticated attacks such as credential theft or privilege escalation. The vulnerability affects the core functionality of the bulletin board system, potentially compromising all users who view the malicious attachment, making it a high-severity threat that could impact entire user communities. The specific targeting of Internet Explorer renders this vulnerability particularly concerning given the browser's widespread adoption and the complex security model it employs for handling various file types.
Mitigation strategies for this vulnerability should encompass both immediate remediation and long-term architectural improvements. The most effective immediate solution involves applying the official patch released by MyBB developers to address the XSS vulnerability in the attachment handling mechanism. Organizations should also implement strict file validation and sanitization processes that filter out potentially malicious content from uploaded attachments, particularly focusing on image file metadata inspection. Network-level protections including web application firewalls and content filtering systems can provide additional defense layers, while user education regarding suspicious attachments remains crucial. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and maps to ATT&CK technique T1566 related to phishing with malicious attachments, highlighting the multi-faceted nature of the threat landscape this vulnerability creates. Regular security audits and input validation testing should become standard practices to prevent similar issues in future software deployments.