CVE-2006-1625 in MyBB
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in inc/functions_post.php in MyBB (aka MyBulletinBoard) 1.10 allows remote attackers to inject arbitrary web script or HTML via a JavaScript event in a BBCode email tag, as demonstrated using the onmousemove event.
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability identified as CVE-2006-1625 represents a critical cross-site scripting flaw within the MyBulletinBoard forum software version 1.10, specifically affecting the inc/functions_post.php file. This vulnerability exposes the application to malicious injection attacks where remote attackers can execute arbitrary web scripts or HTML code through carefully crafted input. The flaw manifests when the application processes BBCode email tags without proper sanitization of JavaScript events, creating an avenue for persistent malicious code execution within user sessions.
The technical mechanism behind this vulnerability involves the improper handling of user input within the BBCode parsing functionality. When a user submits content containing an email tag with embedded JavaScript events such as onmousemove, the application fails to adequately sanitize or escape these events before rendering them in the browser context. This lack of input validation creates a direct pathway for attackers to inject malicious scripts that execute in the context of other users' browsers. The vulnerability specifically targets the email tag functionality within BBCode, which is a common formatting option in bulletin board systems for creating clickable email links.
From an operational perspective, this XSS vulnerability poses significant risks to both user privacy and application integrity. Successful exploitation allows attackers to hijack user sessions, steal sensitive information, manipulate forum content, or redirect users to malicious websites. The impact extends beyond individual user accounts as forum administrators may inadvertently expose themselves to attacks through compromised user sessions or by viewing maliciously crafted posts. The vulnerability's persistence in the application's core functionality means that any user who views a maliciously crafted post containing the injected script becomes a potential victim, creating a widespread attack surface across the entire forum community.
The vulnerability aligns with CWE-79, which defines Cross-Site Scripting as a weakness where software does not properly neutralize user-controllable input before it is used in the generation of web output. This classification emphasizes the fundamental flaw in input validation and output encoding practices within the application. From an ATT&CK framework perspective, this vulnerability maps to T1566.001, representing the use of malicious HTML files in phishing attacks, and T1059.007, which covers the use of JavaScript in command and control communications. The attack vector specifically leverages the web application's trust in user input without proper sanitization, creating a persistent threat that can be exploited across multiple user sessions and forum interactions.
Mitigation strategies for this vulnerability require immediate implementation of proper input sanitization and output encoding mechanisms. The application must implement comprehensive validation of all user-submitted content, particularly within BBCode parsing functions, to prevent JavaScript event handlers from being executed. This includes implementing strict content filtering that removes or encodes potentially dangerous attributes such as onmousemove, onclick, and other browser event handlers. Additionally, the application should employ proper HTML escaping mechanisms for all user-generated content rendered in web pages, ensuring that any special characters are properly encoded to prevent script execution. Security patches should be applied immediately to update the vulnerable inc/functions_post.php file, and administrators should consider implementing a Content Security Policy to add an additional layer of protection against script injection attacks. Regular security audits of input validation mechanisms and comprehensive testing of BBCode functionality should be conducted to prevent similar vulnerabilities from emerging in future versions of the application.