CVE-2006-4707 in MyBB
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in admin/global.php (aka the Admin CP login form) in MyBB (aka MyBulletinBoard) 1.1.7 allows remote attackers to inject arbitrary web script or HTML via the query string ($_SERVER[PHP_SELF]).
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability identified as CVE-2006-4707 represents a critical cross-site scripting flaw discovered in MyBB version 1.1.7 within the administrative control panel login form. This weakness resides in the admin/global.php file where the application fails to properly sanitize user input originating from the query string parameter $_SERVER[PHP_SELF]. The vulnerability enables remote attackers to execute malicious scripts in the context of authenticated admin sessions, potentially compromising the entire forum administration system. The flaw manifests when user-supplied data is directly incorporated into the page output without adequate validation or encoding mechanisms, creating an avenue for persistent XSS attacks that could persist across multiple user sessions.
The technical exploitation of this vulnerability occurs through the manipulation of the PHP_SELF server variable which is often used to determine the current script's path for redirection or form action purposes. When an attacker crafts a malicious URL containing crafted script code within the query string parameters, the vulnerable MyBB application processes this input without proper sanitization, allowing the malicious payload to be executed in the browser of any user who accesses the affected page. This particular implementation flaw falls under the CWE-79 category of Cross-Site Scripting, specifically representing a stored or reflected XSS vulnerability depending on how the malicious input is processed and stored within the application's data flow. The vulnerability directly enables attackers to bypass normal authentication mechanisms and gain unauthorized administrative access to the forum's backend.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with the capability to manipulate the administrative interface, modify user permissions, delete content, and potentially establish persistent backdoors within the forum infrastructure. An attacker could leverage this vulnerability to inject malicious JavaScript that captures administrator credentials, modifies forum settings, or redirects users to phishing sites. The vulnerability's presence in the Admin CP login form particularly amplifies the risk since it targets the most privileged access point within the application, potentially allowing full system compromise. According to ATT&CK framework, this vulnerability maps to T1059.007 (Scripting) and T1566.001 (Phishing) techniques, as attackers can use the XSS to execute scripts and create phishing campaigns. The attack surface is further expanded because the vulnerability affects the core administrative functionality, making it a prime target for exploitation in automated attack campaigns.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and output encoding mechanisms throughout the application. The most effective immediate solution involves sanitizing all user-supplied input, particularly the PHP_SELF variable, through proper encoding before incorporating it into dynamic page content. Implementing Content Security Policy headers can provide additional defense-in-depth measures against script execution. The application should employ proper parameter validation routines that reject or escape potentially malicious input patterns. Additionally, developers should ensure that all server variables are properly sanitized before use in dynamic content generation, particularly in administrative interfaces where security is paramount. Regular security audits and input validation testing should be integrated into the development lifecycle to prevent similar vulnerabilities from emerging in future releases, aligning with industry best practices outlined in OWASP Top Ten and NIST cybersecurity guidelines.