CVE-2011-5131 in MyBB
Summary
by MITRE
Cross-site request forgery (CSRF) vulnerability in global.php in MyBB before 1.6.5 allows remote attackers to hijack the authentication of a user for requests that change the user s language via the language parameter.
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Analysis
by VulDB Data Team • 12/12/2021
The CVE-2011-5131 vulnerability represents a critical cross-site request forgery flaw discovered in MyBB versions prior to 1.6.5, specifically within the global.php file. This vulnerability operates by exploiting the absence of proper authentication verification mechanisms when processing user language preference changes, creating a significant security risk for web applications built on the MyBB platform. The flaw enables remote attackers to manipulate user sessions and potentially execute unauthorized actions by leveraging the trust relationship between the vulnerable application and its users.
The technical implementation of this CSRF vulnerability stems from the application's failure to validate the authenticity of requests originating from the user's browser. When a user navigates to a malicious website or clicks on a crafted link, the attacker can construct a request that automatically submits a language change parameter to the MyBB application. Since the application does not require proper authentication tokens or referer validation for this particular parameter, the malicious request executes with the privileges of the authenticated user. This vulnerability specifically targets the language parameter, which when modified can potentially alter the user interface behavior and potentially redirect to attacker-controlled content.
The operational impact of this vulnerability extends beyond simple language preference changes, as it demonstrates a fundamental flaw in the application's session management and request validation mechanisms. Attackers can leverage this weakness to perform unauthorized actions that could compromise user accounts, manipulate application settings, or potentially escalate privileges within the MyBB environment. The vulnerability is particularly dangerous because it requires no privileged access or complex exploitation techniques, making it accessible to attackers with minimal technical skills. Users who visit malicious websites or click on compromised links become unwitting participants in the attack, as their browsers automatically submit requests to the vulnerable MyBB application.
This vulnerability aligns with CWE-352, which specifically addresses cross-site request forgery weaknesses in web applications, and demonstrates the critical importance of implementing proper anti-CSRF measures such as token validation, referer header checks, or SameSite cookie attributes. From an ATT&CK framework perspective, this vulnerability maps to techniques involving session management manipulation and credential compromise, potentially enabling adversaries to maintain persistent access to user accounts. The attack surface is particularly concerning in environments where MyBB is used for community forums or user-managed platforms, as these applications often store sensitive user information and provide administrative capabilities. The vulnerability also highlights the importance of proper input validation and authentication checks for all parameters that modify application state, regardless of their apparent simplicity or functionality.
Mitigation strategies for CVE-2011-5131 involve implementing robust anti-CSRF mechanisms such as synchronizer tokens, referer header validation, or SameSite cookie attributes to prevent unauthorized request execution. Organizations should immediately upgrade to MyBB version 1.6.5 or later, which includes proper CSRF protection measures. Additionally, administrators should conduct security audits to identify similar vulnerabilities in other application components and implement comprehensive input validation for all user-controllable parameters. The vulnerability serves as a reminder of the critical importance of maintaining current security patches and implementing defense-in-depth strategies to protect web applications from session hijacking and unauthorized access attempts.