CVE-2011-5132 in MyBB
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in MyBB before 1.6.5 allows remote attackers to inject arbitrary web script or HTML via vectors related to "usernames via AJAX."
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Analysis
by VulDB Data Team • 02/20/2019
The CVE-2011-5132 vulnerability represents a critical cross-site scripting flaw discovered in MyBB versions prior to 1.6.5, specifically affecting the forum software's handling of user input through asynchronous javascript requests. This vulnerability resides in the application's username validation and display mechanisms when processing ajax-based user interactions, creating a pathway for malicious actors to execute arbitrary web scripts within the context of other users' browsers. The flaw exploits the insecure handling of user-provided data during dynamic content loading operations, where usernames submitted through ajax requests are not properly sanitized before being rendered in the user interface.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within MyBB's ajax username checking functionality. When users submit usernames through ajax-enabled forms, the application fails to adequately escape special characters and html markup that could be interpreted as executable code by web browsers. This allows attackers to craft malicious usernames containing javascript payloads or html tags that execute when other users view the affected content. The vulnerability is particularly dangerous because it leverages the legitimate ajax functionality of the platform, making the malicious code execution appear to originate from a trusted source within the application itself.
From an operational impact perspective, this vulnerability enables attackers to perform various malicious activities including session hijacking, credential theft, and redirection to malicious websites. An attacker could inject javascript code that steals cookies or session tokens from unsuspecting users, potentially gaining unauthorized access to their accounts and forum privileges. The vulnerability also allows for defacement of forum content, injection of malicious advertisements, or redirection to phishing sites that could compromise user credentials. The remote nature of the attack means that exploitation does not require any special privileges or local access to the target system, making it particularly attractive to attackers seeking to compromise multiple users simultaneously.
The vulnerability aligns with CWE-79, which describes cross-site scripting flaws in web applications, and maps to attack techniques within the MITRE ATT&CK framework under the 'Command and Control' and 'Initial Access' phases. Organizations using affected MyBB versions face significant risk of unauthorized access and data compromise, particularly in environments where forum users may be trusted with elevated privileges or where sensitive user information is collected. The impact is exacerbated by the widespread adoption of MyBB in various online communities and the typical lack of security awareness among forum users who may inadvertently click on malicious links or content.
Mitigation strategies for CVE-2011-5132 require immediate implementation of the official MyBB 1.6.5 patch which addresses the input sanitization issues in the ajax username handling code. Organizations should also implement additional security measures including regular security audits of web applications, input validation on all user-provided data, and output encoding of dynamic content. Network-level protections such as web application firewalls can provide additional defense-in-depth, while user education regarding suspicious forum activity and link clicking remains essential. Regular monitoring for signs of exploitation including unusual traffic patterns or unauthorized user activities should be implemented to detect potential compromise of the affected systems.