CVE-2011-3371 in PunBB
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in include/functions.php in PunBB before 1.3.6 allow remote attackers to inject arbitrary web script or HTML via the (1) id, (2) form_sent, (3) csrf_token, (4) req_confirm, or (5) delete parameter to delete.php, the (6) id, (7) form_sent, (8) csrf_token, (9) req_message, or (10) submit parameter to edit.php, the (11) action, (12) form_sent, (13) csrf_token, (14) req_email, or (15) request_pass parameter to login.php, the (16) email, (17) form_sent, (18) redirect_url, (19) csrf_token, (20) req_subject, (21) req_message, or (22) submit parameter to misc.php, the (23) action, (24) id, (25) form_sent, (26) csrf_token, (27) req_old_password, (28) req_new_password1, (29) req_new_password2, or (30) update parameter to profile.php, or the (31) action, (32) form_sent, (33) csrf_token, (34) req_username, (35) req_password1, (36) req_password2, (37) req_email1, (38) timezone, or (39) register parameter to register.php.
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Analysis
by VulDB Data Team • 11/20/2021
The vulnerability identified as CVE-2011-3371 represents a critical cross-site scripting flaw affecting PunBB versions prior to 1.3.6. This issue stems from inadequate input validation and output sanitization mechanisms within the forum software's core functions file. The vulnerability manifests across multiple PHP scripts including delete.php, edit.php, login.php, misc.php, profile.php, and register.php, making it particularly dangerous as it affects fundamental user interaction points within the application. The flaw allows remote attackers to inject malicious web scripts or HTML content through various parameters, creating persistent XSS attack vectors that can compromise user sessions and data integrity.
The technical nature of this vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws where untrusted data is improperly incorporated into web pages without proper validation or encoding. The vulnerability occurs because PunBB fails to sanitize user-supplied input parameters before rendering them in web responses, creating opportunities for attackers to execute malicious scripts in the context of other users' browsers. The affected parameters span across different functional areas of the application, including authentication flows, profile management, message handling, and registration processes, demonstrating the widespread impact of the flawed input handling mechanisms.
From an operational perspective, this vulnerability poses significant risks to both end users and system administrators. Attackers can exploit these XSS vectors to steal session cookies, redirect users to malicious sites, deface forum content, or perform actions on behalf of authenticated users. The impact extends beyond simple data theft as attackers can leverage these vulnerabilities to establish persistent access to the forum, manipulate user data, and potentially use the compromised forum as a stepping stone for broader network attacks. The vulnerability's presence in core authentication and user management functions makes it particularly attractive to threat actors seeking to escalate privileges or maintain long-term access to the platform.
The attack surface of CVE-2011-3371 aligns with ATT&CK technique T1531 which involves the use of credentials to gain access to systems or data. The vulnerability's exploitation requires minimal technical skill and can be automated, making it a preferred target for mass exploitation campaigns. Organizations running vulnerable PunBB installations face immediate risk of user data compromise, reputational damage, and potential regulatory compliance violations. The lack of proper input sanitization in the functions.php file indicates fundamental security weaknesses in the application's architecture that extend beyond this single vulnerability to potentially affect other areas of the codebase.
Mitigation strategies for this vulnerability involve immediate patching to PunBB version 1.3.6 or later, which implements proper input validation and output encoding mechanisms. System administrators should also implement additional security measures including content security policies, input validation at multiple layers, and regular security audits of web applications. The vulnerability demonstrates the importance of proper parameter sanitization and the principle of least privilege in web application security, where all user-supplied data should be treated as potentially malicious until properly validated and encoded. Organizations should also consider implementing web application firewalls and monitoring for suspicious parameter patterns that could indicate exploitation attempts.