CVE-2002-1537 in phpBB
Summary
by MITRE
admin_ug_auth.php in phpBB 2.0.0 allows local users to gain administrator privileges by directly calling admin_ug_auth.php with modifed form fields such as "u".
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Analysis
by VulDB Data Team • 09/05/2025
The vulnerability described in CVE-2002-1537 represents a critical access control flaw in phpBB version 2.0.0 that allows local users to escalate their privileges to administrator level. This issue stems from inadequate input validation and authentication checks within the administrative user group authorization component of the forum software. The specific file admin_ug_auth.php fails to properly verify user permissions before processing administrative actions, creating a pathway for unauthorized privilege escalation.
The technical exploitation of this vulnerability occurs through direct manipulation of form fields in the administrative interface. Attackers can bypass normal authentication procedures by directly calling admin_ug_auth.php and modifying the "u" parameter to reference a target user account. This manipulation allows attackers to perform administrative functions without proper authorization, effectively granting them complete control over user management and group permissions within the phpBB installation. The vulnerability essentially removes the authentication checks that should prevent unauthorized access to administrative functions, making it a classic example of insecure direct object reference.
The operational impact of this vulnerability is severe as it enables attackers to completely compromise the administrative integrity of phpBB installations. Once exploited, attackers can modify user permissions, add new administrators, delete users, and manipulate forum content with full administrative privileges. This represents a significant risk to forum administrators and their users, as it allows for complete system takeover and potential data exfiltration or corruption. The vulnerability affects any local user with access to the phpBB installation, making it particularly dangerous in multi-user environments where access control is paramount.
This vulnerability maps directly to CWE-285, which addresses insufficient authorization issues in software systems. The flaw demonstrates poor privilege management and inadequate input validation practices that violate fundamental security principles. From an ATT&CK framework perspective, this vulnerability aligns with privilege escalation techniques under the T1068 category, specifically targeting the manipulation of administrative access controls. Organizations should implement proper input validation, enforce strict access controls, and regularly update their software to prevent such exploitation paths. The recommended mitigations include patching to newer phpBB versions, implementing proper authentication checks, and ensuring that administrative functions require proper authorization before execution. Additionally, organizations should consider implementing web application firewalls and monitoring for suspicious parameter manipulation attempts to detect potential exploitation attempts.