CVE-2005-0258 in phpBB
Summary
by MITRE
Directory traversal vulnerability in (1) usercp_register.php and (2) usercp_avatar.php for phpBB 2.0.11, and possibly other versions, with gallery avatars enabled, allows remote attackers to delete (unlink) arbitrary files via "/../" sequences in the avatarselect parameter.
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Analysis
by VulDB Data Team • 06/05/2019
This vulnerability exists in phpBB version 2.0.11 and potentially other versions where gallery avatars are enabled. The flaw manifests in two specific files usercp_register.php and usercp_avatar.php which fail to properly validate user input containing directory traversal sequences. Attackers can exploit this weakness by crafting malicious requests with "/../" sequences in the avatarselect parameter to manipulate file paths and gain unauthorized access to the file system. The vulnerability stems from insufficient input sanitization and path validation mechanisms within the phpBB application's user control panel functionality. When gallery avatars are enabled, the application processes user-supplied avatar selection parameters without adequate filtering to prevent directory traversal attacks, allowing malicious actors to bypass normal file access controls and potentially delete arbitrary files on the server. This represents a critical security flaw that directly violates the principle of least privilege and can lead to complete system compromise. The vulnerability aligns with CWE-22 which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal. From an operational perspective, this vulnerability enables attackers to perform unauthorized file operations including deletion of critical system files, modification of application files, or access to sensitive data stored on the server. The attack vector is particularly dangerous because it allows remote exploitation without requiring authentication, making it a significant threat to web application security. The impact extends beyond simple file deletion as attackers could potentially overwrite critical application files, inject malicious code, or access database files and configuration settings. This vulnerability also maps to several ATT&CK techniques including T1059 for command and scripting interpreter and T1078 for valid accounts, as attackers may leverage the compromised system to maintain persistence or escalate privileges. The attack requires minimal technical expertise to execute, making it particularly dangerous for widely deployed applications like phpBB which powers numerous forums and community platforms. Organizations running affected phpBB versions should immediately implement mitigations including input validation patches, disabling gallery avatars if not required, and implementing proper access controls. The vulnerability demonstrates the critical importance of proper input validation in web applications and highlights how seemingly simple flaws can lead to complete system compromise. Security practitioners should conduct comprehensive audits of all web applications to identify similar directory traversal vulnerabilities and ensure proper implementation of path validation mechanisms. The vulnerability also underscores the necessity of regular security updates and the risks associated with running outdated web application versions in production environments.