CVE-2006-2828 in PHP-Nuke
Summary
by MITRE
Global variable overwrite vulnerability in PHP-Nuke allows remote attackers to conduct remote PHP file inclusion attacks via a modified phpbb_root_path parameter to the admin scripts (1) index.php, (2) admin_ug_auth.php, (3) admin_board.php, (4) admin_disallow.php, (5) admin_forumauth.php, (6) admin_groups.php, (7) admin_ranks.php, (8) admin_styles.php, (9) admin_user_ban.php, (10) admin_words.php, (11) admin_avatar.php, (12) admin_db_utilities.php, (13) admin_forum_prune.php, (14) admin_forums.php, (15) admin_mass_email.php, (16) admin_smilies.php, (17) admin_ug_auth.php, and (18) admin_users.php, which overwrites $phpbb_root_path when the import_request_variables function is executed after $phpbb_root_path has been initialized to a static value.
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Analysis
by VulDB Data Team • 09/18/2017
The vulnerability described in CVE-2006-2828 represents a critical security flaw in PHP-Nuke versions prior to 7.9, specifically targeting the global variable overwrite mechanism that enables remote code execution through PHP file inclusion attacks. This vulnerability stems from improper handling of user-supplied input within the administration scripts of the PHP-Nuke content management system, creating a pathway for attackers to manipulate critical global variables and subsequently execute arbitrary PHP code on the target server. The flaw is particularly dangerous because it affects multiple administrative endpoints, amplifying the potential impact of a successful exploitation attempt.
The technical implementation of this vulnerability relies on the improper use of the import_request_variables function in PHP, which allows attackers to overwrite pre-initialized global variables including $phpbb_root_path. When an attacker supplies a modified phpbb_root_path parameter through the affected administrative scripts, the function executes after the variable has already been set to a static value, resulting in the variable being overwritten with attacker-controlled data. This overwrite creates a condition where subsequent code execution can utilize the maliciously modified path, enabling remote attackers to include arbitrary PHP files from remote locations. The vulnerability is classified under CWE-120, which specifically addresses Buffer Overflow in a Character String, and more broadly under CWE-94, which covers the execution of arbitrary code due to improper input validation.
The operational impact of this vulnerability extends far beyond simple data compromise, as successful exploitation can lead to complete system compromise and unauthorized access to sensitive server resources. Attackers can leverage this vulnerability to execute malicious PHP code, potentially gaining shell access to the web server, accessing databases, modifying content, or establishing persistent backdoors. The fact that this vulnerability affects multiple administrative scripts increases the attack surface significantly, as different endpoints may provide different levels of access or functionality to the attacker. The attack vector requires only that an attacker can access the administrative interface, which is often protected by authentication but may be bypassed through other means or exploited when administrative credentials are compromised.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to command and control operations and privilege escalation. The technique of global variable overwrite falls under the category of code injection attacks, and the remote file inclusion aspect corresponds to ATT&CK technique T1190, which covers exploits for execution through remote file inclusion vulnerabilities. Organizations affected by this vulnerability should implement immediate mitigations including upgrading to PHP-Nuke version 7.9 or later, implementing proper input validation and sanitization for all user-supplied parameters, and restricting access to administrative interfaces through network segmentation and authentication controls. Additionally, the use of web application firewalls and regular security audits can help detect and prevent exploitation attempts. The vulnerability demonstrates the critical importance of proper variable handling in PHP applications and serves as a reminder of the need for comprehensive input validation and the principle of least privilege in web application security design.