CVE-2001-0320 in PHP-Nuke
Summary
by MITRE
bb_smilies.php and bbcode_ref.php in PHP-Nuke 4.4 allows remote attackers to read arbitrary files and gain PHP administrator privileges by inserting a null character and .. (dot dot) sequences into a malformed username argument.
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Analysis
by VulDB Data Team • 05/12/2019
The vulnerability identified as CVE-2001-0320 represents a critical security flaw in PHP-Nuke 4.4 affecting two key script files: bb_smilies.php and bbcode_ref.php. This vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data, particularly username arguments. The flaw allows remote attackers to exploit path traversal mechanisms through carefully crafted malicious inputs containing null characters and directory traversal sequences, creating a pathway for unauthorized access to sensitive system resources.
The technical exploitation of this vulnerability relies on the manipulation of input parameters through null byte injection and directory traversal sequences. Attackers can craft malicious username arguments that contain null characters followed by .. (dot dot) sequences, which when processed by the vulnerable scripts can bypass normal file access controls. This type of attack directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability essentially allows attackers to manipulate the file system access paths through improper input validation, enabling them to navigate to arbitrary directories and potentially access sensitive files including configuration files, database credentials, and other administrative resources.
The operational impact of this vulnerability is severe and multifaceted, potentially enabling complete system compromise. When successfully exploited, attackers can read arbitrary files from the server filesystem, which may include database connection details, administrative credentials, and other sensitive information. The ability to gain PHP administrator privileges through this method represents a complete escalation of privileges, allowing attackers to execute arbitrary code, modify system files, and potentially establish persistent backdoors. This vulnerability directly aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, where attackers can leverage the compromised system to execute malicious commands through the PHP interpreter.
The attack vector for this vulnerability is particularly concerning as it requires no authentication to exploit, making it highly dangerous in environments where PHP-Nuke is deployed. The flaw exists in the core functionality of the bulletin board system, specifically in how it processes user-generated content for smiley and bbcode display functions. This type of vulnerability demonstrates the importance of proper input sanitization and the principle of least privilege in web application security. The exploitation technique leverages the fundamental weakness in the application's handling of user-supplied data, where null byte injection combined with directory traversal sequences can bypass security controls that should prevent such access patterns.
Organizations affected by this vulnerability should immediately implement mitigation strategies including input validation, proper file access controls, and application-level security hardening. The recommended remediation involves updating to patched versions of PHP-Nuke, implementing proper input sanitization mechanisms, and applying web application firewalls to filter malicious requests. Additionally, this vulnerability highlights the critical need for regular security assessments and input validation testing to prevent similar issues in other web applications. The vulnerability serves as a prime example of why security-by-design principles are essential, particularly in applications handling user-generated content, where proper validation and sanitization of all inputs should be implemented at every layer of the application architecture.