CVE-1999-0238 in PHP
Summary
by MITRE
php.cgi allows attackers to read any file on the system.
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Analysis
by VulDB Data Team • 07/10/2024
The vulnerability identified as CVE-1999-0238 represents a critical directory traversal flaw in the php.cgi component that was prevalent in early web server configurations. This issue specifically affects systems where PHP is executed through CGI interfaces, creating a pathway for unauthorized file access that can compromise entire server environments. The vulnerability stems from insufficient input validation within the php.cgi script, allowing malicious users to manipulate file path parameters and gain access to arbitrary files on the underlying operating system.
The technical implementation of this vulnerability exploits the lack of proper sanitization in the CGI interface handling of PHP requests. When php.cgi processes user input, it fails to adequately validate or sanitize file paths that are passed through query parameters or form data. Attackers can leverage this weakness by crafting malicious requests that include directory traversal sequences such as ../ or ..\, which when processed by the vulnerable script can navigate beyond the intended document root and access sensitive system files including configuration files, password databases, and other restricted resources. This flaw operates at the application layer and can be exploited through web browser interfaces or automated attack tools without requiring elevated privileges on the target system.
The operational impact of CVE-1999-0238 extends far beyond simple unauthorized file access, as it provides attackers with potential access to critical system information that can facilitate further compromise of the affected environment. An attacker who successfully exploits this vulnerability can retrieve sensitive files such as /etc/passwd, /etc/shadow, or web server configuration files that contain database credentials, encryption keys, and other confidential information. This access can enable attackers to escalate their privileges, conduct reconnaissance for additional vulnerabilities, or extract data that can be used for identity theft, financial fraud, or system takeover operations. The vulnerability is particularly dangerous because it can be exploited remotely without authentication, making it a preferred target for automated scanning and exploitation tools.
Mitigation strategies for CVE-1999-0238 require immediate implementation of input validation controls and proper system hardening measures. Organizations should implement strict file path validation within PHP applications and ensure that all user-supplied input is properly sanitized before being processed by the CGI interface. The recommended approach includes deploying web application firewalls that can detect and block malicious traversal sequences, restricting access to sensitive system directories through proper file permissions, and implementing proper input filtering mechanisms that prevent directory traversal attacks. Additionally, organizations should consider migrating from CGI-based PHP execution to more secure interfaces such as mod_php or PHP-FPM that provide better isolation and security controls. This vulnerability aligns with CWE-22 Directory Traversal and is categorized under ATT&CK technique T1083 File and Directory Discovery, highlighting its role in reconnaissance activities that precede more sophisticated attacks. The vulnerability also demonstrates the importance of following secure coding practices and proper input validation as outlined in OWASP Top Ten security principles, particularly focusing on preventing path traversal attacks through proper application design and implementation.