CVE-2003-0097 in PHP
Summary
by MITRE
Unknown vulnerability in CGI module for PHP 4.3.0 allows attackers to access arbitrary files as the PHP user, and possibly execute PHP code, by bypassing the CGI force redirect settings (cgi.force_redirect or --enable-force-cgi-redirect).
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Analysis
by VulDB Data Team • 08/25/2025
The vulnerability described in CVE-2003-0097 represents a critical security flaw in the PHP CGI module that emerged in version 4.3.0, affecting web server configurations that utilize PHP in CGI mode. This issue stems from a fundamental misconfiguration in how PHP handles file access controls when operating through the Common Gateway Interface, creating a pathway for attackers to bypass essential security mechanisms designed to protect system resources. The vulnerability specifically targets the cgi.force_redirect directive, which serves as a crucial security control that prevents unauthorized access to PHP scripts and system files through direct URL manipulation.
The technical exploitation of this vulnerability occurs when the cgi.force_redirect setting is either disabled or improperly configured in the PHP configuration file. This misconfiguration allows attackers to craft malicious URLs that can traverse the file system and access files that should normally be restricted to the PHP user context. The flaw operates by circumventing the intended security boundaries that separate web-accessible content from sensitive system files, enabling attackers to read arbitrary files on the server that are typically protected by proper access controls. When this vulnerability is successfully exploited, it can potentially lead to remote code execution, as attackers may be able to inject and execute PHP code directly on the server, thereby gaining unauthorized access to the system.
The operational impact of CVE-2003-0097 extends beyond simple file access, as it fundamentally compromises the security model of PHP applications running in CGI mode. Attackers can leverage this vulnerability to access sensitive configuration files, database credentials, application source code, and other confidential information that should remain protected. The vulnerability is particularly dangerous because it operates at the core level of PHP's file access mechanisms, potentially allowing attackers to escalate privileges and move laterally within the compromised environment. This issue directly relates to CWE-22, which describes improper limitation of a pathname to a restricted directory, and aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could enable attackers to execute arbitrary commands through PHP code execution capabilities.
Mitigation strategies for this vulnerability require immediate attention to PHP configuration settings, specifically ensuring that cgi.force_redirect is properly enabled and configured in the php.ini file. System administrators should verify that the directive is set to 1 or true, which forces PHP to validate that requests are coming through the CGI interface rather than being directly accessed. Additionally, organizations should implement proper web server configuration to prevent direct access to PHP files and ensure that all PHP applications are running with the minimum required privileges. The fix involves updating the PHP configuration to enforce proper redirect validation and implementing robust access controls that prevent unauthorized file access through the CGI interface. Regular security audits should verify that all PHP installations maintain proper security configurations, and monitoring systems should be implemented to detect suspicious file access patterns that might indicate exploitation attempts.