CVE-2004-0530 in PHP
Summary
by MITRE
The PHP package in Slackware 8.1, 9.0, and 9.1, when linked against a static library, includes /tmp in the search path, which allows local users to execute arbitrary code as the PHP user by inserting shared libraries into the appropriate path.
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Analysis
by VulDB Data Team • 07/07/2017
The vulnerability described in CVE-2004-0530 represents a critical security flaw in the PHP package distribution within Slackware operating systems version 8.1, 9.0, and 9.1. This issue specifically manifests when PHP is compiled and linked against static libraries, creating an insecure environment where the /tmp directory becomes part of the library search path. The fundamental problem lies in the improper handling of library loading sequences during the PHP execution process, which creates an exploitable condition that can be leveraged by local attackers to gain elevated privileges.
The technical implementation of this vulnerability stems from the insecure library path configuration that occurs during the static linking process of PHP. When PHP is built with static libraries, the dynamic linker's search path includes the /tmp directory, which is typically world-writable and accessible to unprivileged users. This configuration allows a local attacker to place malicious shared libraries in the /tmp directory with the same filenames as those expected by PHP during execution. When PHP attempts to load these libraries, it will instead load the attacker-controlled malicious libraries, executing arbitrary code with the privileges of the PHP user account, typically running as the web server user.
The operational impact of this vulnerability is significant as it provides a local privilege escalation vector that can be exploited by any user with access to the system. The attack requires no network connectivity and can be executed entirely from within the local environment, making it particularly dangerous in multi-user systems where untrusted users might have access to the system. The vulnerability essentially allows an attacker to bypass normal access controls and execute code with the privileges of the PHP user, which often corresponds to the web server user account and may have access to web application data and system resources.
This vulnerability aligns with CWE-426, which describes the insecure loading of dynamic libraries, and represents a classic example of a privilege escalation attack through library injection. The flaw also maps to ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', and T1548.001, which covers 'Abuse Elevation Control Mechanism'. The attack vector specifically demonstrates how insecure library loading can be exploited to gain elevated privileges through the manipulation of the library search path.
Mitigation strategies for this vulnerability require immediate system updates and configuration changes to address the insecure library path. The primary solution involves updating the PHP package to a version that properly handles library loading without including world-writable directories in the search path. Administrators should also implement proper file system permissions, ensuring that the /tmp directory and other temporary locations are properly secured with appropriate access controls. Additionally, the system should be configured to use secure library loading mechanisms that do not include potentially compromised directories in the search path, and regular security audits should be conducted to verify that no insecure library configurations exist. The vulnerability underscores the importance of secure coding practices and proper library management in system security.