CVE-2005-3319 in apache2handler SAPI
Summary
by MITRE
The apache2handler SAPI (sapi_apache2.c) in the Apache module (mod_php) for PHP 5.x before 5.1.0 final and 4.4 before 4.4.1 final allows attackers to cause a denial of service (segmentation fault) via the session.save_path option in a .htaccess file or VirtualHost.
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Analysis
by VulDB Data Team • 06/15/2019
The vulnerability described in CVE-2005-3319 represents a critical denial of service weakness within the Apache module for PHP, specifically affecting the apache2handler SAPI implementation. This flaw exists in mod_php versions prior to the final releases of PHP 5.1.0 and PHP 4.4.1, creating a scenario where malicious actors can exploit the session.save_path configuration option to trigger segmentation faults in the Apache web server process. The vulnerability is particularly concerning because it can be executed through .htaccess files or VirtualHost configurations, making it accessible to attackers who may not have direct server access but can influence web application deployment settings.
The technical root cause of this vulnerability stems from improper validation and handling of the session.save_path directive within the apache2handler SAPI module. When PHP processes session data and encounters a malformed or maliciously crafted session.save_path value in the .htaccess file or VirtualHost configuration, the module fails to properly validate the input before attempting to use it for session storage operations. This lack of input sanitization leads to memory corruption conditions that ultimately result in segmentation faults, causing the Apache process to crash and terminate unexpectedly. The vulnerability manifests specifically during session initialization or data handling phases when the system attempts to create or access session files in the specified directory path.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged to create persistent denial of service conditions that affect legitimate users accessing the web application. Attackers can repeatedly trigger the segmentation fault by manipulating the session.save_path value to point to invalid or inaccessible directories, causing the Apache server to continuously crash and restart. This creates a cascading effect that can overwhelm server resources, particularly in environments where the web server is configured to automatically restart crashed processes. The vulnerability is especially dangerous in high-traffic environments where such attacks can be used to systematically degrade service availability, potentially leading to complete unavailability of the affected web applications.
From a security framework perspective, this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation leading to memory corruption. The attack pattern follows the ATT&CK technique T1499.004 for Network Denial of Service, where adversaries exploit application-level vulnerabilities to disrupt service availability. Organizations should implement immediate mitigations including updating to PHP versions 5.1.0 or later and 4.4.1 or later, where the vulnerability has been addressed through proper input validation and error handling mechanisms. Additionally, administrators should restrict write permissions on .htaccess files and implement proper configuration management practices to prevent unauthorized modifications to session handling parameters. The vulnerability underscores the importance of input validation in web application modules and demonstrates how seemingly benign configuration options can become attack vectors when not properly secured against malicious input manipulation.