CVE-2002-2309 in PHP
Summary
by MITRE
php.exe in PHP 3.0 through 4.2.2, when running on Apache, does not terminate properly, which allows remote attackers to cause a denial of service via a direct request without arguments.
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Analysis
by VulDB Data Team • 02/18/2025
The vulnerability described in CVE-2002-2309 represents a critical denial of service flaw affecting PHP versions 3.0 through 4.2.2 when operating within the Apache web server environment. This issue stems from improper termination behavior of the php.exe process, creating a condition where the application fails to properly handle requests that lack arguments or parameters. The flaw specifically manifests when PHP processes are invoked directly through Apache without proper argument handling, leading to resource exhaustion and system instability. This vulnerability directly impacts the availability of web services and can be exploited by remote attackers to disrupt normal operations.
The technical root cause of this vulnerability lies in the improper handling of process termination within the PHP interpreter when executing under Apache. When php.exe receives a request without arguments, the execution flow fails to properly conclude the process lifecycle, resulting in hanging processes that consume system resources indefinitely. This behavior creates a resource leak condition where multiple failed requests can accumulate, eventually exhausting available memory or process slots. The vulnerability operates at the application layer and specifically affects the Apache module interface where PHP is embedded, making it particularly dangerous in high-traffic environments where multiple concurrent requests may trigger the flaw. This issue is classified under CWE-400 as an Uncontrolled Resource Consumption vulnerability, which falls within the broader category of denial of service conditions.
The operational impact of CVE-2002-2309 extends beyond simple service disruption to potentially compromise entire web server operations. Remote attackers can exploit this vulnerability by sending crafted requests to the PHP interpreter without arguments, causing php.exe processes to remain active and consume system resources. This can lead to cascading failures where legitimate requests are denied service due to resource exhaustion, effectively rendering the web application unavailable to genuine users. The vulnerability is particularly dangerous because it requires minimal effort to exploit and can be automated, making it a preferred target for malicious actors seeking to disrupt web services. The flaw can be mapped to ATT&CK technique T1499.004, which describes the use of resource exhaustion attacks to cause denial of service conditions.
Mitigation strategies for this vulnerability require immediate action to address the underlying PHP version exposure. The primary solution involves upgrading to PHP versions 4.2.3 or later, where this specific termination issue has been resolved through improved process handling and resource management. System administrators should implement proper patch management procedures to ensure all PHP installations are updated to secure versions. Additionally, web server configurations should be reviewed to minimize direct exposure of php.exe to external requests, and input validation should be strengthened to prevent malformed requests from reaching the PHP interpreter. Network-level protections such as rate limiting and request filtering can provide additional defense-in-depth measures. Organizations should also implement monitoring solutions to detect unusual resource consumption patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper process lifecycle management in web application environments and highlights the need for comprehensive security testing of application server components.