CVE-2009-2353 in eAccelerator
Summary
by MITRE
encoder.php in eAccelerator allows remote attackers to execute arbitrary code by copying a local executable file to a location under the web root via the -o option, and then making a direct request to this file, related to upload of image files.
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Analysis
by VulDB Data Team • 08/12/2021
The vulnerability identified as CVE-2009-2353 affects eAccelerator, a PHP opcode cache and optimizer that was widely used to improve PHP application performance. This flaw resides in the encoder.php component of eAccelerator and represents a critical security weakness that enables remote code execution through a specific file handling mechanism. The vulnerability stems from inadequate input validation and improper file permission handling within the upload and encoding process, creating a pathway for attackers to escalate privileges and execute malicious code on vulnerable systems.
The technical exploitation of this vulnerability involves a sophisticated attack vector that leverages the -o option in eAccelerator's encoder.php script. Attackers can manipulate the file upload process to copy a local executable file to a web-accessible directory, effectively bypassing normal security restrictions. This occurs because the encoder.php script fails to properly validate or sanitize the output path specified by the -o parameter, allowing attackers to specify arbitrary locations within the web root. When the malicious file is subsequently accessed through a direct HTTP request, the web server executes the payload, granting the attacker full control over the affected system. This vulnerability is particularly dangerous because it combines elements of file upload exploitation with privilege escalation, creating a multi-layered attack approach that can bypass traditional security controls.
The operational impact of CVE-2009-2353 extends far beyond simple code execution, as it fundamentally compromises the security posture of affected systems. Organizations running vulnerable eAccelerator installations face the risk of complete system compromise, data theft, and potential lateral movement within their network infrastructure. The vulnerability is particularly concerning in web hosting environments where multiple tenants share the same infrastructure, as a single compromised site can potentially affect all users on that server. The attack requires minimal privileges to execute and can be automated, making it attractive to both script kiddies and sophisticated attackers. This vulnerability directly relates to CWE-22, which describes improper limitation of a pathname to a restricted directory, and CWE-74, which covers injection flaws, particularly in the context of file operations and path traversal attacks. The exploitability of this vulnerability also aligns with techniques described in the MITRE ATT&CK framework under T1059 for command and scripting interpreter and T1078 for valid accounts, as attackers can leverage legitimate system access to execute malicious payloads.
Mitigation strategies for CVE-2009-2353 require immediate action to address the root cause of the vulnerability. Organizations should prioritize updating to patched versions of eAccelerator or migrating to more modern opcode caching solutions such as OPcache that are actively maintained and supported. The immediate removal of vulnerable encoder.php scripts from web-accessible directories provides temporary protection, though this approach is not recommended as a long-term solution. Network segmentation and proper file permission controls should be implemented to limit the impact of potential exploitation, ensuring that uploaded files are stored outside of web root directories and that appropriate access controls are enforced. Additionally, implementing web application firewalls and intrusion detection systems can help detect and prevent exploitation attempts. Regular security audits and vulnerability assessments should be conducted to identify and remediate similar weaknesses in other components of the application stack, while maintaining up-to-date security patches for all server software components to prevent similar vulnerabilities from emerging in the future.