CVE-2008-6731 in FlexPHPLink
Summary
by MITRE
Unrestricted file upload vulnerability in submitlink.php in FlexPHPLink Pro 0.0.7 allows remote attackers to execute arbitrary PHP code by uploading a file with an executable extension, then accessing it via a direct request to the renamed file in linkphoto/.
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Analysis
by VulDB Data Team • 11/21/2024
The vulnerability described in CVE-2008-6731 represents a critical unrestricted file upload flaw in FlexPHPLink Pro version 0.0.7 that fundamentally compromises the security posture of affected systems. This vulnerability exists within the submitlink.php script which processes user-submitted content without proper validation or sanitization of file uploads. The flaw specifically allows remote attackers to bypass security controls by uploading malicious files with executable extensions such as .php, .phtml, or other server-executable formats directly to the linkphoto/ directory where the application stores uploaded content.
The technical exploitation of this vulnerability follows a straightforward yet dangerous methodology where attackers first identify the upload endpoint in submitlink.php, then craft malicious files with PHP code embedded within them. Once uploaded successfully, these files can be executed by the web server when accessed through direct URL requests to the renamed files within the linkphoto/ directory structure. This creates an immediate code execution capability for attackers who can leverage this to gain full control over the affected web server, potentially leading to data breaches, system compromise, or further network infiltration.
From an operational impact perspective, this vulnerability exposes organizations running FlexPHPLink Pro 0.0.7 to severe security risks including arbitrary code execution, remote command execution, and potential full system compromise. The vulnerability directly maps to CWE-434 which describes "Unrestricted Upload of File with Dangerous Type" and aligns with ATT&CK technique T1190 for "Exploit Public-Facing Application" and T1059.007 for "Command and Scripting Interpreter: PowerShell". The implications extend beyond immediate code execution to include persistent backdoor establishment, data exfiltration, and lateral movement within compromised networks.
Organizations should implement immediate mitigations including input validation and sanitization of all file uploads, restricting file types to only allow safe extensions, implementing proper file name randomization or renaming during upload processes, and configuring web server permissions to prevent execution of uploaded files in web-accessible directories. The vulnerability demonstrates the critical importance of secure file upload handling and proper application security controls. Additionally, organizations should consider implementing web application firewalls, regular security assessments, and comprehensive monitoring of upload directories for suspicious activity. The vulnerability also highlights the need for proper security testing including penetration testing and code review processes to identify and remediate similar issues in legacy applications before they can be exploited by threat actors.