CVE-2009-3307 in FSphp
Summary
by MITRE
Multiple PHP remote file inclusion vulnerabilities in FSphp 0.2.1 allow remote attackers to execute arbitrary PHP code via a URL in the FSPHP_LIB parameter to (1) FSphp.php, (2) navigation.php, and (3) pathwrite.php in lib/.
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Analysis
by VulDB Data Team • 01/22/2025
The vulnerability identified as CVE-2009-3307 represents a critical remote code execution flaw affecting FSphp version 0.2.1, specifically targeting three core files within the application's library directory. This vulnerability stems from improper input validation and sanitization mechanisms that fail to properly restrict user-supplied data when processing file inclusion operations. The affected parameters in FSphp.php, navigation.php, and pathwrite.php within the lib/ directory accept URL values through the FSPHP_LIB parameter, creating an avenue for malicious actors to inject and execute arbitrary PHP code on the target system. The flaw directly corresponds to CWE-94, which describes the execution of code in a context where the code is not trusted, specifically manifesting as improper input validation in web applications.
The technical exploitation of this vulnerability occurs when an attacker supplies a malicious URL through the FSPHP_LIB parameter, which is then processed by the vulnerable PHP scripts without adequate sanitization or validation. The affected files demonstrate a classic remote file inclusion vulnerability where the application dynamically includes files based on user input, allowing attackers to specify external URLs that point to malicious PHP scripts hosted on remote servers. This creates a scenario where the web server will execute the malicious code as part of the normal application flow, effectively granting remote attackers complete control over the compromised system. The vulnerability is particularly dangerous because it operates at the application level and can be exploited without requiring authentication or specialized privileges, making it a prime target for automated attacks.
The operational impact of this vulnerability extends beyond simple code execution to encompass full system compromise and potential data exfiltration. Attackers can leverage this vulnerability to establish persistent backdoors, escalate privileges, and access sensitive system information or user data stored within the application. The remote nature of the exploit means that attackers can target vulnerable systems from anywhere on the internet, making this vulnerability particularly attractive for large-scale automated attacks. Organizations running FSphp 0.2.1 are at significant risk of unauthorized access, data breaches, and potential use as a stepping stone for further network infiltration. The vulnerability's classification under ATT&CK technique T1190 indicates it can be used for initial access and persistence within target environments, while T1059 demonstrates the execution capabilities available to attackers once the vulnerability is exploited.
Mitigation strategies for CVE-2009-3307 require immediate action to address the root cause through proper input validation and sanitization mechanisms. Organizations should implement strict parameter validation that rejects any input containing URLs or external references when processing file inclusion operations. The most effective immediate solution involves updating to a patched version of FSphp that addresses the vulnerability, as the original version contains fundamental design flaws that cannot be adequately secured through configuration changes alone. Security measures should include disabling remote file inclusion functionality entirely, implementing proper input filtering using allowlists of approved values, and configuring web application firewalls to monitor and block suspicious URL patterns. Additionally, organizations should conduct comprehensive security audits of their PHP applications to identify similar vulnerabilities, implement proper access controls, and establish monitoring protocols to detect potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of secure coding practices and proper input validation in preventing remote code execution attacks that can compromise entire systems.