CVE-2007-6459 in Anon Proxy Server
Summary
by MITRE
Anon Proxy Server 0.100, and probably 0.101, allows remote attackers to execute arbitrary commands via shell metacharacters in (1) the host parameter to diagdns.php, and (2) the host parameter and possibly (3) the port parameter to diagconnect.php, a different vulnerability than CVE-2007-6460.
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Analysis
by VulDB Data Team • 10/13/2024
The vulnerability described in CVE-2007-6459 represents a critical command injection flaw in Anon Proxy Server version 0.100 and potentially 0.101. This security weakness stems from inadequate input validation within the proxy server's diagnostic functionality, specifically affecting two distinct PHP scripts that handle network connectivity testing. The vulnerability exists in the way these scripts process user-supplied parameters without proper sanitization, creating an avenue for malicious actors to execute arbitrary system commands on the affected server. The affected scripts diagdns.php and diagconnect.php are designed to perform diagnostic functions such as DNS resolution and network connectivity testing, but they fail to properly validate or escape input parameters before using them in system calls.
The technical implementation of this vulnerability relies on the manipulation of shell metacharacters within the host parameter of diagdns.php and the host and potentially port parameters of diagconnect.php. When an attacker provides malicious input containing shell metacharacters such as semicolons, ampersands, or backticks, these characters are interpreted by the underlying operating system shell rather than being treated as literal string data. This allows attackers to append additional commands that execute with the privileges of the web server process, potentially enabling full system compromise. The vulnerability demonstrates poor input validation practices and highlights the dangerous combination of user-controllable input being directly passed to shell execution functions without proper sanitization or escaping mechanisms. This type of flaw directly maps to CWE-77, which describes improper neutralization of special elements used in a command shell, and represents a classic command injection vulnerability.
The operational impact of this vulnerability extends beyond simple remote code execution, as it provides attackers with significant control over the affected system. Successful exploitation could enable attackers to install malware, modify system files, steal sensitive data, or establish persistent backdoors. The vulnerability affects the proxy server's diagnostic functionality, which is typically accessible to any authenticated user or even unauthenticated users depending on the configuration. This creates a scenario where an attacker could potentially gain unauthorized access to network diagnostic capabilities and leverage them to perform reconnaissance activities or escalate privileges. The vulnerability also demonstrates the importance of secure coding practices in web applications, particularly when dealing with user input that may be passed to system-level operations. According to ATT&CK framework, this vulnerability corresponds to T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation, as the initial access through command injection can lead to further exploitation opportunities.
Mitigation strategies for this vulnerability require immediate implementation of input validation and sanitization measures across all affected scripts. Organizations should implement proper parameter validation that rejects or escapes special shell metacharacters before any input is processed. The recommended approach involves using whitelisting techniques to restrict input to known safe values or implementing proper escaping mechanisms that prevent shell interpretation of user-supplied data. Additionally, the affected proxy server versions should be updated to patched releases that address this vulnerability, or the diagnostic functionality should be disabled if not required. Network segmentation and access controls should be implemented to limit exposure of these vulnerable scripts to untrusted users. Regular security audits and code reviews should be conducted to identify similar patterns in other applications, as this vulnerability demonstrates the need for comprehensive input validation across all user-controllable parameters that may be passed to system commands. The vulnerability also underscores the importance of Principle of Least Privilege, where web server processes should run with minimal necessary privileges to limit the potential impact of such exploits.