CVE-2007-1908 in PHP121 Instant Messenger
Summary
by MITRE
PHP file inclusion vulnerability in php121db.php in PHP121 Instant Messenger 2.2 allows remote attackers to execute arbitrary PHP code via a UNC share pathname or a local file pathname in the php121dir parameter, which is accessed by the file_exists function.
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Analysis
by VulDB Data Team • 09/04/2024
The vulnerability identified as CVE-2007-1908 represents a critical server-side include vulnerability affecting PHP121 Instant Messenger version 2.2. This flaw exists within the php121db.php script where user-supplied input is improperly handled, creating an opportunity for remote code execution through maliciously crafted file path parameters. The vulnerability specifically targets the php121dir parameter which is processed by the file_exists function, a common PHP function used to determine if a file or directory exists. When an attacker provides a specially crafted UNC share pathname or local file pathname, the application fails to properly validate or sanitize this input before using it in file system operations. This represents a classic path traversal and file inclusion vulnerability that falls under CWE-98, which describes improper control of resource identifiers, and specifically aligns with CWE-22, which covers improper limitation of a pathname to a restricted directory. The vulnerability demonstrates a fundamental flaw in input validation and sanitization practices within the application's codebase, where user-controllable data directly influences file system operations without adequate security controls.
The operational impact of this vulnerability extends far beyond simple data exposure, as it enables full remote code execution capabilities for attackers who can successfully exploit this weakness. When an attacker successfully manipulates the php121dir parameter through a UNC share path or local file path, they can potentially execute arbitrary PHP code on the target server with the privileges of the web application. This creates a severe risk for system compromise, as attackers can upload malicious files, establish backdoors, or perform further reconnaissance within the network. The attack vector leverages the file_exists function's behavior when processing UNC paths, which can cause the application to attempt to access remote network shares or local files that the attacker controls. This vulnerability directly maps to ATT&CK technique T1190, which covers exploit for lateral movement through remote service access, and T1059, which covers command and scripting interpreter for executing malicious code. The implications are particularly severe in environments where the web application runs with elevated privileges or where the server hosts sensitive data.
Mitigation strategies for this vulnerability must address both the immediate code-level issues and broader architectural security concerns. The primary remediation involves implementing strict input validation and sanitization for all user-supplied parameters, particularly those used in file system operations. The application should reject or properly encode any input containing UNC path indicators or suspicious file path patterns, and should implement a whitelist approach for acceptable file paths rather than allowing arbitrary user input to dictate file system access. Additionally, the application should avoid using user-supplied data directly in file_exists or similar functions without proper validation. Organizations should also implement network segmentation and access controls to limit the impact of potential exploitation, while ensuring that the web application runs with minimal necessary privileges. Regular security audits and code reviews should focus on identifying similar patterns where user input directly influences file system operations, as this vulnerability type commonly appears in legacy applications that lack modern security controls. The fix should also include implementing proper error handling to prevent information disclosure that might occur during failed file access attempts, as this could provide attackers with additional reconnaissance capabilities.