CVE-2008-1614 in suPHP
Summary
by MITRE
suPHP before 0.6.3 allows local users to gain privileges via (1) a race condition that involves multiple symlink changes to point a file owned by a different user, or (2) a symlink to the directory of a different user, which is used to determine privileges.
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Analysis
by VulDB Data Team • 08/08/2019
The suPHP vulnerability identified as CVE-2008-1614 represents a critical privilege escalation flaw in the suPHP web server module version 0.6.2 and earlier. This vulnerability specifically targets the way suPHP handles file ownership and directory permissions when executing PHP scripts, creating exploitable conditions that allow local attackers to bypass intended security restrictions. The vulnerability stems from insufficient synchronization mechanisms and improper handling of symbolic links within the privilege management system, enabling attackers to manipulate file access controls through carefully crafted symlink operations.
The technical implementation of this vulnerability exploits two distinct but related race conditions within the suPHP execution environment. The first condition involves a race between multiple concurrent symlink operations that can be manipulated to redirect file access to unauthorized locations owned by different users. The second condition occurs when suPHP follows symbolic links to determine user privileges, allowing attackers to create malicious symlinks pointing to directories of other users. These race conditions are particularly dangerous because they exploit the timing window between file existence checks and actual file operations, a common pattern in Unix-like systems where such vulnerabilities are classified under CWE-367. The flaw essentially allows an attacker to manipulate the file system state during the privilege determination process, enabling unauthorized access to files and directories that should be restricted to specific user contexts.
The operational impact of this vulnerability is severe for web hosting environments that rely on suPHP for secure PHP execution. Attackers can leverage this flaw to escalate privileges from the web server user to other users on the same system, potentially gaining access to sensitive data, configuration files, and user accounts. This privilege escalation can lead to complete system compromise, data theft, and unauthorized modifications to web applications and system files. The vulnerability affects shared hosting environments where multiple users operate under different privileges, making it particularly dangerous in multi-tenant server configurations where security isolation is paramount. From an attack perspective, this vulnerability aligns with ATT&CK technique T1068 which involves exploiting local system privileges to gain unauthorized access to resources, and T1548.001 which covers privilege escalation through the use of system binaries with elevated privileges.
Mitigation strategies for this vulnerability require immediate patching of suPHP to version 0.6.3 or later, which implements proper synchronization mechanisms and improved symlink handling. System administrators should also implement additional security controls such as restricting symbolic link creation in critical directories, monitoring for suspicious symlink operations, and ensuring proper file system permissions are maintained. The vulnerability highlights the importance of proper race condition handling in security-critical code and underscores the need for careful consideration of atomic operations in privilege management systems. Organizations should also review their web server configurations and implement monitoring for unauthorized privilege escalation attempts, as the vulnerability can be exploited without requiring remote network access, making it particularly insidious in environments where local system access is possible.