CVE-2016-6613 in phpMyAdmin
Summary
by MITRE
An issue was discovered in phpMyAdmin. A user can specially craft a symlink on disk, to a file which phpMyAdmin is permitted to read but the user is not, which phpMyAdmin will then expose to the user. All 4.6.x versions (prior to 4.6.4), 4.4.x versions (prior to 4.4.15.8), and 4.0.x versions (prior to 4.0.10.17) are affected.
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Analysis
by VulDB Data Team • 10/05/2022
This vulnerability in phpMyAdmin represents a critical access control flaw that enables unauthorized data exposure through symbolic link manipulation. The issue stems from improper handling of symbolic links within the application's file access mechanisms, allowing malicious users to create crafted symlinks that point to sensitive files outside of the intended access scope. When phpMyAdmin processes these symlinks, it follows the link traversal without proper authorization checks, effectively bypassing the normal access controls that should prevent users from reading files they do not have explicit permissions to access. This vulnerability specifically affects versions across multiple release branches including 4.6.x prior to 4.6.4, 4.4.x prior to 4.4.15.8, and 4.0.x prior to 4.0.10.17, indicating a widespread impact across the phpMyAdmin codebase.
The technical exploitation of this vulnerability involves creating a symbolic link that references a file within the web root or accessible directory structure, where the link points to a sensitive system file or database file that the application has read permissions for but the user does not. When phpMyAdmin encounters this symlink during file operations, it follows the link and displays the contents of the target file to the authenticated user, effectively providing a means to access restricted system information. This flaw operates at the intersection of file system traversal and access control enforcement, where the application's security model fails to properly validate the target of symbolic links against the user's authorization context. The vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and CWE-23 (Relative Path Traversal) classifications, as it allows for unauthorized path traversal through symbolic link manipulation.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks. An attacker who can create symbolic links in the phpMyAdmin environment can gain access to database configuration files, system user credentials, application logs, and other sensitive files that might contain authentication tokens, encryption keys, or other critical information. This access could facilitate further compromise of the system, including potential privilege escalation or lateral movement within the network infrastructure. The vulnerability represents a significant risk in environments where phpMyAdmin is deployed with elevated privileges or where it has access to sensitive system files through its configuration. Attackers could leverage this flaw to extract database connection strings, application secrets, and other information that could be used for additional attacks against the underlying database systems or the broader infrastructure.
Organizations should implement immediate mitigations including updating to the patched versions of phpMyAdmin, specifically versions 4.6.4, 4.4.15.8, and 4.0.10.17, which contain the necessary fixes to properly validate symbolic links and prevent unauthorized file access. Additional security measures should include restricting the ability to create symbolic links in phpMyAdmin's working directories, implementing proper file system access controls, and monitoring for unusual file system activities that might indicate symlink creation attempts. The vulnerability demonstrates the importance of proper input validation and access control enforcement in web applications, particularly when dealing with file system operations. Organizations should also consider implementing network-based detection measures to identify potential exploitation attempts and ensure that phpMyAdmin installations are properly configured with minimal necessary privileges to reduce the potential impact of such vulnerabilities. This issue highlights the broader ATT&CK tactic of privilege escalation and credential access through improper access control mechanisms, emphasizing the need for comprehensive security controls around file system operations in web applications.