CVE-2021-4344 in Frontend File Manager Plugin
Summary
by MITRE • 06/07/2023
The Frontend File Manager plugin for WordPress is vulnerable to Privilege Escalation in versions up to, and including, 18.2. This is due to lacking mishandling the use of user IDs that is accessible by the visitor. This makes it possible for unauthenticated or authenticated attackers to access the information and privileges of other users, including 'guest users', in their own category (authenticated, or unauthenticated guests).
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Analysis
by VulDB Data Team • 07/05/2023
The Frontend File Manager plugin for WordPress presents a critical privilege escalation vulnerability identified as CVE-2021-4344 affecting versions up to and including 18.2. This vulnerability stems from improper handling of user identification mechanisms within the plugin's architecture, creating a fundamental security flaw that undermines the intended access control measures. The flaw allows attackers to manipulate user ID parameters in a manner that bypasses normal authentication and authorization boundaries, enabling unauthorized access to resources that should be restricted to specific user roles or categories.
The technical implementation of this vulnerability resides in the plugin's failure to properly validate and sanitize user ID inputs during file management operations. When visitors interact with the frontend file manager, the system incorrectly processes user identifiers, allowing an attacker to submit crafted user ID values that correspond to other users within the same category. This misconfiguration creates a path for privilege escalation where unauthenticated users can potentially access guest user accounts or authenticated users' resources, effectively breaking down the security isolation that should exist between different user roles. The vulnerability operates at the application layer and leverages weak input validation practices that are commonly associated with CWE-20, which represents "Improper Input Validation" in the Common Weakness Enumeration catalog.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to gain unauthorized access to sensitive files and potentially manipulate the file system through the compromised user accounts. Attackers can exploit this weakness to access other users' uploaded files, modify file permissions, or even execute malicious code if the file manager allows script execution. The vulnerability affects both authenticated and unauthenticated users, making it particularly dangerous as it can be exploited by anyone who can access the frontend file manager interface. This creates a significant risk for WordPress installations where the plugin is active, as it essentially allows attackers to assume the identity and privileges of other users within the same user category, potentially leading to full system compromise if the compromised accounts have elevated permissions.
Mitigation strategies for this vulnerability require immediate attention from WordPress administrators, including updating to the patched version of the Frontend File Manager plugin as soon as possible. The vulnerability demonstrates the critical importance of proper access control implementation and input validation within web applications, aligning with ATT&CK technique T1078 for Valid Accounts and T1484 for Privilege Escalation. Organizations should implement additional monitoring of file manager activities and user ID parameter usage to detect potential exploitation attempts. Security measures should also include restricting access to the frontend file manager interface to authenticated users only and implementing proper role-based access controls that prevent cross-user privilege escalation. The vulnerability highlights the necessity of thorough security testing for plugins and themes, particularly those handling file operations and user access controls, as outlined in the OWASP Top Ten security risks and the NIST Cybersecurity Framework guidelines for application security.