CVE-2021-24281 in Redirection for Contact Form 7 Plugin
Summary
by MITRE • 05/14/2021
In the Redirection for Contact Form 7 WordPress plugin before 2.3.4, any authenticated user, such as a subscriber, could use the delete_action_post AJAX action to delete any post on a target site.
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Analysis
by VulDB Data Team • 05/16/2021
The vulnerability CVE-2021-24281 affects the Redirection for Contact Form 7 WordPress plugin, specifically versions prior to 2.3.4, presenting a critical access control flaw that allows authenticated users to perform unauthorized post deletion operations. This issue stems from inadequate input validation and permission checking within the plugin's AJAX handling mechanism, specifically the delete_action_post endpoint that processes administrative actions without proper authorization verification. The flaw exists in the plugin's core functionality where it fails to validate whether the requesting user has sufficient privileges to delete the targeted post, creating a path for privilege escalation attacks.
The technical implementation of this vulnerability resides in the plugin's AJAX action handling where the delete_action_post function processes deletion requests without performing adequate user role verification or post ownership checks. An authenticated user with minimal privileges such as a subscriber account can exploit this weakness by crafting malicious AJAX requests that target specific post IDs, effectively bypassing WordPress's standard permission model. This vulnerability directly maps to CWE-284 Access Control Flaw, which encompasses insufficient access control mechanisms that allow unauthorized users to perform privileged operations. The flaw represents a classic case of inadequate authorization checks where the system assumes that authenticated users can perform all operations without proper role-based validation.
The operational impact of this vulnerability extends beyond simple data loss, as it enables attackers to manipulate the target website's content in ways that can disrupt business operations, compromise user data, or serve as a stepping stone for further attacks. A malicious subscriber could delete important posts, pages, or contact form entries, potentially causing service disruption or data integrity issues that could affect customer relationships. The vulnerability also creates opportunities for attackers to establish persistence or conduct more sophisticated attacks by removing evidence of their activities. According to ATT&CK framework, this vulnerability aligns with T1078 Valid Accounts and T1485 Data Destruction techniques, as it allows attackers to leverage legitimate user accounts to perform destructive operations.
Mitigation strategies for this vulnerability require immediate plugin updates to version 2.3.4 or later, which implements proper access control checks and input validation. Administrators should also review user roles and permissions to ensure that only trusted administrators have access to potentially destructive functions. Network monitoring should be enhanced to detect unusual AJAX request patterns, particularly those targeting post deletion endpoints. Security hardening measures including implementing rate limiting for AJAX requests, using CAPTCHA mechanisms, and employing Web Application Firewalls can provide additional defense layers. Regular security audits of WordPress plugins and core systems remain essential for identifying similar access control weaknesses. Organizations should also implement proper incident response procedures to quickly detect and respond to unauthorized deletion activities, ensuring that any compromise is contained and investigated promptly. The vulnerability serves as a reminder of the critical importance of proper access control implementation in web applications and the potential for seemingly minor flaws to create significant security risks.