CVE-2021-24279 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, low level users, such as subscribers, could use the import_from_debug AJAX action to install any plugin from the WordPress repository.
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Analysis
by VulDB Data Team • 05/16/2021
The vulnerability CVE-2021-24279 affects the Redirection for Contact Form 7 WordPress plugin, specifically targeting versions prior to 2.3.4. This security flaw represents a critical privilege escalation issue that allows low-privilege users to execute arbitrary plugin installations on vulnerable WordPress sites. The vulnerability exists within the plugin's AJAX handling mechanism, specifically the import_from_debug action which was designed for debugging purposes but failed to properly validate user permissions. Attackers with subscriber-level access or similar low-privilege accounts can exploit this flaw to gain unauthorized control over the site's plugin ecosystem.
The technical implementation of this vulnerability stems from insufficient access control validation within the plugin's AJAX endpoint. The import_from_debug action was intended for developers to debug plugin configurations but was improperly secured, allowing any authenticated user regardless of their role to trigger the plugin installation process. This flaw directly violates the principle of least privilege and demonstrates poor input validation practices. The vulnerability can be classified under CWE-284 Access Control, specifically addressing inadequate permissions checks for privileged operations. The flaw enables attackers to install malicious plugins from the WordPress repository, potentially leading to complete site compromise through the installation of backdoors, malware, or other harmful components.
The operational impact of this vulnerability extends beyond simple privilege escalation, creating a significant attack surface for malicious actors. Low-privilege users who gain access to the WordPress site can leverage this vulnerability to install plugins that may contain malicious code, leading to persistent threats that can compromise the entire website infrastructure. This vulnerability directly aligns with ATT&CK technique T1105 Command and Scripting Interpreter, as attackers can use the legitimate plugin installation mechanism to execute malicious code. The attack chain typically involves initial access through compromised credentials, followed by exploitation of this vulnerability to escalate privileges and install malicious plugins that can persist across site reboots and user sessions.
Mitigation strategies for CVE-2021-24279 primarily focus on immediate plugin updates to version 2.3.4 or later, which contains proper access controls and permission validation. Organizations should also implement network-level restrictions to limit access to AJAX endpoints and consider role-based access controls that prevent low-privilege users from accessing debugging features. Security monitoring should include detection of unauthorized plugin installations and unusual AJAX activity patterns. The vulnerability highlights the importance of proper input validation and access control implementation, particularly for debugging features that should never be exposed to unprivileged users. Regular security audits of WordPress plugins should include verification of access controls and permission mechanisms to prevent similar issues from occurring in other components of the WordPress ecosystem.