CVE-2019-6703 in Calmar Webmedia Total Donations Plugin
Summary
by MITRE
Incorrect access control in migla_ajax_functions.php in the Calmar Webmedia Total Donations plugin through 2.0.5 for WordPress allows unauthenticated attackers to update arbitrary WordPress option values, leading to site takeover. These attackers can send requests to wp-admin/admin-ajax.php to call the miglaA_update_me action to change arbitrary options on affected sites. This can be used to enable new user registration and set the default role for new users to Administrator.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 05/06/2020
The vulnerability identified as CVE-2019-6703 represents a critical access control flaw within the Calmar Webmedia Total Donations WordPress plugin, specifically affecting versions through 2.0.5. This issue stems from insufficient authentication checks in the migla_ajax_functions.php file, which processes AJAX requests through the WordPress admin-ajax.php endpoint. The flaw allows unauthenticated attackers to exploit a designated action hook named miglaA_update_me, which is intended for legitimate administrative operations but lacks proper authorization verification. The vulnerability operates at the intersection of weak input validation and improper privilege enforcement, creating a pathway for malicious actors to manipulate core WordPress configuration settings without requiring any valid credentials or administrative privileges.
The technical implementation of this vulnerability exploits the plugin's reliance on AJAX for administrative functions while failing to implement adequate authentication mechanisms. When an attacker sends a crafted request to the wp-admin/admin-ajax.php endpoint with the specific action parameter set to miglaA_update_me, the plugin processes the request without verifying the user's authentication status or administrative privileges. This design flaw directly violates the principle of least privilege and demonstrates a classic example of insecure direct object reference vulnerability, where the system fails to validate whether the requesting entity has appropriate authorization to perform the requested operation. The vulnerability is further exacerbated by the fact that the affected plugin operates within the WordPress ecosystem, where the compromised option values can directly influence user registration and role assignment mechanisms, creating a direct path to privilege escalation.
The operational impact of this vulnerability extends far beyond simple data modification, as it provides attackers with the capability to fundamentally alter the security posture of compromised WordPress installations. By leveraging this flaw, attackers can enable new user registration and subsequently set the default role for new users to Administrator, effectively creating backdoor accounts that persist even after the initial exploitation attempt. This capability aligns with the attack pattern described in the MITRE ATT&CK framework under the T1133: External Remote Services technique, where attackers establish persistent access through compromised administrative functions. The vulnerability also maps to CWE-284: Improper Access Control, which specifically addresses insufficient access control mechanisms that allow unauthorized users to perform privileged operations. The implications of such a flaw are particularly severe because WordPress sites often serve as critical business platforms, and the ability to escalate privileges through a simple unauthenticated request can result in complete system compromise.
Mitigation strategies for this vulnerability require immediate action from affected site administrators, beginning with the mandatory upgrade to the patched version of the Calmar Webmedia Total Donations plugin. The recommended approach aligns with industry best practices for vulnerability remediation and follows the principle of defense in depth. Organizations should also implement network-level controls such as firewall rules that restrict access to wp-admin/admin-ajax.php endpoint from unauthorized sources, though this approach must be carefully balanced to avoid disrupting legitimate plugin functionality. Additionally, implementing robust monitoring and logging of AJAX requests can help detect exploitation attempts, while regular security audits of WordPress plugins should include verification of authentication mechanisms and access control implementations. The vulnerability serves as a reminder of the critical importance of proper authentication checks in web applications, particularly those that handle administrative functions, and underscores the necessity of maintaining up-to-date security patches across all application components.