Compliance Impact

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Executive Summary

The User Registration & Membership plugin for WordPress has a vulnerability in versions up to and including 5.1.2 that allows authentication bypass. This occurs because the 'register_member' function incorrectly handles authentication, enabling unauthenticated attackers to log in as a newly registered user who has the 'urm_user_just_created' user meta set.

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Impact Analysis

This vulnerability can allow an unauthenticated attacker to gain access to the site by logging in as a newly registered user without proper authentication. This can lead to unauthorized access, potentially compromising the confidentiality, integrity, and availability of the affected WordPress site.

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Detection Guidance

[{'type': 'paragraph', 'content': "This vulnerability involves an authentication bypass in the 'register_member' function of the User Registration & Membership WordPress plugin, allowing unauthenticated attackers to log in as newly registered users with the 'urm_user_just_created' user meta set."}, {'type': 'paragraph', 'content': 'To detect this vulnerability on your system, you can check if your WordPress installation is running the User Registration & Membership plugin version 5.1.2 or earlier.'}, {'type': 'paragraph', 'content': "You can also monitor for suspicious POST requests to the AJAX action 'register_member' that might be attempting to exploit this bypass."}, {'type': 'list_item', 'content': "Use WP-CLI or database queries to identify users with the 'urm_user_just_created' meta key set, which indicates newly registered users potentially created via this vulnerability."}, {'type': 'list_item', 'content': 'Example WP-CLI command to find such users: wp user meta get <user_id> urm_user_just_created'}, {'type': 'list_item', 'content': "Example SQL query to find users with this meta key: SELECT user_id FROM wp_usermeta WHERE meta_key = 'urm_user_just_created';"}, {'type': 'list_item', 'content': "Monitor web server logs for POST requests to admin-ajax.php with the action parameter 'register_member' coming from unauthenticated sources."}] [1]

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Mitigation Strategies

[{'type': 'paragraph', 'content': 'The immediate mitigation step is to update the User Registration & Membership plugin to a version later than 5.1.2 where this authentication bypass vulnerability is fixed.'}, {'type': 'paragraph', 'content': "If an update is not immediately possible, consider disabling or restricting access to the 'register_member' AJAX action to authenticated users only, to prevent unauthenticated exploitation."}, {'type': 'paragraph', 'content': "Additionally, monitor and remove any suspicious users created with the 'urm_user_just_created' meta key."}, {'type': 'paragraph', 'content': "Implement web application firewall (WAF) rules to block or alert on suspicious POST requests targeting the 'register_member' AJAX endpoint."}] [1]

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