The Advanced IP Blocker plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 8.13.13 The vulnerability exists because handle_login_action() performs no server-side check — via transient, session marker, or equivalent — that a requester completed step-1 password authentication before processing a step-2 TOTP submission for the POSTed user_id; compounding this, an error branch in the function unconditionally mints a fresh advaipbl-2fa-interim-{user_id} nonce and delivers it in a Location header to any unauthenticated caller, after which display_2fa_login_form_step_2() renders a valid advaipbl-2fa-verify-{user_id} nonce in HTML — both nonces computed against a fixed uid=0 empty-session context and therefore fully reusable by the attacker across subsequent requests. This makes it possible for unauthenticated attackers to bypass authentication entirely for any 2FA-enabled account, including administrators, by brute-forcing an unthrottled 6-digit TOTP code (no attempt counter, no account lockout, and no wp_login_failed firing) and receiving a fully authenticated session cookie via wp_set_auth_cookie without ever supplying the account password, resulting in complete site takeover. Exploitation requires only a known user_id for an account that has the plugins 2FA feature enabled.
Weakness
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
Potential Mitigations
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/114.html
- https://cwe.mitre.org/data/definitions/115.html
- https://cwe.mitre.org/data/definitions/151.html
- https://cwe.mitre.org/data/definitions/194.html
- https://cwe.mitre.org/data/definitions/22.html
- https://cwe.mitre.org/data/definitions/57.html
- https://cwe.mitre.org/data/definitions/593.html
- https://cwe.mitre.org/data/definitions/633.html
- https://cwe.mitre.org/data/definitions/650.html
- https://cwe.mitre.org/data/definitions/94.html
References
- https://plugins.trac.wordpress.org/browser/advanced-ip-blocker/tags/8.13.13/includes/class-advaipbl-2fa-manager.php#L71
- https://plugins.trac.wordpress.org/browser/advanced-ip-blocker/tags/8.13.13/includes/class-advaipbl-main.php#L519
- https://plugins.trac.wordpress.org/browser/advanced-ip-blocker/tags/8.13.13/includes/class-advaipbl-main.php#L6875
- https://plugins.trac.wordpress.org/browser/advanced-ip-blocker/tags/8.13.13/includes/class-advaipbl-main.php#L6912
- https://plugins.trac.wordpress.org/browser/advanced-ip-blocker/tags/8.13.13/includes/class-advaipbl-main.php#L7022
- https://plugins.trac.wordpress.org/changeset/3725139/advanced-ip-blocker/trunk/includes/class-advaipbl-main.php
- https://www.wordfence.com/threat-intel/vulnerabilities/id/d080845b-6814-4b10-a3ab-1f5aa1d09132?source=cve