Freshmail for WordPress <= 1.5.8 - shortcode.php SQL Injection

There is a SQL Injection vulnerability available for collaborators (or higher privileged users) for webs with freshmail plugin installed. The SQL Injection is located in the attribute “id” of the inserted shortcode [FM_form id=“N”]. The shortcode attribute “id” is not sanitized before inserting it in a SQL query. A collaborator can insert shortcodes when he/she is editing a new post or page and can preview the results (no administrator approval needed), launching this SQL Injection.

PoC

1. As collaborator, start a new post. 2. Insert the shortcode [FM_form id=‘1" and substr(user(),1,1)="b’] 3. Click preview. 4. If the form is shown, the statement is true, if not, false.