WordPress 3.8.1 / 3.8.2 / 4.2.2 Cross Site Request Forgery
Posted on 09 August 2015
Details ================ Software: WordPress Version: 3.8.1,3.8.2,4.2.2 Homepage: http://wordpress.org/ Advisory report: https://security.dxw.com/advisories/comment-form-csrf-allows-admin-impersonation-via-comments-in-wordpress-4-2-2/ CVE: Awaiting assignment CVSS: 4.3 (Medium; AV:N/AC:M/Au:N/C:N/I:P/A:N) Description ================ Comment form CSRF in WordPress 4.2.2 allows admin impersonation via comments Vulnerability ================ When posting comments,WordPress does not require a nonce value (unless posting unfiltered HTML). This means that an attacker can force a logged-in user to post arbitrary comments. For this to happen, the logged-in user would have to be tricked into clicking on a link controlled by the attacker. It is easy to make these links very convincing. The line which verifies the nonce when using unfiltered HTML is line 154 of wp-comments-post.php. EDIT: this issue has been known about since 2009, but it appears that no fix is planned https://core.trac.wordpress.org/ticket/10931 Proof of concept ================ Log in, visit an URL containing the following (replacing localhost as appropriate, replacing 1 with the ID of a post), click submit: <form method="POST" action="http://localhost/wp-comments-post.php"> <input type="text" name="comment_post_ID" value="1"> <input type="text" name="comment" value="UH OH"> <input type="submit"> </form> (In a real attack the form can be made to auto-submit using Javascript) Mitigations ================ Disable comments until a new version is released that fixes this bug 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@dxw.com to acknowledge this report if you received it via a third party (for example, plugins@wordpress.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 ================ 2009-10-19: Ticket raised by mtdewvirus 2014-03-20: Discovered independently by dxw 2015-07-14: Reported to security@wordpress.org 2015-07-14: Requested CVE 2015-07-17: Response from nikolay@automattic.com 2015-08-05: Published Discovered by dxw: ================ Tom Adams Please visit security.dxw.com for more information.
