The following is writeup of how I dealt with a specific circumstance. I was up against a wordpress installation in one of my tests and luckily I already had editor level credentials. So I have to somehow obtain a shell. Remember that editor's do not have the ability to edit/add themes/plugins. So, aim was to run php using my editor privileges.
Solid Facts :§
- I can add html in the site using editor privileges (i.e unfiltered_html capability for editors).
- Nothing more valuable than the above point. (Later found some interesting places in dashboard where payloads work).
Methods which won't work :§
- Cannot steal cookies of administrator, since httponly flag is set on cookies.
- No dumb popups asking for password because that might create suspicion, we ain't dealing with skiddies.
- Solid patched wordpress with up-to-date plugins.
Methods which will :§
Resetting admin password. I wrote a sample POC which when run resets admin password to t3st.
User roles can be changed by admin in the interface, so again with some js-fu we can generate these requests to escalate our editor account to admin.
Admin can write php directly to themes and plugins, so something like this can be done.
Email address of the admin can also be changed instead of password, then password reset and boom.
Since I am lazy, I just created POC for the first one. Off all the above, I used the third one to write some file of the theme and I popped a hard shell. So the crisp till now is Even though wordpress doesn't allow editors to write php directly, we can do it in an indirect manner
Hold on folks, I know what you are thinking, for the above attacks to work, a loggedin admin has to visit an infected post/page. I will say not required. WHY?
Added advantages :§
A JS-payload entered in the title of a new post/page (by using editor obviously) gets executed right in the homepage of dashboard. WTF? WHERE?
Recently Published section in the dashboard shows the latest posts/pages, so payloads get executed there
Payload also gets executed in Revisions of that particular post/page.
Obviously the original page/post.
And in a flash I remembered two statements :§
- Privilege escalation
- Content is never displayed unfiltered in the admin
Reported these to wordpress and they classified these bugs as :
- Won't Fix
May be they are right, but then why different accounts for admin and editor when both can do same set of tasks ;)