Arbitrary File Upload
Advanced Custom Fields and Advanced Custom Fields Pro have 2+ million installs according to wordpress.org. Versions older than 5.12.3 allow unauthenticated users to upload arbitrary files if there is a frontend form available. This vulnerability was introduced in the 5.0 rewrite and did not exist prior to that release.
Fortunately by default WordPress does not allow uploading of .php files so this vulnerability is not easily wormable, but there are many other file types that can be uploaded that can be then used with another exploit to execute code or used in a phishing attack to get a user to download and execute a resource from a “trusted” site.
No exploit code is being released at this time.
- 7/11/2022 Contacted developer
- 7/12/2022 Disclosed vulnerability
- 7/13/2022 Patch received from developer for testing
- 7/14/2022 Fix deployed to GitHub and pushed to wordpress.org plugin repository
Elementor Page Builder versions less than 1.8 contain a major security issue that allows logged in users (not just admin) unrestricted access to the Elementor specific backend functions. This allows unrestricted importing/exporting of content and potentially complete site compromise. The WordPress.org repository claims there are over 300,000 active installations.
If you are running an older version, upgrade immediately. The Elementor team did not appear to be planning any disclosure or notification and the only indication in the changelog of any potential issues is “Fix! – Patched nonce validation for all library actions” along with additional nonce related fixes over the next few days to deal with bugs related to this patching.
Due to the large number of installs I will not describe the exact steps to exploit these methods. Many of the AJAX actions are accessible to any logged in user. Some of the actions are protected with the ‘elementor-editing’ nonce, unfortunately that was leaked to any logged in user via the WordPress heartbeat.
- 10/17/2017 Sent initial contact inquiry
- 10/18/2017 Received response and disclosure sent
- 10/26/2017 Followup message sent to check status
- 11/7/2017 Version 1.8.0 released
In the quest for a good solution to allow different groups to control their own content on a WordPress site, I came across the Advanced Access Manager plugin. During a standard cursory investigation of the code I discovered that any logged in user could execute any of the AJAX actions without proper authorization.
As a normal subscriber account, I was able to give myself administrator privileges on the site and do much more.
The wordpress.org repository claims there are 50,000+ active installs of this plugin. If you are using a version <= 3.2.1, upgrade immediately.
The AJAX actions were protected only with the ‘aam_ajax’ nonce which could be leaked by passing in HTTP POST variable ‘action=aam’. The following function is called from the ‘admin_print_scripts’ action, which in turn calls the printLocalization() function which includes the nonce.
Unrestricted AJAX Actions
Once you have acquired a valid nonce, as a logged in user you can then call the ‘aam’ AJAX action.
Which will allow you to call any function in the ‘AAM_Backend_View’ class or in any class that begins with ‘AAM_Backend_’
Almost every action taken by this plugin goes through this function, so anything that an administrator can do is now accessible to anyone with basic login credentials.
- 5/11/2016 8:25pm Submitted contact form for initial contact
- 5/12/2016 5:34am Response received
- 5/12/2016 8:10am Initial Disclosure
- 6/15/2016 GitHub repository updated
- 6/20/2016 Version 3.2.2 released