WP User Frontend < 2.3.11 - Arbitrary File Upload

2016-02-08 00:00
Panagiotis Vagenas

Strategic Overview

Status
Patched in 2.3.11
Affected Plugin
User Frontend – Membership, User Registration, User Profile, User Directory & Content Restriction with Frontend Post Submission
Affected Version
< 2.3.11
CVSS
9.8Critical
Weakness type
CWE-434 · Unrestricted Upload of File with Dangerous Type
CVE
CVE pending
View all User Frontend – Membership, User Registration, User Profile, User Directory & Content Restriction with Frontend Post Submission vulnerabilities

At a glance

This record tracks a critical-severity Unrestricted Upload of File with Dangerous Type vulnerability in the User Frontend WordPress plugin, affecting versions < 2.3.11. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 2.3.11; sites on affected versions should update now. Disclosed February 2016, reported by Panagiotis Vagenas.

Vulnerability Overview

The WP User Frontend plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the 'wpuf_file_upload' and 'wpuf_insert_image' AJAX actions in versions before 2.3.11. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected sites server which may make remote code execution possible.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-434: Unrestricted Upload of File with Dangerous Type

User Frontend < 2.3.11 carries this weakness at wpuf_file_upload, and reaching it takes a caller who can reach the endpoint. An unrestricted file upload lets a caller store a file whose type or destination the application does not properly constrain.

If an uploaded file lands anywhere the server will execute, the flaw becomes remote code execution and the site should be treated as fully compromised. For User Frontend the fix is 2.3.11: builds < 2.3.11 are affected, anything from 2.3.11 onward is not.

Remediation

Update to version 2.3.11, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to User Frontend: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: User Frontend 2.3.11 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Alerts

External References

https://www.wordfence.com/threat-intel/vulnerabilities/id/8a2186c9-fa27-4d7d-be41-c82711c49334

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