W3 Total Cache <= 0.9.4.1 - Arbitrary File Upload

2016-09-26 00:00
SecuPress

Strategic Overview

Status
Patched in 0.9.5
Affected Plugin
W3 Total Cache
Affected Version
<= 0.9.4.1
CVSS
8.8High
Weakness type
CWE-434 · Unrestricted Upload of File with Dangerous Type
CVE
CVE pending
View all W3 Total Cache vulnerabilities

At a glance

This record tracks a high-severity Unrestricted Upload of File with Dangerous Type vulnerability in the W3 Total Cache WordPress plugin, affecting versions <= 0.9.4.1. It carries a CVSS score of 8.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). The issue is fixed in version 0.9.5; sites on affected versions should update now. Disclosed September 2016, reported by SecuPress.

Vulnerability Overview

The W3 Total Cache plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in versions up to, and including, 0.9.4.1. This makes it possible for authenticated 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 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

Reaching this weakness in W3 Total Cache <= 0.9.4.1 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 W3 Total Cache the fix is 0.9.5: builds <= 0.9.4.1 are affected, anything from 0.9.5 onward is not.

Remediation

Update to version 0.9.5, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to W3 Total Cache: 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: W3 Total Cache 0.9.5 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/c187ed25-6ba7-4a58-97df-5fea723d485a

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