CVE-2009-3890

WordPress Core <= 2.8.5 - Arbitrary File Upload

2009-12-12 00:00
Dawid Golunski

Strategic Overview

Status
Patched in 2.8.6
Affected Core
WordPress 2.8
Affected Version
<= 2.8.5
CVSS
8.8High
Weakness type
CWE-434 · Unrestricted Upload of File with Dangerous Type
CVE
CVE-2009-3890
View all WordPress 2.8 vulnerabilities

At a glance

CVE-2009-3890 is a high-severity Unrestricted Upload of File with Dangerous Type vulnerability in the WordPress 2.8 WordPress release line, affecting <= 2.8.5. 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 2.8.6; sites on affected versions should update now. Disclosed December 2009, reported by Dawid Golunski.

Vulnerability Overview

Unrestricted file upload vulnerability in the wp_check_filetype function in wp-includes/functions.php in WordPress before 2.8.6, when a certain configuration of the mod_mime module in the Apache HTTP Server is enabled, allows remote authenticated users to execute arbitrary code by posting an attachment with a multiple-extension filename, and then accessing this attachment via a direct request to a wp-content/uploads/ pathname, as demonstrated by a .php.jpg filename.

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 WordPress 2.8 <= 2.8.5 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 WordPress 2.8 the fix is 2.8.6: builds <= 2.8.5 are affected, anything from 2.8.6 onward is not.

Remediation

Update to version 2.8.6, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to WordPress 2.8: 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: updating to 2.8.6 is the step that ends it.

  • Firewall
  • Scanner
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2009-3890https://www.wordfence.com/threat-intel/vulnerabilities/id/f9ce0ae8-4729-4236-b4e8-e5726f4d3101https://nvd.nist.gov/vuln/detail/CVE-2009-3890

Related records

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