ShortPixel Image Optimizer <= 5.4.1 - Authenticated(Editor+) PHP Object Injection

2023-09-14 00:00
Anonymous

Strategic Overview

Status
Patched in 5.4.2
Affected Plugin
ShortPixel Image Optimizer – Optimize Images, Convert WebP & AVIF
Affected Version
< 5.4.2
CVSS
6.6Medium
Weakness type
CWE-502 · Deserialization of Untrusted Data
CVE
CVE pending
View all ShortPixel Image Optimizer – Optimize Images, Convert WebP & AVIF vulnerabilities

At a glance

This record tracks a medium-severity Deserialization of Untrusted Data vulnerability in the ShortPixel Image Optimizer WordPress plugin, affecting versions < 5.4.2. It carries a CVSS score of 6.6 (reachable over the network; high confidentiality, integrity, availability impact). Exploitation requires an authenticated account at Editor level or above. The issue is fixed in version 5.4.2; sites on affected versions should update now. Disclosed September 2023.

Vulnerability Overview

The ShortPixel Image Optimizer plugin for WordPress is vulnerable to PHP Object Injection in versions up to, and including, 5.4.1 via deserialization of untrusted input in post content. This allows authenticated attackers with editor capabilities or above to inject a PHP Object. No POP chain is present in the vulnerable plugin. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-502: Deserialization of Untrusted Data

Reaching this weakness in ShortPixel Image Optimizer < 5.4.2 takes an account at Editor level or above. Deserialization of untrusted data means the application reconstructs objects from input a caller controls, letting the attacker choose which classes get instantiated and what their properties hold.

A workable chain turns deserialization into file writes, deletions or code execution, depending on what the loaded classes do in their magic methods. For ShortPixel Image Optimizer the fix is 5.4.2: builds < 5.4.2 are affected, anything from 5.4.2 onward is not.

Remediation

Update to version 5.4.2, or a newer patched version

How does WordSec protect against this?

An attacker needs Editor access first, so the firewall sees the attempt as traffic from a logged-in account: 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: ShortPixel Image Optimizer 5.4.2 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/9f23bf62-6008-4a9c-a7ae-a2e513699684

Related records

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