NextGen Gallery <= 3.1.5 - PHP Object Injection

2019-02-04 00:00
Slavco Mihajloski

Strategic Overview

Status
Patched in 3.1.6
Affected Plugin
Photo Gallery, Sliders, Proofing and Themes – NextGEN Gallery
Affected Version
<= 3.1.5
CVSS
8.8High
Weakness type
CWE-502 · Deserialization of Untrusted Data
CVE
CVE pending
View all Photo Gallery, Sliders, Proofing and Themes – NextGEN Gallery vulnerabilities

At a glance

This record tracks a high-severity Deserialization of Untrusted Data vulnerability in the Photo Gallery, Sliders, Proofing and Themes WordPress plugin, affecting versions <= 3.1.5. 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 3.1.6; sites on affected versions should update now. Disclosed February 2019, reported by Slavco Mihajloski.

Vulnerability Overview

The NextGen Gallery plugin for WordPress is vulnerable to PHP Object Injection in versions up to, and including, 3.1.5. This is due to the plugin unserializing serialized data obtained via user supplied input from the `sortorder` parameter. This makes it possible for authenticated attackers to call arbitrary PHP Objects and achieve remote code execution when the right gadgets are available.

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-502: Deserialization of Untrusted Data

Reaching this weakness in Photo Gallery, Sliders, Proofing and Themes <= 3.1.5 takes a caller who can reach the endpoint. 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 Photo Gallery, Sliders, Proofing and Themes the fix is 3.1.6: builds <= 3.1.5 are affected, anything from 3.1.6 onward is not.

Remediation

Update to version 3.1.6, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Photo Gallery, Sliders, Proofing and Themes: 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: Photo Gallery, Sliders, Proofing and Themes 3.1.6 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/a67eb1fc-4762-4bdc-b0a0-c043c36659d0

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