A Vulnerability in vBulletin Could Allow for Remote Code Execution

ITS Advisory Number: 
2019-102
Date(s) Issued: 
Friday, September 27, 2019
Subject: 
A Vulnerability in vBulletin Could Allow for Remote Code Execution
Overview: 

A vulnerability has been discovered in vBulletin which could allow for remote code execution when a malicious POST request is sent to the vulnerable application. vBulletin is a software package written in PHP used to create forums. Successful exploitation of this vulnerability could enable the attacker to perform system command execution in the context of the web server hosting the application. Depending on the privileges associated with the vBulletin service, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

Systems Affected: 
  • vBulletin versions 5.0.0 to 5.5.4
RISK
GOVERNMENT
Large and medium government entities: 
Medium
Small government entities: 
Medium
BUSINESS
Large and medium business entities: 
Medium
Small business entities: 
Medium
Home Users: 
Low
Description: 

A vulnerability has been discovered in vBulletin which can allow for remote code execution when a malicious POST request is sent to the vulnerable application. This vulnerability exists due to improper input validation within the widgetConfig[code] parameter when a POST request is sent to the index page of the vBulletin with the routestring, "ajax/render/widget_php". An attacker can load an arbitrary widget and run code provided within the widgetConfig[code] parameter. Depending on the privileges associated with the vBulletin service, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

Actions: 
  • After appropriate testing, immediately apply patches or appropriate mitigations provided by vBulletin to vulnerable systems.

  • Run all software as a non-privileged user (one without administrative rights) to diminish the effects of a successful attack.

  • Remind all users not to visit untrusted websites or follow links provided by unknown or untrusted sources.

  • Apply the Principle of Least Privilege to all systems and services.