Multiple Vulnerabilities in Drupal Could Allow for Remote Code Execution

ITS Advisory Number: 
2017-061
Date(s) Issued: 
Thursday, June 22, 2017
Subject: 
Multiple Vulnerabilities in Drupal Could Allow for Remote Code Execution
Overview: 

Multiple vulnerabilities have been discovered in Drupal core module, the most severe of which could allow for remote code execution. Drupal is an open source content management system (CMS) written in PHP. Successful exploitation of the most severe of these vulnerabilities could allow for remote code execution. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.

Systems Affected: 
  • Drupal Core versions prior to 8.3.4 and 7.56

RISK
GOVERNMENT
Large and medium government entities: 
High
Small government entities: 
Medium
BUSINESS
Large and medium business entities: 
High
Small business entities: 
Medium
Home Users: 
Low
Description: 

Multiple vulnerabilities have been discovered in Drupal core modules, the most severe of which could result in remote code execution. Details of the vulnerabilities are as follows:

  • A remote code execution vulnerability exists because PECL YAML parser does not handle PHP objects safely during certain operations within Drupal core. (CVE-2017- 6920)

  • An access vulnerability exists because the file REST resource does not properly validate some fields when manipulating files. (CVE-2017- 6921)

  • An access vulnerability exists because files uploaded by anonymous users into a private file system can be accessed by other anonymous users. (CVE-2017- 6922)

Successful exploitation of the most severe of these vulnerabilities could allow for remote code execution. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.

Actions: 
  • After appropriate testing, immediately apply the updates provided by Drupal to the vulnerable systems.

  • Ensure no unauthorized systems changes have occurred before applying patches.

  • Run all software as a non-privileged user to diminish effects of a successful attack.

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