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A Vulnerability in Drupal Could Allow for Remote Code Execution

MS-ISAC ADVISORY NUMBER:

2019-024

DATE(S) ISSUED:

02/22/2019

OVERVIEW:

A vulnerability has been discovered in the Drupal core module, which could allow for remote code execution. Drupal is an open source content management system (CMS) written in PHP. Successful exploitation of this vulnerability 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.

THREAT INTELLIGENCE:

There are currently no reports of this vulnerability being exploited in the wild.

**February 26 – UPDATED THREAT INTELLIGENCE:
Drupal has announced that there are known exploits for this vulnerability.

SYSTEMS AFFECTED:

  • Drupal Core versions prior to 8.6.10 and 8.5.11

RISK:

Government:
  • Large and medium government entities: HIGH
  • Small government entities: HIGH
Businesses:
  • Large and medium business entities: HIGH
  • Small business entities: HIGH
Home Users:
LOW

TECHNICAL SUMMARY:

A vulnerability has been discovered in the Drupal core module, which could allow for remote code execution. The remote code execution vulnerability exists due to a lack of proper data sanitization in some fields, which could result in a website being completely compromised. Detail of the vulnerability is included below:

  • Some field types do not properly sanitize data from non-form sources. This can lead to arbitrary PHP code execution in some cases. (CVE-2019-6340)

According to Drupal the following can be done to immediately mitigate the vulnerability:

Disable all web services modules, or configure your web server(s) to not allow PUT/PATCH/POST requests to web services resources. Note that web services resources may be available on multiple paths depending on the configuration of your server(s). For Drupal 7, resources are for example typically available via paths (clean URLs) and via arguments to the "q" query argument. For Drupal 8, paths may still function when prefixed with index.php/.

Successful exploitation of this vulnerability 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.

February 26 – UPDATED TECHNICAL SUMMARY:
Any enabled REST resource end-point, even if it only accepts GET requests is vulnerable. To immediately mitigate the vulnerability, you can disable all web services modules, or configure your web server(s) to not allow GET/PUT/PATCH/POST requests to web services resources.

RECOMMENDATIONS:

We recommend the following actions be taken:

  • Apply appropriate patches provided by Drupal to vulnerable systems immediately after appropriate testing.
  • Ensure no unauthorized system 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.
  • Drupal version 8.4.x and earlier sites should be migrated to supported Drupal versions as soon as possible after patches are applied.

REFERENCES:

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