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Multiple Vulnerabilities in Drupal Could Allow for Remote Code Execution

MS-ISAC ADVISORY NUMBER:

2018-117

DATE(S) ISSUED:

10/18/2018

OVERVIEW:

Multiple vulnerabilities has been discovered in the 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.

THREAT INTELLIGENCE:

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

SYSTEMS AFFECTED:

  • Drupal Core versions prior to 7.60, 8.6.2, and 8.5.8

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:

Multiple vulnerabilities have been discovered in Drupal core module, the most severe of which could allow for remote code execution. The remote code execution vulnerability exists within the default Drupal mail system because of improper sanitization for shell arguments, which could result in a website being completely compromised. Details of the vulnerabilities are as follows:

  • In some conditions, content moderation fails to check a users access to use certain transitions, leading to an access bypass.
  • External URL injection through URL aliases could allow for open redirect.
  • Anonymous Open Redirect if a user clicks on a specially crafted URL using the destination query string.
  • Injection in DefaultMailSystem::mail() due to variables not being sanitized for shell arguments could allow for Remote Code Execution.
  • The Contextual Links module did not sufficiently validate requested contextual links. When exploited this vulnerability could allow for Remote Code Execution.

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.

RECOMENDATIONS:

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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