Security Brief: Rockwell Automation CVE-2021-22681
March 18, 2021

Security Brief: Rockwell Automation CVE-2021-22681

There is a recent vulnerability released in Rockwell Automation software where the authentication mechanism for communication to PLC’s has been compromised.

Rockwell controllers use a security key to validate that PLC’s are connecting with Rockwell Automation software. There is a vulnerability in RSLogix (v16-20) / Studio 5000 (v21+) where this key has been compromised, allowing any third-party tool to alter the controller’s configuration. A CVSS v3 base score of 10.0 has been calculated (maximum). This is a very severe vulnerability if exploited could impact production wherever vulnerable PLCs are used.

The following PLC’s are affected:

  • CompactLogix 1768
  • CompactLogix 1769
  • CompactLogix 5370
  • CompactLogix 5380
  • CompactLogix 5480
  • ControlLogix 5550
  • ControlLogix 5560
  • ControlLogix 5570
  • ControlLogix 5580
  • DriveLogix 5560
  • DriveLogix 5730
  • DriveLogix 1794-L34
  • Compact GuardLogix 5370
  • Compact GuardLogix 5380
  • GuardLogix 5570
  • GuardLogix 5580
  • SoftLogix 5800

Proper network segmentation and security controls should be implemented to reduce the exposure to these devices.

Cybertrol recommends the following should be considered as part of a defense in depth strategy.

  • Limit access to PLC’s from dedicated and monitored programming servers.
  • Limit access to programming servers with multi-factor authentication through a DMZ architecture.
  • Ensure equipment has vulnerabilities patched to reduce the chance of running code exploiting this vulnerability. (Especially firewalls and servers, and DMZ infrastructure.)
  • Implement a DMZ architecture without direct access to production equipment from above the DMZ.
  • Ensure production systems are not accessible from the internet.
  • Locate production networks behind a firewall to limit access from the DMZ and business networks.
  • Utilize secure methods of remote access when required.
  • Ensure methods of remote access is up to date to minimize any potential vulnerabilities.
  • Put controller’s mode switch into ‘Run’ – only place in ‘Rem’ for the time it takes to implement changes. Immediately switch back to ‘Run’ after any changes.
  • Implement CIP security with the front ethernet ports on controllers, or with a 1756-EN4TR.
  • Monitor the controller change log for any unexpected modifications or activity.
  • Utilize change detection in Logix Designer.
  • Use AssetCentre to detect changes where available.
  • Monitor PLC traffic to identify any unexpected devices communicating with the controller.

For additional information, you can review the Cybersecurity and Infrastructure Security Agency page on this vulnerability.  You can also download a sharable PDF of this notice here.

If you would like to speak to one of our cybersecurity experts, contact us and one of our Industrial IT team members will evaluate your production network and provide recommendations to achieve a secure and maintainable network infrastructure.