ICS Advisory (ICSA-21-238-01)

Johnson Controls Controlled Electronic Management Systems CEM Systems AC2000

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  • CVSS v3 8.2
  • ATTENTION: Exploitable remotely/low attack complexity
  • Vendor: Controlled Electronic Management Systems Ltd., a subsidiary of Johnson Controls Inc
  • Equipment: CEM Systems AC2000
  • Vulnerability: Improper Authorization


Under specific conditions, successful exploitation of this vulnerability could allow a remote attacker access to the system without adequate authorization.



Johnson Controls reports this vulnerability affects the following versions of CEM Systems AC2000:

  • Versions 10.1 through 10.5

This vulnerability applies only to users who have implemented Single Sign On (SSO) and have installed the AC2000 Application Programming Interface (API).



Under certain conditions, the application does not perform an adequate authorization check for functionality that requires a provable user identity.

CVE-2021-27663 has been assigned to this vulnerability. A CVSS v3 base score of 8.2 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N).


  • CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities, Critical Manufacturing


Johnson Controls, Inc., reported this vulnerability to CISA.


Johnson Controls recommends steps to minimize risks to applying a patch to all affected versions and implementations. The fix will also be included in Version 10.5 Server Feature Pack 2, Version 10.6, and all future releases.

To access the patch, affected users should contact a CEM support team.

For more detailed mitigation instructions, please see Johnson Controls Product Security Advisory JCI-PSA-2021-15 v1

Aligning with CISA recommendations, Johnson Controls recommends taking steps to minimize risks to all building automation systems.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:

  • Minimize network exposure for all control system devices and/or systems, and ensure that they are not accessible from the Internet.
  • Locate control system networks and remote devices behind firewalls, and isolate them from the business network.
  • When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing that VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize that VPN is only as secure as the connected devices.

CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

CISA also provides a section for control systems security recommended practices on the ICS webpage on us-cert.cisa.gov. Several recommended practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage on us-cert.cisa.gov in the Technical Information Paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to CISA for tracking and correlation against other incidents.

No known public exploits specifically target this vulnerability.

Contact Information

For any questions related to this report, please contact the CISA at:

Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  https://us-cert.cisa.gov/ics 
or incident reporting:  https://us-cert.cisa.gov/report

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