ICS Advisory (ICSA-21-257-23)

Siemens SIMATIC and TIM

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  • CVSS v3 5.3
  • ATTENTION: Exploitable remotely/low attack complexity
  • Vendor: Siemens
  • Equipment: SIMATIC, TIM
  • Vulnerability: Incorrect Authorization


Successful exploitation of this vulnerability allows an unauthenticated attacker to read PLC variables from affected devices without proper authentication under certain circumstances.



The following Siemens products are affected:    

  • SIMATIC Drive Controller family: All versions prior to v2.9.2
  • SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants): All versions prior to v21.9
  • SIMATIC S7 PLCSIM Advanced: All versions higher than v2 and prior to v4
  • SIMATIC S7-1200 CPU family (incl. SIPLUS variants): Version 4.4
  • SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants): All versions higher than v2.5 and prior to v2.9.2
  • SIMATIC S7-1500 Software Controller: All versions higher than v2.5
  • TIM 1531 IRC (incl. SIPLUS NET variants): Version 2.1



The affected products are vulnerable to an incorrect authorization check, allowing an attacker to extract information about access protected PLC program variables when simultaneously reading multiple attributes.

CVE-2020-28397 has been assigned to this vulnerability. A CVSS v3.1 base score of 5.3 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N).




Siemens reported this vulnerability to CISA.


Siemens recommends users update to the latest software version:

  • SIMATIC Drive Controller family: Update to v2.9.2 or later
  • SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants): Update to v21.9 or later
  • SIMATIC S7 PLCSIM Advanced: Update to v4 or later
  • SIMATIC S7-1200 CPU family (incl. SIPLUS variants): Update to v4.4.1 or later
  • SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants): Update to v2.9.2 or later
  • •    SIMATIC S7-1500 Software Controller: Update to v21.9 or later version 
  • TIM 1531 IRC (incl. SIPLUS NET variants): Update to v2.2 or later

Siemens has not identified any additional specific mitigations or workarounds for this vulnerability. Please follow the general security recommendations below.

As a general security measure, Siemens strongly recommends users protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends users configure the environment according to Siemens operational guidelines for industrial security and follow the recommendations in the product manual.

Additional information on industrial security by Siemens can be found at: https://www.siemens.com/industrialsecurity

For more information about this issue, please see Siemens Security Advisory SSA-865327

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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