ICS Advisory (ICSA-21-222-06)

Siemens Energy AGT and SGT Solutions

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1. EXECUTIVE SUMMARY

  • CVSS v3 9.8
  • ATTENTION: Exploitable remotely/low attack complexity
  • Vendor: Siemens
  • Equipment: SGT
  • Vulnerability: Out-of-bounds Write

2. RISK EVALUATION

Successful exploitation of this vulnerability could lead to remote code execution.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following Siemens products are affected:

  • SGT-100: All versions
  • SGT-200: All versions
  • SGT-300: All versions
  • SGT-400: All versions
  • SGT-A20: All versions
  • SGT-A35: All versions
  • SGT-A64: All versions

3.2 VULNERABILITY OVERVIEW

3.2.1    OUT-OF-BOUNDS WRITE CWE-787

A DNS client stack-based buffer overflow in ipdnsc_decode_name() affects Wind River VxWorks v6.5 through v7

CVE-2016-20009 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

3.3 BACKGROUND

  • CRITICAL INFRASTRUCTURE SECTORS: Multiple Sectors
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Siemens reported to CISA that these products are affected by this vulnerability when using some third-party components.

4. MITIGATIONS

Updates are for affected Rockwell Automation / Allen Bradley components in use within Siemens products. Please see Rockwell Security Advisory PN1564 (login required) for affected parts and software/firmware updates. Some updates may not be compatible with other components in the system. Contact Siemens Energy for further support.

Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:

  • While firmware updates are suggested as solutions, the updates may not be compatible with the software or other components in the system. Please contact a Siemens Energy representative for an assessment.
  • For more details on how to mitigate this vulnerability, see Rockwell Security Advisory PN1564 (login required).

As a general security measure, Siemens strongly recommends protecting network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends configuring the environment according to the Siemens operational guidelines for industrial security and following the recommendations in the product manuals.

For additional information, please refer to Siemens Security Advisory SSA-553445

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 VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as its 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.

CISA also recommends users take the following measures to protect themselves from social engineering attacks:

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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