ICS Advisory (ICSA-21-131-15)

Siemens SIMATIC S7-1500

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1. EXECUTIVE SUMMARY

  • CVSS v3 7.8
  • ATTENTION: Low attack complexity
  • Vendor: Siemens
  • Equipment: SIMATIC S7-1500 CPU 1518F-4
  • Vulnerabilities: Improper Initialization, Improper Restriction of Operations within the Bounds of a Memory Buffer

2. RISK EVALUATION

Successful exploitation of these Intel product vulnerabilities could allow unauthorized privilege escalation.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of SIMATIC S7-1500 CPU 1518-4, are affected by vulnerabilities in Intel products:

  • SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (MLFB: 6ES7518-4AX00-1AC0, 6AG1518-4AX00-4AC0, incl. SIPLUS variant): All versions
  • SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (MLFB: 6ES7518-4FX00-1AC0): All versions

3.2 VULNERABILITY OVERVIEW

3.2.1    IMPROPER INITIALIZATION CWE-665

Improper initialization in subsystem for Intel(R) CSME may allow a privileged user to enable escalation of privilege via local access.

CVE-2020-8744 has been assigned to this vulnerability. A CVSS v3 base score of 7.8 has been assigned; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

3.2.2    IMPROPER RESTRICTION OF OPERATIONS WITHIN THE BOUNDS CWE-119

Improper buffer restrictions in BIOS firmware for some Intel(R) Processors may allow a privileged user to enable escalation of privilege via local access.

CVE-2020-0591 has been assigned to this vulnerability. A CVSS v3 base score of 6.7 has been assigned; the CVSS vector string is (AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H).

3.3 BACKGROUND

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

3.4 RESEARCHER

Siemens reported these vulnerabilities to CISA.

4. MITIGATIONS

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

  • As a prerequisite for an attack, an attacker must be able to run untrusted code on affected systems. Siemens recommends limiting the possibilities to run untrusted code if possible.
  • Applying a Defense-in-Depth concept can help to reduce the probability that untrusted code is run on the system. Siemens recommends applying the Defense-in-Depth concept.

For additional information, please refer to Siemens Security Advisory SSA-501073 

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 these vulnerabilities. These vulnerabilities are not exploitable remotely.


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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