ICS Advisory (ICSA-20-224-04)

Siemens SCALANCE, RUGGEDCOM

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1. EXECUTIVE SUMMARY

  • CVSS v3 9.8
  • ATTENTION: Exploitable remotely/low skill level to exploit
  • Vendor: Siemens
  • Equipment: SCALANCE, RUGGEDCOM
  • Vulnerability: Classic Buffer Overflow

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an attacker to gain unauthenticated access to a device and cause a buffer overflow to execute custom code.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following Siemens products are affected:

  • RUGGEDCOM RM1224: All versions prior to 6.3
  • SCALANCE M-800 / S615: All versions prior to 6.3

3.2 VULNERABILITY OVERVIEW

3.2.1    BUFFER COPY WITHOUT CHECKING SIZE OF INPUT (‘CLASSIC BUFFER OVERFLOW’) CWE-120

The version of pppd shipped with this product has a vulnerability that may allow an unauthenticated remote attacker to cause a stack buffer overflow, which may allow arbitrary code execution on the target system.

CVE-2020-8597 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: Chemical, Energy, Food and Agriculture, Water and Wastewater Systems
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Siemens reported this vulnerability to CISA.

4. MITIGATIONS

Siemens recommends applying the following updates:

  • RUGGEDCOM RM1224: Update to v6.3
  • SCALANCE M-800: Update to v6.3

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

  • Only use the PPP functionality of the affected devices in trusted environments. This functionality is not enabled by default but typically used in internet dial-in or point-to-point connection scenarios. At this point the vulnerability could be exploited by a malicious peer.

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-809841

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.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.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://www.us-cert.gov/ics 
or incident reporting:  https://www.us-cert.gov/report

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