ICS Advisory (ICSA-20-014-03)

Siemens SCALANCE X Switches

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1. EXECUTIVE SUMMARY

  • CVSS v3 8.8
  • ATTENTION: Exploitable remotely/low skill level to exploit
  • Vendor: Siemens
  • Equipment: SCALANCE X Switches
  • Vulnerability: Missing Authentication for Critical Function

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an unauthenticated attacker to violate access-control rules.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of SCALANCE X Switches, used to connect industrial components, are affected:

  • All versions of the SCALANCE X-200RNA switch family
  • All versions prior to Version 4.1.3 of the SCALANCE X-300 switch family (including SIPLUS NET variants)
  • All versions prior to Versions 4.1.3 of the SCALANCE X-408

3.2 VULNERABILITY OVERVIEW

3.2.1    MISSING AUTHENTICATION FOR CRITICAL FUNCTION CWE-306

This vulnerability could be exploited by an attacker with network access to the affected systems. An attacker could obtain sensitive information or change the device configuration.

CVE-2019-13933 has been assigned to this vulnerability. A CVSS v3 base score of 8.8 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L).

3.3 BACKGROUND

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

3.4 RESEARCHER

Maxim Rupp reported this vulnerability to Siemens.

4. MITIGATIONS

Siemens recommends the following workarounds and mitigations affected users can apply to reduce risk:

For the SCALANCE X-200RNA switch family Siemens recommends:

  • Configure ACLs to only allow Web-based management from trusted IP addresses.
  • Disable web-based management (WBM) and use SSH to configure the device.

For the SCALANCE X-300 switch family (including SIPLUS NET variants), Siemens recommends that users upgrade to Version 4.1.3

For the SCALANCE X-408, Siemens recommends that users upgrade to Version 4.1.3

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 manuals.

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

For more information see the Siemens security advisory.

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.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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