ICS Advisory (ICSA-20-016-01)

Schneider Electric Modicon Controllers (Update A)

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1. EXECUTIVE SUMMARY

  • CVSS v3 7.5
  • ATTENTION: Exploitable remotely/low skill level to exploit
  • Vendor: Schneider Electric
  • Equipment: Modicon M580, Modicon M340, Modicon Quantum, and Modicon Premium
  • Vulnerability: Improper Check for Unusual or Exceptional Conditions

2. UPDATE INFORMATION

This updated advisory is a follow-up to the original advisory titled ICSA-20-016-01 Schneider Electric Modicon Controllers that was published January 16, 2020, on the ICS webpage on us-cert.gov.

3. RISK EVALUATION

Successful exploitation of this vulnerability could result in a denial-of-service condition.

4. TECHNICAL DETAILS

4.1 AFFECTED PRODUCTS

The following versions of Modicon controllers, a PLC, are affected:
For CVE-2019-6857, the following Modicon controllers are affected:

  • Modicon M580, all versions prior to v2.80
  • Modicon M340, all versions prior to v3.01
  • Modicon Premium, all versions prior to v3.20
  • Modicon Quantum, all versions prior to v3.60

For CVE-2019-6856 and CVE-2018-7794, the following Modicon controllers are affected:

  • Modicon M580, all versions prior to v2.80
  • Modicon M340, all versions prior to v3.01
  • Modicon Premium, all versions prior to v3.20
  • Modicon Quantum, all versions prior to v3.52

4.2 VULNERABILITY OVERVIEW

4.2.1    IMPROPER CHECK FOR UNUSUAL OR EXCEPTIONAL CONDITIONS CWE-754

This vulnerability could cause a denial-of-service condition in the controller when reading specific memory blocks using Modbus TCP. 

CVE-2019-6857 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

4.2.2    IMPROPER CHECK FOR UNUSUAL OR EXCEPTIONAL CONDITIONS CWE-754

This vulnerability could cause a denial-of-service condition when writing specific physical memory blocks using Modbus TCP. 

CVE-2019-6856 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

4.2.3    IMPROPER CHECK FOR UNUSUAL OR EXCEPTIONAL CONDITIONS CWE-754

This vulnerability could cause a denial-of-service condition when reading data with invalid index using Modbus TCP. 

--------- Begin Update A Part 1 of 1 ---------

CVE-2018-7794 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

--------- End Update A Part 1 of 1 ---------

4.3 BACKGROUND

  • CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities, Critical Manufacturing, and Energy
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: France

4.4 RESEARCHER

Younes Dragoni of Nozomi Networks reported this vulnerability to CISA.

5. MITIGATIONS

Schneider Electric has developed the following mitigations:
Specific Modicon M580 firmware v3.10 is available at: 

Modicon M340 firmware v3.20 is available at:

Modicon Premium v3.20 firmware is available by contacting Schneider Electric customer support.
Modicon Quantum firmware v3.60 is available at:

Schneider Electric strongly recommends following industry cybersecurity best practices such as:

  • Locate control and safety system networks and remote devices behind firewalls, and isolate them from the business network.
  • Physical controls should be in place so that no unauthorized person would have access to the ICS and safety controllers, peripheral equipment, or the ICS and safety networks.
  • All controllers should reside in locked cabinets and never be left in the “Program” mode.
  • All programming software should be kept in locked cabinets and should never be connected to any network other than the network for which the devices are intended.
  • All methods of mobile data exchange with the isolated network, such as CDs, USB drives, etc., should be scanned before use in the terminals or any node connected to these networks.
  • Laptops that have connected to any other network besides the intended network should never be allowed to connect to the safety or control networks without proper sanitation.
  • Minimize network exposure for all control system devices and/or systems, and ensure that they are not accessible from the Internet.
  • 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.

For more information on this vulnerability and the associated upgrade, please see Schneider Electric’s SEVD-2019-344-01

For more details and assistance on how to protect during installation, please contact a Schneider Electric representative and/or Schneider Electric Industrial Cybersecurity Services. These organizations are aware of this situation and can support you through the process.

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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