Schneider Electric Modicon M221 Programmable Logic Controller

1. EXECUTIVE SUMMARY

• CVSS v3 7.1
• ATTENTION: Exploitable from an adjacent network
• Vendor: Schneider Electric
• Equipment: Modicon M221 Programmable Logic Controller
• Vulnerabilities: Inadequate Encryption Strength, Small Space of Random Values, Missing Encryption of Sensitive Data, Exposure of Sensitive Information, Use of a One-Way Hash with a Predictable Salt

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to take control over the PLC and gain unauthorized access, which could result in exposure of sensitive information.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

Schneider Electric reports these vulnerabilities affect the following Modicon products:

• Modicon M221: All versions

3.2 VULNERABILITY OVERVIEW

3.2.1    INADEQUATE ENCRYPTION STRENGTH CWE-326

An inadequate encryption strength vulnerability exists that could allow the attacker to break the encryption key when the attacker has captured the traffic between EcoStruxure Machine - Basic software and Modicon M221 controller.

CVE-2020-7565 has been assigned to this vulnerability. A CVSS v3 base score of 7.1 has been calculated; the CVSS vector string is (AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H).

3.2.2    SMALL SPACE OF RANDOM VALUES CWE-334

A small space of random values vulnerability exists that could allow the attacker to break the encryption keys when the attacker has captured the traffic between EcoStruxure Machine - Basic software and Modicon M221 controller.

CVE-2020-7566 has been assigned to this vulnerability. A CVSS v3 base score of 7.1 has been calculated; the CVSS vector string is (AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H).

3.2.3    MISSING ENCRYPTION OF SENSITIVE DATA CWE-311

A missing encryption of sensitive data vulnerability exists that could allow the attacker to find the password hash when the attacker has captured the traffic between EcoStruxure Machine - Basic software and Modicon M221 controller and has broken the encryption keys.

CVE-2020-7567 has been assigned to this vulnerability. A CVSS v3 base score of 7.1 has been calculated; the CVSS vector string is (AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H).

3.2.4    EXPOSURE OF SENSITIVE INFORMATION CWE-200

An exposure of sensitive information to an unauthorized actor vulnerability exists that could allow non-sensitive information disclosure when the attacker has captured the traffic between EcoStruxure Machine - Basic software and Modicon M221 controller.

CVE-2020-7568 has been assigned to this vulnerability. A CVSS v3 base score of 3.1 has been calculated; the CVSS vector string is (AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N).

3.2.5    USE OF A ONE-WAY HASH WITH A PREDICTABLE SALT CWE-760

A use of a one-way hash with a predictable salt vulnerability exists that could allow the attacker to pre-compute the hash value using a dictionary attack, effectively disabling the protection that an unpredictable salt would provide.

CVE-2020-28214 has been assigned to this vulnerability. A CVSS v3 base score of 3.3 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities, Energy, Food and Agriculture, Government Facilities, Transportation Systems, Water and Wastewater Systems
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: France

3.4 RESEARCHER

Yehuda Anikster and Rei Henigman of Claroty, and Seok Min Lim and Bryon Kaan of Trustwave reported these vulnerabilities to Schneider Electric.

4. MITIGATIONS

Schneider Electric recommends users to apply the following mitigations to help reduce the risk of exploit:

• Set up network segmentation and implement a firewall to block all unauthorized access to Port 502/TCP.
• Within the Modicon M221 application, the user must:
  • Disable all unused protocols, especially programming protocol, as described in section “Configuring Ethernet Network” of EcoStruxure Machine Expert - Basic online help for the M221 PLC. This action will prevent unintended remote programming access.
  • Set a password to protect the project.
  • Set a password for read access on the controller.
  • Set a different password for write access on the controller.

Schneider Electric strongly recommends following industry cybersecurity best practices:

• Locate control and safety system networks and remote devices behind firewalls and isolate them from the business network.
• Install physical controls so no unauthorized personnel can access industrial control and safety systems, components, peripheral equipment, and networks.
• Place all controllers in locked cabinets and never leave them in the “Program” mode.
• Never connect programming software to any network other than the network for which the devices were intended.
• Scan all methods of mobile data exchange with the isolated network (e.g., CDs, USB drives, etc.) before use in the terminals or any node connected to these networks.
• Never allow mobile devices that have connected to any other network, besides the intended network, to connect to the safety or control networks without proper sanitation.
• Minimize network exposure for all control system devices and 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). Recognize that VPNs may have vulnerabilities and should be updated to the most current version available. Also, understand that VPNs are only as secure as the connected devices.

For more information refer to the Schneider Electric Recommended Cybersecurity Best Practices document.

Refer to Schneider Electric’s security bulletin SEVD-2020-315-05 for specific mitigation details.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. 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: 

• Do not click web links or open unsolicited attachments in email messages. 
• Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams. 
• Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks.

No known public exploits specifically target these vulnerabilities. High skill level is needed to exploit.

• Schneider Electric