1. EXECUTIVE SUMMARY
- CVSS v3 7.5
- ATTENTION: Exploitable remotely/low attack complexity
- Vendor: JTEKT Corporation
- Equipment: TOYOPUC products
- Vulnerability: Improper Resource Shutdown or Release
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an unauthorized user to stop Ethernet communications between devices from being established.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of these TOYOPUC product series are affected:
- TOYOPUC-PC10 Series:
- PC10G-CPU TCC-6353: All versions
- PC10GE TCC-6464: All versions
- PC10P TCC-6372: All versions
- PC10P-DP TCC-6726: All versions
- PC10P-DP-IO TCC-6752: All versions
- PC10B-P TCC-6373: All versions
- PC10B TCC-1021: All versions
- PC10B-E/C TCU-6521: All versions
- PC10E TCC-4737: All versions
TOYOPUC-Plus Series:
- Plus CPU TCC-6740: All versions
- Plus EX TCU-6741: All versions
- Plus EX2 TCU-6858: All versions
- Plus EFR TCU-6743: All versions
- Plus EFR2 TCU-6859: All versions
- Plus 2P-EFR TCU-6929: All versions
- Plus BUS-EX TCU-6900: All versions
TOYOPUC-PC3J/PC2J Series:
- FL/ET-T-V2H THU-6289: All versions
- 2PORT-EFR THU-6404: All versions
3.2 VULNERABILITY OVERVIEW
3.2.1 IMPROPER RESOURCE SHUTDOWN OR RELEASE CWE-404
If Ethernet communication of the affected product is left in an open state by an attacker, Ethernet communications cannot be established with other devices, depending on the settings of the link parameters.
CVE-2021-27458 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
3.3 BACKGROUND
- CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
- COUNTRIES/AREAS DEPLOYED: Worldwide
- COMPANY HEADQUARTERS LOCATION: Japan
3.4 RESEARCHER
Younes Dragoni from Nozomi Networks reported this vulnerability to CISA.
4. MITIGATIONS
JTEKT Corporation recommends users to use the following workaround:
- Access the link parameter screen of either “Ethernet” or “Ethernet (32Port).”
- Access the Timer setting by clicking on the “Timers” button.
- Set “Non-Reception timer” to “Enable” in the “Timers” section.
- After setting the link parameter, connect a computer and a PLC with a USB cable and write the link parameter.
- After the writing is completed, perform a reset/start or power-on again.
- After reset/start or power-on, the parameter changes take effect.
- When “Non-Reception timer” is set to “Enabled,” the connection that was not closed correctly can be reset after the set time has elapsed and a connection can communicate with a device that should be connected.
Requests for additional information can be sent to JTEKT Corporation at JJP_PSIRT@jtekt.co.jp
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.
No known public exploits specifically target this vulnerability.
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