Hitachi Energy RTU500 series BCI

1. EXECUTIVE SUMMARY

• CVSS v3 7.5
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Hitachi Energy
• Equipment: RTU500 series Bidirectional Communication Interface (BCI)
• Vulnerability: Improper Input Validation

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow a remote attacker to reboot the device.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following firmware versions of RTU500 series, a remote terminal unit, are affected:

• RTU500 series CMU Firmware Version 12.0: All versions
• RTU500 series CMU Firmware Version 12.2: All versions
• RTU500 series CMU Firmware Version 12.4: All versions

3.2 VULNERABILITY OVERVIEW

3.2.1    IMPROPER INPUT VALIDATION CWE-20

An issue exists in the BCI IEC 60870-5-104 function included in the affected products. If BCI IEC 60870-5-104 is enabled and configured, an attacker could exploit the vulnerability by sending a specially crafted message to the affected product, causing it to reboot. This vulnerability is caused by the validation error in the APDU parser of the BCI IEC 60870-5-104 function.

CVE-2021-35533 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: Energy
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Switzerland

3.4 RESEARCHER

Hitachi Energy reported this vulnerability to CISA.

4. MITIGATIONS

Hitachi Energy recommends the following:

• Disable BCI IEC 60870-5-104 function by configuration if it is not used. Note: By default, the BCI IEC 60870-5-104 is disabled.
• Update to RTU500 series CMU Firmware Version 12.6.5.0 or later (e.g., RTU500 CMU Firmware Version 12.7.* or CMU Firmware Version 13.2.* or later).

Please see Hitachi Energy advisory 8DBD000063 for additional mitigation and update information.

Hitachi Energy recommends the following security practices and firewall configurations to help protect process control networks from attacks that originate from outside the network:

• Physically protect process control systems from direct access by unauthorized personnel.
• Do not directly connect to the Internet.
• Separated from other networks by means of a firewall system with a minimal number of ports exposed.
• Process control systems should not be used for Internet surfing, instant messaging, or receiving e-mails.
• Portable computers and removable storage media should be carefully scanned for viruses before they are connected to a control system.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.

• Hitachi Energy