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1. EXECUTIVE SUMMARY

CVSS v3 6.5
ATTENTION: Exploitable remotely/low attack complexity
Vendor: Mitsubishi Electric
Equipment: CC-Link IE TSN Industrial Managed Switch
Vulnerabilities: Observable Timing Discrepancy, Double Free

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could result in disclosure of information stored in the product by sending specially crafted packets or could cause a denial-of service (DoS) condition by getting a legitimate user to import a specially crafted certificate

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Mitsubishi Electric products are affected:

CC-Link IE TSN Industrial Managed Switch, model NZ2MHG-TSNT8F2 NZ2MHG-TSNT4: All versions

3.2 Vulnerability Overview

3.2.1 OBSERVABLE TIMING DISCREPANCY CWE-208

An attacker could decrypt ciphertext and disclose sensitive information by sending specially crafted packets and performing a Bleichenbacher style attack.

CVE-2022-4304 has been assigned to this vulnerability. A CVSS v3 base score of 5.9 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N).

3.2.2 DOUBLE FREE CWE-415

An attacker could cause a denial-of-service (DoS) condition on the product by leading a legitimate user to import a malicious certificate.

CVE-2022-4450 has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:R/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

Mitsubishi Electric reported this these vulnerabilities to CISA.

4. MITIGATIONS

Mitsubishi Electric recommends that customers take the following mitigations to minimize the risk of exploitation of these vulnerabilities:

When internet access is required, use a virtual private network (VPN) or other means to prevent unauthorized access.
Use the products within a LAN and block access from untrusted networks and hosts.
Restrict physical access to your computer and network equipment on the same network.
After you log into NZ2MHG-TSNT8F2 or NZ2MHG-TSNT4 with the web interface, change user name and password from default setting at [Account Management] displayed on the function menu. Also, set the proper access permissions for the users.

For specific update instructions and additional details see Mitsubishi Electric advisory 2023-011.

CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities, such as:

Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
Locate control system networks and remote devices behind firewalls and isolating them from business networks.

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 cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing suspected malicious activity should follow established internal procedures and report 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 attachments in unsolicited 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 exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.

5. UPDATE HISTORY

October 5, 2023: Initial Publication