Westermo L210-F2G

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1. EXECUTIVE SUMMARY

• CVSS v4 8.7
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Westermo
• Equipment: L210-F2G Lynx
• Vulnerabilities: Cleartext Transmission of Sensitive Information, Improper Control of Interaction Frequency

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could crash the device being accessed or may allow remote code execution.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Westermo L210-F2G industrial ethernet switches are affected:

• L210-F2G Lynx: version 4.21.0

3.2 Vulnerability Overview

3.2.1 Cleartext Transmission of Sensitive Information CWE-319

Plain text credentials and session ID can be captured with a network sniffer.

CVE-2024-37183 has been assigned to this vulnerability. A CVSS v3.1 base score of 5.7 has been calculated; the CVSS vector string is (AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N).

A CVSS v4 score has also been calculated for CVE-2024-37183. A base score of 6.9 has been calculated; the CVSS vector string is (CVSS4.0/AV:A/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N).

3.2.2 Improper Control of Interaction Frequency CWE-799

An attacker may be able to cause a denial-of-service condition by sending many packets repeatedly.

CVE-2024-35246 has been assigned to this vulnerability. A CVSS v3.1 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).

A CVSS v4 score has also been calculated for CVE-2024-35246. A base score of 8.7 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).

3.2.3 Improper Control of Interaction Frequency CWE-799

An attacker may be able to cause a denial-of-service condition by sending many SSH packets repeatedly.

CVE-2024-32943 has been assigned to this vulnerability. A CVSS v3.1 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).

A CVSS v4 score has also been calculated for CVE-2024-32943. A base score of 8.7 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing, Transportation Systems
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Sweden

3.4 RESEARCHER

Aviv Malka and Joseph Baum of OTORIO reported these vulnerabilities to CISA.

4. MITIGATIONS

Westermo advises users to disable HTTP access to the WebGUI and instead use HTTPS instead. This change will secure the credentials and session IDs, effectively nullifying the exploits described.

To mitigate the risk of a denial-of-service attack through continuous login attempts, Westermo recommends disabling access to the device's WebGUI on external communication interfaces. For devices in production environments, disabling the WebGUI is suggested if possible.

Westermo suggests limiting access to the device's CLI on external communication interfaces to prevent SSH DOS attacks through repeated login attempts.

Westermo will keep users updated on any further enhancements.

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.
• When remote access is required, use more 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 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 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

• June 20, 2024: Initial Publication

• Westermo