Westermo Lynx 206-F2G

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1. EXECUTIVE SUMMARY

• CVSS v3 8.0
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Westermo
• Equipment: Lynx 206-F2G
• Vulnerabilities: Cross-site Scripting, Code Injection, Cross-Origin Resource Sharing, Cleartext Transmission of Sensitive Information, Cross-Site Request Forgery

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to access the web application, inject arbitrary code, execute malicious code, obtain sensitive information, or execute a malicious request.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Lynx 206-F2G, a layer three industrial Ethernet switch, are affected:

• Lynx: Model Version L206-F2G1
• Lynx: Firmware Version 4.24.

3.2 Vulnerability Overview

3.2.1 IMPROPER NEUTRALIZATION OF INPUT DURING WEB PAGE GENERATION ('CROSS-SITE SCRIPTING') CWE-79

An attacker with access to the web application that has the vulnerable software could introduce arbitrary JavaScript by injecting a cross-site scripting payload into the "forward.0.domain" parameter.

CVE-2023-40143 has been assigned to this vulnerability. A CVSS v3.1 base score of 5.4 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N).

3.2.2 IMPROPER NEUTRALIZATION OF INPUT DURING WEB PAGE GENERATION ('CROSS-SITE SCRIPTING') CWE-79

An attacker with access to the web application that has the vulnerable software could introduce arbitrary JavaScript by injecting a cross-site scripting payload into the "autorefresh" parameter.

CVE-2023-45222 has been assigned to this vulnerability. A CVSS v3.1 base score of 5.4 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N).

3.2.3 IMPROPER CONTROL GENERATION OF CODE ('CODE INJECTION') CWE-94

A potential attacker with access to the device would be able to execute malicious code that could affect the correct functioning of the device.

CVE-2023-45735 has been assigned to this vulnerability. A CVSS v3.1 base score of 8.0 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H).

3.2.4 CROSS-ORIGIN RESOURCE SHARING (CORS) CWE-942

A potential attacker with access to the device would be able to execute malicious code that could affect the correct functioning of the device.

CVE-2023-45213 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.5 has been calculated; the CVSS vector string is (AV:A/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N).

3.2.5 IMPROPER NEUTRALIZATION OF INPUT DURING WEB PAGE GENERATION ('CROSS-SITE SCRIPTING') CWE-79

An attacker with access to the vulnerable software could introduce arbitrary JavaScript by injecting a cross-site scripting payload into the "username" parameter in the SNMP configuration.

CVE-2023-42765 has been assigned to this vulnera or craft a malicious request.bility. A CVSS v3.1 base score of 5.4 has been calculated; the CVSS vector string is (AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N).

3.2.6 IMPROPER NEUTRALIZATION OF INPUT DURING WEB PAGE GENERATION ('CROSS-SITE SCRIPTING') CWE-319

An attacker with access to the network where the affected devices are located could maliciously actions to obtain, via a sniffer, sensitive information exchanged via TCP communications.

CVE-2023-40544 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).

3.2.7 CROSS-SITE REQUEST FORGERY (CSRF) CWE-352

The cross-site request forgery token in the request may be predictable or easily guessable allowing attackers to craft a malicious request, which could be triggered by a victim unknowingly. In a successful CSRF attack, the attacker could lead the victim user to carry out an action unintentionally.

CVE-2023-38579 has been assigned to this vulnerability. A CVSS v3.1 base score of 8.0 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H).

3.2.8 IMPROPER NEUTRALIZATION OF INPUT DURING WEB PAGE GENERATION ('CROSS-SITE SCRIPTING') CWE-79

An attacker with access to the web application with vulnerable software could introduce arbitrary JavaScript by injecting a cross-site scripting payload into the "dns.0.server" parameter.

CVE-2023-45227 has been assigned to this vulnerability. A CVSS v3.1 base score of 5.4 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Multiple
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Sweden

3.4 RESEARCHER

Aarón Flecha Menéndez, Iván Alonso Álvarez and Víctor Bello Cuevas reported these vulnerabilities to CISA.

4. MITIGATIONS

Westermo recommends following best practices for hardening, such as restricting access, disable unused services (attack surface reduction), etc., to mitigate the reported vulnerabilities.

• The reported cross-site scripting vulnerabilities will be mitigated in a future report.
• The reported cross-origin resource sharing vulnerability will be mitigated in a future report.
• The reported code injection vulnerability will be mitigated in a future report.
• The reported cross site request forgery vulnerability was patched in a later WeOS4 version.

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

• January 23,2024: Initial Publication

• Westermo