Siemens SIMATIC HMI Comfort Panels & SIMATIC HMI KTP Mobile Panels

1. EXECUTIVE SUMMARY

• CVSS v3 8.1
• ATTENTION: Exploitable remotely/low skill level to exploit
• Vendor: Siemens
• Equipment: SIMATIC HMI Comfort Panels, SIMATIC HMI KTP Mobile Panels 
• Vulnerability: Missing Authentication for Critical Function

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow a remote attacker to gain full access to the device(s) if the Telnet service is enabled.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of these Siemens SIMATIC HMI products, which are used for operator control and monitoring of machines and plants, are affected:

• SIMATIC HMI Comfort Panel (including SIPLUS variants): All versions before v16 Update 3a
• SIMATIC HMI KTP Mobile Panels: All versions before v16 Update 3a

3.2 VULNERABILITY OVERVIEW

3.2.1    MISSING AUTHENTICATION FOR CRITICAL FUNCTION CWE-306

Affected devices with enabled Telnet service do not require authentication for this service. This could allow a remote attacker to gain full access to the device.

CVE-2020-15798 has been assigned to this vulnerability. A CVSS v3 base score of 8.1 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing 
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Ta-Lun Yen of TXOne IoT/ICS Security Research Labs of Trend Micro, working with Trend Micro’s Zero Day Initiative, reported this vulnerability to CISA.

4. MITIGATIONS

Siemens has published a security advisory, has released updates for the affected products, and recommends users update to v16 Update 3a or a later version.

Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk:

• Disable Telnet on the HMI Panels if enabled. Note: Telnet is disabled by default.

As a general security measure, Siemens strongly recommends users protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends users configure the environment according to Siemens’ operational guidelines for Industrial Security and follow the recommendations in the product manual.

Additional information on Industrial Security by Siemens can be found at: https://www.siemens.com/industrialsecurity

For more information about this issue, please see Siemens security advisory SSA-520004

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 that VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize that 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 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.