Siemens SIMATIC WinAC RTX (F) 2010 (Update A)

1. EXECUTIVE SUMMARY

• CVSS v3 7.5 *ATTENTION: Exploitable remotely/low skill level to exploit
• **Vendor:**Siemens
• Equipment: SIMATIC WinAC RTX (F) 2010

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• Vulnerability: Insufficient Resource Pool

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2. UPDATE INFORMATION

This updated advisory is a follow-up to the original advisory titled ICSA-19-281-03 Siemens SIMATIC WinAC RTX (F) 2010 that was published October 8, 2019, on the ICS webpage on us-cert.gov.

3. RISK EVALUATION

Successful exploitation of this vulnerability could allow an attacker to perform a denial-of-service attack that could compromise the availability of the service provided by the software.

4. TECHNICAL DETAILS

4.1 AFFECTED PRODUCTS

The following versions of Siemens SIMATIC WinAC RTX (F) 2010, software controller for PC-based automation solutions, are affected:

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• SIMATIC WinAC RTX (F) 2010 all versions prior to SP3 Update 1

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4.2 VULNERABILITY OVERVIEW

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4.2.1 INSUFFICIENT RESOURCE POOL CWE-410

An unauthenticated attacker sending a large HTTP request to the host where WinAC RTX is running may trigger a denial-of-service condition.

CVE-2019-13921 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).

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4.3 BACKGROUND

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

4.4 RESEARCHER

Tal Keren from Claroty reported this vulnerability to Siemens.

5. MITIGATIONS

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Siemens recommends installing the following software update to address this vulnerability:

• Update to SIMATIC WinAC RTX (F) 2010: SP3 Update 1

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

• Restrict network access to the host containing the affected service.
• If the service is not used as a server, configure Windows Firewall to disable communications on the port of the vulnerable service.

As a general security measure, Siemens strongly recommends protecting network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens’ operational guidelines for Industrial Security, and following the recommendations in the product manuals.

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

For more information on this vulnerability and more detailed mitigation instructions, please see Siemens security advisory SSA-878278 at the following location: <http://www.siemens.com/cert/advisories&gt;

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.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.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.