Siemens SCALANCE X Switches (Update A)

# ICS Advisory (ICSA-19-225-03) ## Siemens SCALANCE X Switches (Update A) Original release date: August 13, 2019 | Last revised: August 21, 2019 [Print Document](javascript:window.print\(\);) [Tweet](https://twitter.com/share?url=https%3A%2F%2Fus- cert.cisa.gov%2Fics%2Fadvisories%2Ficsa-19-225-03) [Like Me](https://www.facebook.com/sharer.php?u=https%3A%2F%2Fus- cert.cisa.gov%2Fics%2Fadvisories%2Ficsa-19-225-03) [Share](http://www.addthis.com/bookmark.php?url=https%3A%2F%2Fus- cert.cisa.gov%2Fics%2Fadvisories%2Ficsa-19-225-03) ### Legal Notice All information products included in [https://us-cert.gov/ics](/ics) are provided "as is" for informational purposes only. The Department of Homeland Security (DHS) does not provide any warranties of any kind regarding any information contained within. DHS does not endorse any commercial product or service, referenced in this product or otherwise. Further dissemination of this product is governed by the Traffic Light Protocol (TLP) marking in the header. For more information about TLP, see [https://www.us- cert.gov/tlp/](/tlp/). * * * ## 1\. EXECUTIVE SUMMARY * **CVSS v3 8.6** * **ATTENTION:** Exploitable remotely/low skill level to exploit * **Vendor:** Siemens * **Equipment:** SCALANCE X switches **\--------- Begin Update A Part 1 of 2 ---------** * **Vulnerability:** Insufficient Resource Pool **\--------- End Update A Part 1 of 2 ---------** ## 2\. UPDATE This updated advisory is a follow-up to the original advisory titled ICSA-19-225-03 Siemens SCALANCE X Switches that was published August 13, 2019, on the ICS webpage on us-cert.gov. ## 3\. RISK EVALUATION Successful exploitation of this vulnerability could cause a denial-of-service condition. ## 4\. TECHNICAL DETAILS ### 4.1 AFFECTED PRODUCTS The following versions of SCALANCE X switches are affected: * SCALANCE X-200: All versions * SCALANCE X-200IRT: All versions * SCALANCE X-200RNA: All versions ### 4.2 VULNERABILITY OVERVIEW **\--------- Begin Update A Part 2 of 2 ---------** #### 4.2.1 [INSUFFICIENT RESOURCE POOL CWE-410](https://cwe.mitre.org/data/definitions/410.html) **\--------- End Update A Part 2 of 2 ---------** An attacker may send large message packages repeatedly to the telnet service, which may allow a denial-of-service condition. [CVE-2019-10942](http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-10942) has been assigned to this vulnerability. A CVSS v3 base score of 8.6 has been calculated; the CVSS vector string is ([AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H](https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H)). ### 4.3 BACKGROUND * **CRITICAL INFRASTRUCTURE SECTORS:** Chemical, Critical Manufacturing, Energy, Food and Agriculture, and Water and Wastewater Systems * **COUNTRIES/AREAS DEPLOYED:** Worldwide * **COMPANY HEADQUARTERS LOCATION:** Germany ### 4.4 RESEARCHER Younes Dragoni and Alessandro Di Pinto from Nozomi Networks reported this vulnerability to Siemens. ## 5\. MITIGATIONS Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk: * Disable telnet service on affected devices. Users should use SSH instead. * Restrict network access to Port 23/TCP of the device. Siemens recommends users configure their environment according to [Siemens' operational guidelines for industrial security](https://www.siemens.com/cert/operational-guidelines-industrial- security) and follow the recommendations in the product manuals. Additional information on industrial security by Siemens can be found at: <https://www.siemens.com/industrialsecurity> For more information on the vulnerability and more detailed mitigation instructions, please see Siemens security advisory SSA-100232 at the following location: <http://www.siemens.com/cert/advisories> CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should: 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](https://www.us-cert.gov/ics/recommended-practices) on the ICS webpage on [us-cert.gov](https://www.us-cert.gov/ics). Several recommended practices are available for reading and download, including [Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies](https://www.us- cert.gov/sites/default/files/recommended_practices/NCCIC_ICS- CERT_Defense_in_Depth_2016_S508C.pdf). Additional mitigation guidance and recommended practices are publicly available on the [ICS webpage on us-cert.gov](https://www.us-cert.gov/ics) in the Technical Information Paper, [ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies](https://www.us-cert.gov/ics/tips/ICS- TIP-12-146-01B). 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. * Minimize network exposure for all control system devices and/or systems, and ensure that they are [not accessible from the Internet](https://www.us-cert.gov/ics/alerts/ICS-ALERT-10-301-01). * 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.