# ICS Advisory (ICSA-19-043-04) ## Siemens SIMATIC S7-300 CPU Original release date: February 12, 2019 [Print Document](javascript:window.print\(\);) [Tweet](https://twitter.com/share?url=https%3A%2F%2Fus- cert.cisa.gov%2Fics%2Fadvisories%2FICSA-19-043-04) [Like Me](https://www.facebook.com/sharer.php?u=https%3A%2F%2Fus- cert.cisa.gov%2Fics%2Fadvisories%2FICSA-19-043-04) [Share](http://www.addthis.com/bookmark.php?url=https%3A%2F%2Fus- cert.cisa.gov%2Fics%2Fadvisories%2FICSA-19-043-04) ### 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...
# ICS Advisory (ICSA-19-043-04) ## Siemens SIMATIC S7-300 CPU Original release date: February 12, 2019 [Print Document](javascript:window.print\(\);) [Tweet](https://twitter.com/share?url=https%3A%2F%2Fus- cert.cisa.gov%2Fics%2Fadvisories%2FICSA-19-043-04) [Like Me](https://www.facebook.com/sharer.php?u=https%3A%2F%2Fus- cert.cisa.gov%2Fics%2Fadvisories%2FICSA-19-043-04) [Share](http://www.addthis.com/bookmark.php?url=https%3A%2F%2Fus- cert.cisa.gov%2Fics%2Fadvisories%2FICSA-19-043-04) ### 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 7.5** * **ATTENTION** : Exploitable remotely/low skill level to exploit * **Vendor** : Siemens * **Equipment** : SIMATIC S7-300 CPU * **Vulnerability** : Improper Input Validation ## 2\. RISK EVALUATION Successful exploitation of this vulnerability could crash the device being accessed, resulting in a denial-of-service condition. ## 3\. TECHNICAL DETAILS ### 3.1 AFFECTED PRODUCTS Siemens reports the following SIMATIC S7-300 CPU product is affected: * SIMATIC S7-300 CPUs: All versions prior to v3.X.16 ### 3.2 VULNERABILITY OVERVIEW **3.2.1 [IMPROPER INPUT VALIDATION CWE-20](https://cwe.mitre.org/data/definitions/20.html)** The affected CPUs improperly validate S7 communication packets, which could cause a denial-of-service condition of the CPU. The CPU will remain in DEFECT mode until manual restart. Successful exploitation requires an attacker to send a specially crafted S7 communication packet to a communication interface of the CPU. This includes Ethernet, PROFIBUS, and Multi Point Interfaces (MPI). The vulnerability could allow a denial-of-service condition of the core functionality of the CPU. [CVE-2018-16561 ](http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2018-16561)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](https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)). ### 3.3 BACKGROUND * **CRITICAL INFRASTRUCTURE SECTORS** : Chemical, Critical Manufacturing, Energy, Food and Agriculture, Water and Wastewater Systems * **COUNTRIES/AREAS DEPLOYED** : Worldwide * **COMPANY HEADQUARTERS LOCATION** : Germany ### 3.4 RESEARCHER China Industrial Control Systems Cyber Emergency Response Team (CIC) reported this vulnerability to Siemens. ## 4\. MITIGATIONS Siemens recommends users update to Version 3.X.16, which can be downloaded from the following link: <https://support.industry.siemens.com/cs/ww/en/ps/13752/dl> Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk: * Siemens recommends operating the devices only within trusted networks 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 (<https://www.siemens.com/cert/operational-guidelines-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> For more information on this vulnerability and associated software updates, please see Siemens security advisory SSA-306710 on their website: <https://www.siemens.com/cert/advisories> NCCIC 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](/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. NCCIC reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures. NCCIC also provides a section for [control systems security recommended practices](/ics/content/recommended-practices) on the ICS-CERT web page. Several recommended practices are available for reading and download, including [Improving Industrial Control Systems Cybersecurity with Defense-in- Depth Strategies](/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-CERT website](/ics/) in the Technical Information Paper, [ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies](/ics/tips/ICS-TIP-12-146-01B). Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to NCCIC for tracking and correlation against other incidents. No known public exploits specifically target this vulnerability.
