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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2018.1534 Siemens SIMATIC S7-400 CPU 18 May 2018 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Siemens SIMATIC S7-400 CPU Publisher: ICS-CERT Operating System: Network Appliance Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2018-4850 Original Bulletin: https://ics-cert.us-cert.gov/advisories/ICSA-18-137-03 - --------------------------BEGIN INCLUDED TEXT-------------------- Advisory (ICSA-18-137-03) Siemens SIMATIC S7-400 CPU Original release date: May 17, 2018 Legal Notice All information products included in http://ics-cert.us-cert.gov 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 http://www.us-cert.gov/tlp/. - ------------------------------------------------------------------------------- 1. EXECUTIVE SUMMARY * CVSS v3 7.5 * ATTENTION: Exploitable remotely/low skill level to exploit * Vendor: Siemens * Equipment: SINAMIC S7-400 CPU * Vulnerability: Improper Input Validation 2. RISK EVALUATION Successful exploitation of this vulnerability could cause a denial-of-service condition of the CPU. The CPU will remain in DEFECT mode until a manual restart is performed. 3. TECHNICAL DETAILS 3.1 AFFECTED PRODUCTS The following versions of SIMATIC S7-400, a CPU used for process controls, are affected: * SIMATIC S7-400 (incl. F) CPU all hardware versions prior to, including, hardware V4.0, * SIMATIC S7-400 (incl. F) CPU hardware V5.0 with firmware versions prior to V5.2, and * SIMATIC S7-400H CPU all hardware versions prior to V4.5 3.2 VULNERABILITY OVERVIEW 3.2.1 IMPROPER INPUT VALIDATION CWE-20 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 be able to send a specially crafted S7 communication packet to a communication interface of the CPU. This includes Ethernet, PROFIBUS, and multi-point interfaces (MPI). No user interaction or privileges are required to exploit the security vulnerability. This vulnerability could allow causing a denial-of-service condition of the core functionality of the CPU, compromising the availability of the system. CVE-2018-4850 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). 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 Siemens ProductCERT reported this vulnerability to NCCIC. 4. MITIGATIONS Siemens has released updates for several affected products and recommends users update to the new version. * SIMATIC S7-400 (incl. F) CPU all hardware versions prior to, and including, hardware V4.0: Upgrade to hardware V5.0 or newer. https://support.industry.siemens.com/cs/ww/en/view/109483507 * SIMATIC S7-400 (incl. F) CPU hardware V5.0 with firmware versions prior to V5.2: Update to firmware V5.2 or newer. https://support.industry.siemens.com/cs/ww/en/view/109474827 * SIMATIC S7-400H CPU all hardware versions prior to V4.5: Upgrade to hardware V6.0 or newer. https://support.industry.siemens.com/cs/ww/en/view/75407031 As a general security measure, Siemens strongly recommends protecting network access to devices with appropriate mechanisms. In order to run the devices in a protected IT environment, Siemens specifically recommends users configure the environment according to Siemens? Operational Guidelines for 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 this vulnerability and associated software updates, please see Siemens security advisory SSA-914382 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. * 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 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. Additional mitigation guidance and recommended practices are publicly available on the ICS-CERT website 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 NCCIC for tracking and correlation against other incidents. No known public exploits specifically target this vulnerability. Contact Information For any questions related to this report, please contact the NCCIC at: Email: NCCICCUSTOMERSERVICE@hq.dhs.gov Toll Free: 1-888-282-0870 For industrial control systems cybersecurity information: http:// ics-cert.us-cert.gov or incident reporting: https://ics-cert.us-cert.gov/Report-Incident? - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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