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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.3110 Advisory (icsa-21-257-10) Siemens SIPROTEC 5 relays 15 September 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Siemens SIPROTEC 5 relays Publisher: ICS-CERT Operating System: Network Appliance Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2021-33720 CVE-2021-33719 Original Bulletin: https://us-cert.cisa.gov/ics/advisories/icsa-21-257-10 - --------------------------BEGIN INCLUDED TEXT-------------------- ICS Advisory (ICSA-21-257-10) Siemens SIPROTEC 5 relays Original release date: September 14, 2021 Legal Notice All information products included in https://us-cert.cisa.gov/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://us-cert.cisa.gov/tlp/ . 1. EXECUTIVE SUMMARY o CVSS v3 9.8 o ATTENTION: Exploitable remotely/low attack complexity o Vendor: Siemens o Equipment: SIPROTEC 5 relays o Vulnerabilities: Classic Buffer Overflow 2. RISK EVALUATION Successful exploitation of these vulnerabilities could allow an attacker to cause a denial-of-service condition or trigger a remote code execution. 3. TECHNICAL DETAILS 3.1 AFFECTED PRODUCTS The following versions of SIPROTEC 5 relays are affected: o SIPROTEC 5 relays with CPU variants CP050: All versions prior to 8.80 o SIPROTEC 5 relays with CPU variants CP100: All versions prior to 8.80 o SIPROTEC 5 relays with CPU variants CP150: All versions o SIPROTEC 5 relays with CPU variants CP200: All versions o SIPROTEC 5 relays with CPU variants CP300: All versions prior to 8.80 3.2 VULNERABILITY OVERVIEW 3.2.1 BUFFER COPY WITHOUT CHECKING SIZE OF INPUT ('CLASSIC BUFFER OVERFLOW') CWE-120 An attacker can send specially crafted packets to Port 4443/TCP, which may cause a denial-of-service condition or a remote code execution. CVE-2021-33719 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:U/ C:H/I:H/A:H ). 3.2.2 BUFFER COPY WITHOUT CHECKING SIZE OF INPUT ('CLASSIC BUFFER OVERFLOW') CWE-120 An attacker can send specially crafted packets to Port 4443/TCP, which may cause a denial-of-service condition. CVE-2021-33720 has been assigned to this vulnerability. A CVSS v3 base score of 5.3 has been calculated; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:U/ C:N/I:N/A:L ). 3.3 BACKGROUND o CRITICAL INFRASTRUCTURE SECTORS: Energy o COUNTRIES/AREAS DEPLOYED: Worldwide o COMPANY HEADQUARTERS LOCATION: Germany 3.4 RESEARCHER Michael Messner from Siemens Energy reported these vulnerabilities to Siemens. 4. MITIGATIONS Siemens has released updates for the following products: o SIPROTEC 5 relays with CPU variants CP050, CP100, or CP300: Update to v8.80 or later . Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk: o Block access to Port 4443/TCP, such as with an external firewall. Siemens notes operators of critical power systems (e.g., TSOs or DSOs) worldwide are usually required by regulations to build resilience into the power grids by applying multi-level redundant secondary protection schemes. Therefore, Siemens recommends the operators check whether appropriate resilient protection measures are in place. The risk of cyber incidents impacting the grid's reliability can thus be minimized by virtue of the grid design. Siemens strongly recommends applying the provided security updates using the corresponding tooling and documented procedures made available with the product. If supported by the product, an automated means to apply the security updates across multiple product instances may be used. Siemens strongly recommends prior validation of any security update before being applied, and supervision, by trained staff, of the update process in the target environment. As a general security measure Siemens strongly recommends protecting network access with appropriate mechanisms (e.g., firewalls, segmentation, VPN) and advises to configure the environment according to their operational guidelines in order to run the devices in a protected IT environment. Additional information on industrial security by Siemens can be found at: https://www.siemens.com/industrialsecurity Please see Siemens Security Advisory SSA-847986 for more information. CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should: o Minimize network exposure for all control system devices and/or systems, and ensure that they are not accessible from the Internet . o Locate control system networks and remote devices behind firewalls, and isolate them from the business network. o When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as its 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 these vulnerabilities. For any questions related to this report, please contact the CISA at: Email: CISAservicedesk@cisa.dhs.gov Toll Free: 1-888-282-0870 CISA continuously strives to improve its products and services. You can help by choosing one of the links below to provide feedback about this product. - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. 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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). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBYUF3EuNLKJtyKPYoAQj93Q/+NeeC3Kfn2KBq5z+YjrtnyE8BWLWPdqev HpZTpHPpn6Y1XZXLR/gyeE+Swv8e8kkSIN+ZFQQhhiOLLIyUwV7jK8KMO0PkiW7H +HPQ3IfMUgQmpdrF5YQzWQTwy7B7/8wxIOuO1k5Vi40WiXVeWpvtp18kUeuL7M5w JP2duGEaBd8GP4tvJQ+WXc2JQfBRDvgbPUkrQ3v+tAIeBB6KJ1SKeONP3sgTKC3M hClU6qCYrIyVerGOKpRiEjW2BpJ+9HA71mnqf1qKKeZ0l04HLOQ2iQgzQ7bXUMFf GqABZAHxcAvnBe8G1BALcZF/MxQ+lYLFMTJTOBElmE4Uuc3jVuYrotLG0cDPFmMZ jEXCIe6sV78VzloTfsdoRHnAvL+xGCGzcNFDU2iONIJKOOdAr/lzWGJZEfGW3k9z xw0lNhuNamRYpa8m22M7b4srS5gbDo6ZqLzHRD6nV+U9PvOgd5PXsWPio4IpgmkI Dp16boMBmvM1FBqHp0126MOiY6K0pUSVOK7syaEmkfTRlgMK/GYmtdsPVzkpT6Ul IpZE2pZPCA5285zcGvWItKUVZoN2+pQiLjy79JNJ/9iieYGU6NmVA91MS60K+V7N c9ZMi9iNci/T2LaWFPQAKymkgXN82d4J+zr4owTcDti7wmVntkRp+kw4cWPFhIP5 YkmQE7nE62M= =pNUO -----END PGP SIGNATURE-----