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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.3107 Advisory (icsa-21-257-07) Siemens APOGEE and TALON 15 September 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Siemens APOGEE Siemens TALON Publisher: ICS-CERT Operating System: Network Appliance Impact/Access: Root Compromise -- Remote/Unauthenticated Execute Arbitrary Code/Commands -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2021-27391 Original Bulletin: https://us-cert.cisa.gov/ics/advisories/icsa-21-257-07 - --------------------------BEGIN INCLUDED TEXT-------------------- ICS Advisory (ICSA-21-257-07) Siemens APOGEE and TALON 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: APOGEE and TALON o Vulnerability: Classic Buffer Overflow 2. RISK EVALUATION Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the device with root privileges. 3. TECHNICAL DETAILS 3.1 AFFECTED PRODUCTS The following products are affected: o APOGEE MBC (PPC) (P2 Ethernet): v2.6.3 and newer o APOGEE MEC (PPC) (P2 Ethernet): v2.6.3 and newer o APOGEE PXC Compact (BACnet): All versions prior to v3.5.3 o APOGEE PXC Compact (P2 Ethernet): v2.8 and newer o APOGEE PXC Modular (BACnet): All versions prior to v3.5.3 o APOGEE PXC Modular (P2 Ethernet): v2.8 and newer o TALON TC Compact (BACnet): All versions prior to v3.5.3 o TALON TC Modular (BACnet): All versions prior to v3.5.3 3.2 VULNERABILITY OVERVIEW 3.2.1 BUFFER COPY WITHOUT CHECKING SIZE OF INPUT ('CLASSIC BUFFER OVERFLOW') CWE-120 The web server of affected devices lacks proper bounds checking when parsing specific requests, which could lead to a buffer overflow. An unauthenticated remote attacker could exploit this vulnerability to execute arbitrary code on the device with root privileges. CVE-2021-27391 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 ). 3.3 BACKGROUND o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing o COUNTRIES/AREAS DEPLOYED: Worldwide o COMPANY HEADQUARTERS LOCATION: Germany 3.4 RESEARCHER Paul Noalhyt and David Doggett from Red Balloon Security reported this vulnerability to Siemens. 4. MITIGATIONS Siemens recommends updating the following products to v3.5.3 or later (login required): o APOGEE PXC Compact (BACnet) o APOGEE PXC Modular (BACnet) o TALON TC Compact (BACnet) o TALON TC Modular (BACnet) For products not listed above Siemens has recommended the following workarounds and mitigations: o Contact a Siemens office for support. o Restrict access to the device, especially to the web interface. 80/TCP and 443/TCP should only be connected to trusted IP addresses. o Disable the integrated web server. As a general security measure, Siemens strongly recommends protecting network access to affected products with appropriate mechanisms. It is advised to follow recommended security practices to run the devices in a protected IT environment. For more information see Siemens Security Advisory SSA-944498 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 this vulnerability. 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. 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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