Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2017.3020 Advisory (ICSA-17-332-01) Siemens SCALANCE W1750D, M800, and S615 29 November 2017 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Siemens SCALANCE Publisher: ICS-CERT Operating System: Network Appliance Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated Denial of Service -- Remote/Unauthenticated Resolution: Mitigation CVE Names: CVE-2017-14496 CVE-2017-14495 CVE-2017-14491 CVE-2017-13704 Original Bulletin: https://ics-cert.us-cert.gov/advisories/ICSA-17-332-01 - --------------------------BEGIN INCLUDED TEXT-------------------- Advisory (ICSA-17-332-01) Siemens SCALANCE W1750D, M800, and S615 Original release date: November 28, 2017 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/. CVSS v3 8.1 ATTENTION: Remotely exploitable/low skill level to exploit. Vendor: Siemens Equipment: SCALANCE W1750D, M800, and S615 Vulnerabilities: Resource Exhaustion, Improper Restriction of Operations within the Bounds of a Memory Buffer AFFECTED PRODUCTS The following versions of SCALANCE, network interfaces, are affected: SCALANCE W1750D: All versions, and SCALANCE M800/S615: All versions. IMPACT Successful exploitation of these vulnerabilities could allow a remote attacker to crash the DNS service or execute arbitrary code by crafting malicious DNS responses. MITIGATION Siemens reports they are preparing updates for the affected products and recommends the following mitigations until patches are available: For SCALANCE W1750D: Users who do not use the OpenDNS, Captive Portal, or URL redirection functionalities can deploy firewall rules in the device configuration to block incoming access to Port 53/UDP. For SCALANCE M800/S615: Disable DNS proxy in the device configuration (System - - DNS - DNS Proxy - Disable Checkbox for Enable DNS Proxy) and configure the connected devices in the internal network to use a different DNS server. Apply Defense-in-Depth Siemens has produced an advisory that can be found at: https://www.siemens.com/cert/pool/cert/siemens_security_advisory_ssa-689071.pdf (link is external) Siemens also reports that SCALANCE W1750D devices that are operated in controller mode on an Aruba Mobility Controller are not affected if AOS versions newer than V6.3.1.25, V6.4.4.16 V6.5.1.9, V6.5.3.3, V6.5.4.2, or 8.1.0.4 are used. NCCIC/ICS-CERT recommends that users take defensive measures to minimize the risk of exploitation of these vulnerabilities. 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. ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures. ICS-CERT 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 in the ICSCERT Technical Information Paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies, that is available for download from the ICS-CERT web site. Organizations observing any suspected malicious activity should follow their established internal procedures and report their findings to ICS-CERT for tracking and correlation against other incidents. VULNERABILITY OVERVIEW UNCONTROLLED RESOURCE CONSUMPTION ('RESOURCE EXHAUSTION') CWE-400 An attacker can cause a crash of the DNSmasq process by sending specially-crafted request messages to the service. The following CVEs have been assigned to this group of vulnerabilities: CVE-2017-13704 CVE-2017-14495 CVE-2017-14496 A CVSS v3 base score of 5.3 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L). IMPROPER RESTRICTION OF OPERATIONS WITHIN THE BOUNDS OF A MEMORY BUFFER CWE-119 An attacker can cause a crash or potentially execute arbitrary code by sending specially-crafted DNS responses to the DNSmasq process. In order to exploit this vulnerability, an attacker must be able to trigger DNS requests from the device, and must be in a position that allows the injection of malicious DNS responses. CVE-2017-14491 has been assigned to this vulnerability. A CVSS v3 base score of 8.1 has been assigned; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H). RESEARCHER Siemens Product CERT reported the vulnerabilities to ICS-CERT. BACKGROUND Critical Infrastructure Sectors: Chemical, Energy, Food and Agriculture, Healthcare and Public Health, Transportation Systems, and Water and Wastewater Systems Countries/Areas Deployed: Worldwide Company Headquarters Location: Germany Contact Information For any questions related to this report, please contact ICS-CERT at: Email: ics-cert@hq.dhs.gov (link sends e-mail) Toll Free: 1-877-776-7585 International Callers: (208) 526-0900 For industrial control systems security information and incident reporting: http://ics-cert.us-cert.gov - --------------------------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). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBWh36oYx+lLeg9Ub1AQiiaw/9ExXNqSBpz1WOwbZOFyBWpviiU7ozwQe0 RnTilEHD6RyU1EQrfaq5RJwF+w9sVKcOUJiKgQaKXyF2fZrTR72j1YBRChFYMkvv K2UIf6CGx1MoYPXjjTp/yhJcn2Ienv+jzl/owWcOGNjfu6uv15qPMG1KBT27UVHN x4gjzzPr5FwaGjeRRO6WYK1B12jbStUkOpiW2uTHORD3vpk+fxDYkDpZ7xL1kLzN G0kYx8aDGsQ0lcV6lOc6n+yb3E5F774t1r3AOJBHZjyuOEo250S86OKkz/X6a7EZ Eprob4WwzRnJE3MD/6t1tHzGFzm8re1EgFIy19Jp7idGpzW+zOu1neHKXtB7zV+c 6SvcAxEvjDWTSgrSsf6cV4PwshN+UWQlSyjHQtM3ZMuRnpYePtcaFM3a6/VhN7It pwKgcbqWNn/D+DjoegHoNzZNjZwNtYTZNrGeM1/YxmtW3vNVkVPUQuCRWaYdMV+C UGbdydAwfTaREUx3JVSwNYWnIr45DzXjLw4ZBm49x7R2JL7rFX1z7WWs2sdKntS0 N4jJ63gL0vbgkFQmZ2wIZtjSDA1TV3/B5ijDmzTJVv/5KlBAVpeJ3BSSSV/auKP0 J6dM8cN1RpQvbjeZKqZTF9DD/zuz8vsKd/NRRx//Fo2rVoJVnBQ8uwQIn+7bSFkL piLbgRxO29g= =ZBeP -----END PGP SIGNATURE-----