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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2017.1711 Advisory (ICSA-17-187-01) Siemens OZW672 and OZW772 7 July 2017 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Siemens OZW672 and OZW772 Publisher: ICS-CERT Operating System: Network Appliance Impact/Access: Modify Arbitrary Files -- Remote/Unauthenticated Provide Misleading Information -- Remote/Unauthenticated Resolution: Mitigation CVE Names: CVE-2017-6873 CVE-2017-6872 Original Bulletin: http://ics-cert.us-cert.gov/advisories/ICSA-17-187-01 - --------------------------BEGIN INCLUDED TEXT-------------------- Advisory (ICSA-17-187-01) Siemens OZW672 and OZW772 Original release date: July 06, 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 7.4 ATTENTION: Remotely exploitable/low skill level to exploit. Vendor: Siemens Equipment: OZW672 and OZW772 Vulnerabilities: Missing Authentication AFFECTED PRODUCTS Siemens reports that the vulnerability affects the following OZW672 and OZW772 devices for monitoring building controller devices: OZW672: All versions, and OZW772: All versions. IMPACT Successful exploitation of this vulnerability could allow attackers to read and write historical measurement data under certain conditions, or to read and modify data in TLS sessions. MITIGATION Siemens recommends applying the following mitigations: Protect network access to the affected devices. Disable integrated service on Port 21/TCP in the device settings by changing the value of ACS access under Settings > Communication > Services to Off. Applying this configuration change mitigates CVE-2017-6872 entirely. Use the web portal as described in the product documentation for all applications; Connections to the web portal are not affected by CVE-2017-6873. If use of web portal is not possible, then use the integrated web server only in trusted networks. For more information on this vulnerability and more detailed mitigation instructions, please see Siemens Security Advisory SSA-563539 at the following location: http://www.siemens.com/cert/advisories (link is external) 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. No known public exploits specifically target these vulnerabilities. VULNERABILITY OVERVIEW MISSING AUTHENTICATION FOR CRITICAL FUNCTION CWE-306 An attacker with access to Port 21/TCP could access or alter historical measurement data stored on the device. CVE-2017-6872 has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N). MISSING AUTHENTICATION FOR CRITICAL FUNCTION CWE-306 A vulnerability in the integrated web server on Port 443/TCP could allow an attacker to read and manipulate data in TLS sessions while performing a man-in-the-middle (MITM) attack. CVE-2017-6873 has been assigned to this vulnerability. A CVSS v3 base score of 7.4 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N). RESEARCHER Stefan Viehbck from SEC Consult reported these vulnerabilities to Siemens. BACKGROUND Critical Infrastructure Sector: Commercial Facilities 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: http://www.auscert.org.au/render.html?cid=1980 =========================================================================== 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 iQIVAwUBWV7saYx+lLeg9Ub1AQipbRAAh2IKYUzq4qRNqM6624owcLkIrYjtke59 2R7BanPN0GJRl3uKtCgotay2yHQMj925q0bRcDqnL4o4l7ojkg6EQUerfAdBnB+c KNzKaJJN1sQe3MvLnK6SE+ekea637pQ99KMMYurelaMR/5CnIB3N06GcxyJmU8Aq F9eFLLXAcDSINLvZAu7arwuo+adoPyiMr8Ih+z1xMl1tbFgMMnmmgaNKJBD9FI/T 7wnrONXeUnh+GG6KMakVNlmQR+37LyJcebb6rIEWtlfvUeoeh0WQc3v6/XjQWijH cZ6NPAiCRArbfTKc+SWdJ2jmoxrWmoXkb1w9VG2vxIciQ/QdT7w6Ilk8C2HII2Xl y4oCKasvIwGQX22bLjkmuCyd7qUGb+vhOWbYCXSlJjYpVLnISVBuHnaNQGMUKCWN VD2JPYEsGgcjDxc4gl4bNJJyP6tHD1g9NiWk8JN7UOyqwxxZSzqEeZlOS3cAd/OJ WdBRwEKG/rogqRS3kc17MaX/ruDfzpPDah7JvgaH485oF+WoAN2Z7YHsdaaTq7pz UE15HYxxbnezOYNid0vPZdnXpN6xItuk0521F/1L8gnBxL7/mhewh9WnKcj5yRxP UL+tjbpgjdCi4um2wme4TmvlvHiN5qEVijvr2H18pTjzHPVShf4ecb5DWmSa/YCf 6mY8i1RGmJ4= =BnuU -----END PGP SIGNATURE-----