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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2016.0090 Update to Improve TLS Session Resumption Interoperability 13 January 2016 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Microsoft Windows Publisher: Microsoft Operating System: Windows Impact/Access: Reduced Security -- Remote with User Interaction Resolution: Patch/Upgrade Original Bulletin: https://technet.microsoft.com/en-us/library/security/3109853 - --------------------------BEGIN INCLUDED TEXT-------------------- Microsoft Security Advisory 3109853 Update to Improve TLS Session Resumption Interoperability Published: January 12, 2016 Version: 1.0 Executive Summary Microsoft is announcing the availability of an update to improve interoperability between Schannel-based TLS clients and 3rd-party TLS servers that enable RFC5077-based resumption and that send the NewSessionTicket message in the abbreviated TLS handshake. The update addresses an issue in schannel.dll that could cause RFC5077 session ticket-based resumption to fail and subsequently cause WinInet-based clients (for example, Internet Explorer and Microsoft Edge) to perform a fallback to a lower TLS protocol version than the one that would have been negotiated otherwise. This improvement is part of ongoing efforts to bolster the effectiveness of encryption in Windows. For additional details and deployment guidance, see Microsoft Knowledge Base Article 3109853. Affected Software Operating System Windows 8 for 32-bit Systems Windows 8 for x64-based Systems Windows 8.1 for 32-bit Systems Windows 8.1 for x64-based Systems Windows Server 2012 Windows Server 2012 R2 Windows RT Windows RT 8.1 Windows 10 for 32-bit Systems Windows 10 for x64-based Systems Windows 10 Version 1511 for 32-bit Systems Windows 10 Version 1511 for x64-based Systems Server Core installation option Windows Server 2012 (Server Core installation) Windows Server 2012 R2 (Server Core installation) Advisory FAQ What is the scope of the advisory? To announce the availability of an update to improve interoperability between Schannel-based TLS clients and 3rd-party TLS servers that enable RFC5077-based resumption and that send the NewSessionTicket message in the abbreviated TLS handshake. Is this a security issue? No. This is a compliance issue regarding Schannel's implementation of RFC 5077 and is causing interoperability issues. What does the update do? The update addresses an issue in schannel.dll that could cause RFC5077 session ticket-based resumption to fail and subsequently cause WinInet-based clients (for example, Internet Explorer and Microsoft Edge) to perform a fallback to a lower TLS protocol version than the one that would have been negotiated otherwise. Acknowledgments Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgments for more information. Other Information Microsoft Active Protections Program (MAPP) To improve security protections for customers, Microsoft provides vulnerability information to major security software providers in advance of each monthly security update release. Security software providers can then use this vulnerability information to provide updated protections to customers via their security software or devices, such as antivirus, network-based intrusion detection systems, or host-based intrusion prevention systems. To determine whether active protections are available from security software providers, please visit the active protections websites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners. Feedback You can provide feedback by completing the Microsoft Help and Support form, Customer Service Contact Us. Support Customers in the United States and Canada can receive technical support from Security Support. For more information, see Microsoft Help and Support. International customers can receive support from their local Microsoft subsidiaries. For more information, see International Support. Microsoft TechNet Security provides additional information about security in Microsoft products. Disclaimer The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply. Revisions V1.0 (January 12, 2016): Advisory published. - --------------------------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 iQIVAwUBVpW3TH6ZAP0PgtI9AQIIXRAAnNFN3V9M7lN5Ucms+FXxAQ1JNrhtXsWo ilA8YPkI5OyD0uB9VuAyZ6aS66vevEUmMlpS6IzO7qbOoJx6lPUKDNrtRBvY9zDf 9FyvF283EoUa/Qv8CthRTnvIcAHhPtogzqXK/N1ozCnaGL+dR/S26zMUosAORWs6 2c8SKYkmmPWJN7NkjTZ6UPEWpPoLu7HetzTuYmZS9D8Jl6NwBh3ey6SFXCpokQVR M39wgwjf8ErSOzEVdmz8nzdDCUE22+yUtLg2eEKCjjjHwaXRMFuNAplZBmOZs1YZ VzroFuGl9J5CYLaKKbRDCw5PwakQKQjaTzPLuHQm3AOk++IJDgp13GYp4ZnlMrHv Pf251bqkN3YYVKpHydd0fyWZo6NZsftDe9BY+rY1WDgbXPpTKD17ijaVQa+1UN+I 4CiVpB36gFI6GF1jtNpUr1qV8fJdycZjAzoOs7WoIhjQbMkl2I8J+OvcRvGyQybA SX3+trApmbdOqLaoaMV27JOkbo03qRS7dumHHxPaUdKKx8/SLdysVUt9PY/Rno1e FMoTCHdmLHr7QcupaTbRWJaFom8fX7V9/1dIotW77ddbEuhnE7WPwqsk3cElVrkR DdABinUovMREdPg2ORv6E4jdVJx6bNpjNndCyWxUs6r7wuX/AYIBny4ccr+dRAY5 O5D0GXJmas8= =fbyO -----END PGP SIGNATURE-----