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.
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