Windows 10: Deprecation of SHA-1 for SSL/TLS Certificates in Microsoft Edge & IE11

Brink · May 8, 2017

Microsoft Security Advisory 4010323

Deprecation of SHA-1 for SSL/TLS Certificates in Microsoft Edge and Internet Explorer 11
Published: May 9, 2017
Version: 1.0

Executive Summary

Beginning May 9, 2017, Microsoft released updates to Microsoft Edge and Internet Explorer 11 to block sites that are protected with a SHA-1 certificate from loading and to display an invalid certificate warning. This change will only impact SHA-1 certificates that chain to a root in the Microsoft Trusted Root Program where the end-entity certificate or the issuing intermediate uses SHA-1. Enterprise or self-signed SHA-1 certificates will not be impacted, although we recommend that all customers quickly migrate to SHA-2 based certificates. For more information, please see Windows Enforcement of SHA1 Certificates.

For more information see Microsoft Knowledge Base Article 4010323.

Advisory Details

Issue References
For more information about this issue, see the following references:

References References General Information Windows Enforcement of SHA1 Certificates SHA-1 deprecation countdown Technical Requirements Protecting Against Weak Cryptographic Algorithms
Affected Software

This advisory applies to the following operating systems:

Windows 7 Windows 7 for 32-bit Systems Service Pack 1 Windows 7 for x64-based Systems Service Pack 1 Windows Server 2008 R2 Windows Server 2008 R2 for x64-based Systems Service Pack 1 Windows Server 2008 R2 for Itanium-based Systems Service Pack 1 Windows 8.1 Windows 8.1 for 32-bit Systems Windows 8.1 for x64-based Systems Windows Server 2012 R2 Windows Server 2012 R2 Windows 10 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 Windows 10 Version 1607 for 32-bit Systems Windows 10 Version 1607 for x64-based Systems Windows Server 2016 Windows Server 2016 for x64-based Systems Server Core installation option Windows Server 2008 R2 for x64-based Systems (Server Core installation) Windows Server 2012 R2 (Server Core installation) Windows Server 2016 for x64-based Systems (Server Core installation)
Advisory FAQ

What is the scope of the advisory?
This advisory aims to assist customers in assessing the risk of certain applications that use X.509 digital certificates that are signed using the SHA-1 hashing algorithm and to recommend that administrators and certificate authorities use SHA-2 in place of SHA-1 as an algorithm for signing digital certificates.

Is this a security vulnerability that requires Microsoft to issue a security update?
No. Microsoft recommends that all customers migrate to SHA-2, and the use of SHA-1 as a hashing algorithm for signing purposes is discouraged and is no longer a best practice. Although this is not a vulnerability in a Microsoft product, Microsoft is issuing this advisory to help clarify the actual risk involved to customers.

What causes this threat?
The root cause of the problem is a known weakness of the SHA-1 hashing algorithm that exposes it to collision attacks. Such attacks could allow an attacker to generate additional certificates that have the same digital signature as an original. The use of SHA-1 certificates for specific purposes that require resistance against these attacks is discouraged. At Microsoft, the Security Development Lifecycle has required Microsoft to no longer use the SHA-1 hashing algorithm as a default in Microsoft software. For more information about SHA-1 collision weakness, see SHAttered: The first collision for full SHA-1.

What is a digital certificate?
In public key cryptography, one of the keys, known as the private key, must be kept secret. The other key, known as the public key, is intended to be shared with the world. However, there must be a way for the owner of the key to tell the world who the key belongs to. Digital certificates provide a way to do this. A digital certificate is an electronic credential used to certify the online identities of individuals, organizations, and computers. Digital certificates contain a public key packaged together with information about it - who owns it, what it can be used for, when it expires, and so forth. For more information, see Understanding Digital Certificates.

What is the purpose of a digital certificate?
Digital certificates are used primarily to verify the identity of a person or device, authenticate a service, or encrypt files. Normally, there is no need to think about certificates at all, aside from the occasional message stating that a certificate is expired or invalid. In such cases, one should follow the instructions provided in the message.

What is a certification authority (CA)?
Certification authorities are the organizations that issue certificates. They establish and verify the authenticity of public keys that belong to people or other certification authorities, and they verify the identity of a person or organization that asks for a certificate.

Suggested Actions

Review Microsoft Trusted Root Program Policy ChangesCustomers who are interested in learning more about the topic covered in this advisory should review Windows Enforcement of SHA1 Certificates.

Update from SHA-1 to SHA-2Certificate authorities have been prohibited from issuing new SHA-1 certificates Since January 2016. Customers should ensure that their certificate authorities are using the SHA-2 hashing algorithm to obtain SHA-2 certificates from their certificate authorities. To sign code with SHA-2 certificates, see the guidance on this topic at Windows Enforcement of SHA1 Certificates.
Impact of action: Older hardware-based solutions may require upgrading to support these newer technologies.

Keep Windows UpdatedAll Windows users should apply the latest Microsoft security updates to help make sure that their computers are as protected as possible. If you are not sure whether your software is up to date, visit Windows Update, scan your computer for available updates, and install any high-priority updates that are offered to you. If you have Automatic Updates enabled, the updates are delivered to you when they are released, but you have to make sure you install them.

Other Information

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 (May 9, 2017): Advisory published.

Click to expand...

Source: Microsoft Security Advisory 4010323

:)

Rob Koch · May 8, 2017

Downloading file.exe

Since this only recently started with your other Windows 10 system, I suspect that Microsoft only just finally enabled the detection of these SHA-1 signed files, quite possibly in the recent Windows 10 Anniversary update or at least the IE11 updates that
were included within it.

So if you had installed the update on one system and not the Surface Pro 4, this might explain the difference, since my own system I was using to test here is actually running Windows 8.1 and apparently has also received an update which generates that same
corrupt or invalid message you received.

Looking around, I just found another Web Developer blog article that discusses the SHA-1 deprecation roadmap. Though this doesn't specifically mention how files containing digital signatures will be handled, I suspect that the effects on SSL certificates
using SHA-1 and those for file downloads when using IE11 would be quite similar.

An update to our SHA-1 deprecation roadmap

From the comments in this and another earlier blog article I can see that even the more technically knowledgeable web developers in these discussions have questions and see potential problems with this deprecation. One of these is that older Windows XP
and Server 2003 systems don't support the new SHA-2 or other algorithms, so these will permanently break when software or web pages containing these are accessed.

So this migration from SHA-1 to SHA-2 may be far more disruptive then Microsoft expected for those with outdated software, servers and client systems.

Rob

Abi99 (2) · May 8, 2017

SHA2 support on Nikia C5,E71 and E72?

What all email accounts do we have at the moment who are operating on SHA-1?
Click to expand...

No idea about that. Most (all?) E-mail providers require SSL/TLS these days. For example, I am not able to access the POP3 servers of Microsoft without TLS.

Symantec and Comodo still offer SHA-1 certificates (when asked directly) and if your E-mail provider was clever enough, his old SHA-1 certificate is still valid. However, I am not aware of any such provider. You could setup your own server and redirect/forward
your your E-mail to that.

Consequently: If you find an E-mail provider which does not require TLS, you avoid this SHA issue (but showing your E-mail content to everyone around you). Alternatively, you try the Web interface of your E-mail provider. Again, many force forward you to
HTTPs then, again with this SHA issues.

Windows 10: Deprecation of SHA-1 for SSL/TLS Certificates in Microsoft Edge & IE11

Deprecation of SHA-1 for SSL/TLS Certificates in Microsoft Edge & IE11

Deprecation of SHA-1 for SSL/TLS Certificates in Microsoft Edge & IE11

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