Azure Storage TLS: Changes are coming! (…and why you care)
Published Sep 23 2020 03:05 PM 20.1K Views

Microsoft is updating Azure services in a phased manner to use TLS certificates from a different set of Certificate Authorities (CAs) beginning August 13, 2020 and concluding approximately on October 26, 2020. We expect that most Azure Storage customers will not be impacted; however, your application may be impacted if you explicitly specify a list of acceptable CAs (a practice known as “certificate pinning”)This change is limited to services in public Azure cloud and US Government cloud. There are no changes in other sovereign clouds like Azure China. 

This change is being made because the current CA certificates do not comply with one of the CA/Browser Forum Baseline requirements. This was reported on July 1, 2020 and impacts multiple popular Public Key Infrastructure (PKI) providers worldwide. Today, most of the TLS certificates used by Azure services are issued from the "Baltimore CyberTrust Root" PKI.  

Azure Storage services will remain chained to the Baltimore CyberTrust Root*, but the TLS server certificates will be issued by new Intermediate Certificate Authorities (ICAsstarting October 26, 2020. 


If any client application has pinned to an Intermediate CA rather than the Baltimore CyberTrust Root, immediate action is required to prevent disruption to connectivity to Azure Storage 


* Other Azure service TLS certificates may be issued by a different PKI. 


Certificate Renewal Summary 

The table below provides information about the certificates that are being rolled. Depending on which certificate your service uses for establishing TLS connections, action may be needed to prevent loss of connectivity.  




Post Rollover (Oct 26, 2020) 



Thumbprint: d4de20d05e66fc53fe1a50882c78db2852cae474 
Expiration: Monday, May 12, 2025, 4:59:00 PM 
Subject Name: 
CN = Baltimore CyberTrust Root 

OU = CyberTrust 
O = Baltimore 
C = IE  




Not Changing 





CN = Microsoft IT TLS CA 1 

Thumbprint: 417e225037fbfaa4f95761d5ae729e1aea7e3a42 


CN = Microsoft IT TLS CA 2 

Thumbprint: 54d9d20239080c32316ed9ff980a48988f4adf2d 


CN = Microsoft IT TLS CA 4 

Thumbprint: 8a38755d0996823fe8fa3116a277ce446eac4e99 


CN = Microsoft IT TLS CA 5 

Thumbprint: Ad898ac73df333eb60ac1f5fc6c4b2219ddb79b7 



Expiration: ‎Friday, ‎May ‎20, ‎2024 5:51:28 AM 

Subject Name:  

OU = Microsoft IT 

O = Microsoft Corporation 

L = Redmond 

S = Washington 

C = US 



CN = Microsoft RSA TLS CA 01 

Thumbprint: 703d7a8f0ebf55aaa59f98eaf4a206004eb2516a 


CN = Microsoft RSA TLS CA 02 

Thumbprint: b0c2d2d13cdd56cdaa6ab6e2c04440be4a429c75 



Expiration: ‎Tuesday, ‎October ‎8, ‎2024 12:00:00 AM;  
Subject Name:  

O = Microsoft Corporation 

C = US 


Note: Intermediate certificates are expected to change frequently. We recommend not taking dependencies on them and instead pinning the root certificate as it rolls less frequently.  


Action Required 

  1. If your client application has pinned to an Intermediate CA listed in the table, then Search your source code for the thumbprint, Common Name, and other cert properties of any of the Microsoft IT TLS CAs listed above. If there is a match, then your application will be impacted, immediate action is required:  
    1. To resolve this problem, update the source code to include the new intermediate CAs. To continue pinning intermediaries, replace the existing certificates with the new intermediates CAs: 
      1. Microsoft RSA TLS CA 01  
        (Thumbprint: 703d7a8f0ebf55aaa59f98eaf4a206004eb2516a) 
      2. Microsoft RSA TLS CA 02  
        (Thumbprint: b0c2d2d13cdd56cdaa6ab6e2c04440be4a429c75) 
    2. If you have completed the step 1.a. and need to validate your changes, we will provide a test storage account on demand for your convenience to try out before we roll these certificates in production environments. To request a test storage account, please open a support request with the options below and a member from our engineering team will get back to you. 
      • Issue Type: Technical 
      • Service: Azure Storage 
      • Problem type: Connectivity 
      • Problem subtypeDropped or terminated connections 


Additional Information 

Microsoft wide communications: To broadly notify customers, Microsoft had sent a Service Health portal notification on Aug 3rd, 2020 and released a public document that includes timelines, actions that need to be taken, and details regarding the upcoming changes to our Public Key Infrastructure (PKI). 

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‎Oct 08 2020 11:38 AM
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