Microsoft Sharepoint and OneDrive for Business were briefly down today after a German TLS certificate was accidentally added to the main .com domains for Microsoft 365 services.
See also: Microsoft: Fixes TLS handshake failures in latest Windows update
At approximately 10:08 PM GMT yesterday, a Microsoft 365 advisory 'SP659992' warned that users may not be able to access SharePoint Online and OneDrive for Business.
“Users may have seen a certificate error when trying to access SharePoint Online and OneDrive for Business. Users may also have been unable to access or present files in Microsoft Teams,” the SP659992 bulletin states.
Microsoft resolved the issue ten minutes later, stating that the problem was caused by a recent certificate update that resulted in users receiving errors when trying to access the service.
Proposal: Microsoft fixes TLS handshake failures in out-of-band updates
However, there is more to the story, as the outage was caused by a TLS certificate *.sharepoint.de for Germany that was accidentally added to the main sharepoint.com domain.
This error caused a TLS common name mismatch error for visitors from the US and other countries to sharepoint.com and for any backend APIs or services connected to the domains, as well as for the backend APIs or services connected to the domains.
Other SharePoint users reported on Reddit and Twitter the same TLS errors, which prevented them from accessing the service.
Although it was only a short-term outage, it had a broad impact while it lasted.
For those who don't know what a TLS certificate is, Transport Layer Security is a protocol that creates an encrypted session between two computers on the Internet. It verifies the identity of the server and prevents hackers from intercepting any data.
Read also: Russia creates its own TLS certificate authority to bypass sanctions
source of information:bleepingcomputer.com
