5. Microsoft Will Block Compromised Certificate Monday
Approximately 10 percent of Mimecast’s customers use the compromised connection to Microsoft 365 Exchange Web Services, according to the company. Of those that do, Mimecast said current indications are that a low-single-digit number of Mimecast customers’ Microsoft 365 tenants were actually targeted.
Mimecast said it has already contacted the customers with targeted Microsoft 365 tenants to remediate the issue. The company was recently informed of the compromise by Microsoft, according to Mimecast.
Microsoft 365 customers not using Mimecast are unaffected by the compromise, according to a Microsoft spokesperson. At Mimecast’s request, Microsoft said it’s blocking the compromised Mimecast certificate on Monday, Jan. 18. Microsoft declined to answer questions from CRN about why the Redmond, Wash.-based software giant isn’t blocking the compromised certificate immediately.
