Hackers Steal Mimecast Certificate Used to Securely Connect with Microsoft 365

Mimecast said on Tuesday that “a sophisticated threat actor” had compromised a digital certificate it provided to certain customers to securely connect its products to Microsoft 365 (M365) Exchange.
The discovery was made after the breach was notified by Microsoft, the London-based company said in an alert posted on its website, adding it’s reached out to the impacted organizations to remediate