Two weeks ago, email cybersecurity and email management provider Mimecast alerted customers that a certificate used to authenticate various products to Microsoft 365 Exchange Web Services had been compromised by a “sophisticated threat actor.” On Tuesday, the company posted an update to its website confirming said actor was also behind the recent hack of SolarWinds’ Orion software.

The news comes on the heels of an internal investigation Mimecast launched with the support of third-party forensics experts. Per the security update, the investigation has shown that the threat actor “accessed, and potentially exfiltrated” certain encrypted service account credentials created by users in the United States and United Kingdom.