Microsoft shuts down illegal code-signing operation used by ransomware crims to mask their malware

Microsoft seized websites and took down hundreds of virtual machines running a cybercrime service that allegedly sold code-signing certificates to ransomware gangs, thus making their malware look like legitimate software – and allowing criminals to infect thousands of machines in the US, including at least 12 owned and operated by the Windows giant. The malware signing-as-a-service operation called Fox Tempest has been around since May 2025, and abuses Microsoft’s Artifact Signing code-signing s