Fox Tempest is a financially motivated threat actor providing malware-signing-as-a-service (MSaaS) to the cybercrime ecosystem. By abusing Microsoft Artifact Signing via stolen identities, they generate short-lived, fraudulent code-signing certificates that allow threat actors like Vanilla Tempest to bypass security controls and deploy payloads such as the Oyster backdoor and Rhysida ransomware.
Oyster Backdoor
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Exposing Fox Tempest: A malware-signing service operation