Exposing Fox Tempest: A malware-signing service operation

Fox Tempest is a financially motivated threat actor operating a malware‑signing‑as‑a‑service (MSaaS) used by other cybercriminals, including Vanilla Tempest and Storm groups, to more effectively distribute malicious code, including ransomware. The post Exposing Fox Tempest: A malware-signing service operation appeared first on Microsoft Security Blog .

In this article Fox Tempest’s role and impact Fox Tempest’s malware signing as a service infrastructure Defending against Fox Tempest-enabled attacks Microsoft Defender detections Indicators of compromise Fox Tempest is a financially motivated threat actor that operates a malware-signing-as-a-service (MSaaS) used by other cybercriminals to more effectively distribute malicious code, including ransomware. The threat actor abuses Microsoft Artifact Signing to generate short-lived, fraudulent code-signing certificates to appear legitimately signed, allowing malware to evade security controls.

Fox Tempest has created over a thousand certificates and established hundreds of Azure tenants and subscriptions to support its operations. Microsoft has revoked over one thousand code signing certificates attributed to Fox Tempest.