{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/products/azure-artifact-signing/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":["Fox Tempest"],"_cs_cpes":[],"_cs_cves":[],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["Azure Artifact Signing","Microsoft Teams","AnyDesk","PuTTY","Webex"],"_cs_severities":["high"],"_cs_tags":["code-signing","malware-signing","supply-chain","azure"],"_cs_type":"threat","_cs_vendors":["Microsoft","Cloudzy","AnyDesk","Webex"],"content_html":"\u003cp\u003eIn May 2026, Microsoft disrupted a malware-signing-as-a-service (MSaaS) operation run by the threat actor Fox Tempest. This operation abused the Azure Artifact Signing service (formerly Trusted Signing) to generate fraudulent code-signing certificates. These certificates were then used by cybercriminals, including ransomware gangs, to sign malware, making it appear legitimate to users and operating systems. Fox Tempest created over 1,000 certificates and hundreds of Azure tenants and subscriptions to support its operation. The service was linked to numerous malware and ransomware campaigns, including Oyster, Lumma Stealer, Vidar, Rhysida, Akira, INC, and BlackByte. The MSaaS platform was promoted on a Telegram channel named \u0026ldquo;EV Certs for Sale by SamCodeSign,\u0026rdquo; with prices ranging from $5,000 to $9,000 in Bitcoin.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eFox Tempest creates hundreds of Azure tenants and subscriptions.\u003c/li\u003e\n\u003cli\u003eThe threat actor abuses the Azure Artifact Signing service to generate short-lived (72-hour) code-signing certificates.\u003c/li\u003e\n\u003cli\u003eCybercriminal customers upload malicious files to the MSaaS platform through signspace[.]cloud or pre-configured virtual machines hosted on Cloudzy infrastructure.\u003c/li\u003e\n\u003cli\u003eFox Tempest signs the uploaded malware using the fraudulently obtained certificates.\u003c/li\u003e\n\u003cli\u003eAttackers distribute signed malware, impersonating legitimate software such as Microsoft Teams, AnyDesk, PuTTY, and Webex.\u003c/li\u003e\n\u003cli\u003eUnsuspecting victims execute the falsely named installer files.\u003c/li\u003e\n\u003cli\u003eThe installers deliver a malicious loader, which installs the fraudulently signed malware, such as Oyster.\u003c/li\u003e\n\u003cli\u003eThe malware deploys ransomware, such as Rhysida, or steals credentials and sensitive information using Lumma Stealer or Vidar.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eThe Fox Tempest MSaaS operation enabled cybercriminals to sign their malware with certificates trusted by the Windows operating system, allowing them to bypass security controls and infect systems more easily. This led to successful ransomware attacks and data theft, causing significant financial losses and reputational damage for victim organizations. Microsoft believes the operation generated millions of dollars in profits.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eBlock the domain \u003ccode\u003esignspace[.]cloud\u003c/code\u003e at the DNS resolver to prevent access to the MSaaS platform.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rules below to your SIEM to detect the execution of signed malware installers that impersonate legitimate software.\u003c/li\u003e\n\u003cli\u003eMonitor for suspicious Azure tenant and subscription creation activities that may indicate abuse of the Artifact Signing service.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-05-19T21:48:34Z","date_published":"2026-05-19T21:48:34Z","id":"https://feed.craftedsignal.io/briefs/2026-05-fox-tempest-msaas/","summary":"Microsoft disrupted a malware-signing-as-a-service (MSaaS) operation run by Fox Tempest that abused the Azure Artifact Signing service to generate fraudulent code-signing certificates, enabling malware to bypass security controls.","title":"Fox Tempest Malware-Signing-as-a-Service Disrupted","url":"https://feed.craftedsignal.io/briefs/2026-05-fox-tempest-msaas/"}],"language":"en","title":"CraftedSignal Threat Feed — Azure Artifact Signing","version":"https://jsonfeed.org/version/1.1"}