The threat actor known as PCPJack has hijacked cloud servers associated with Amazon Web Services (AWS), Google Cloud, and Microsoft Azure to create a covert SMTP email relay network. "Compromised business servers across the U.S., Europe, and Asia were quietly converted into SMTP proxies, verified for mail relay capability, and synced to a downstream consumer every five minutes," Hunt.io said in a statement. "The infrastructure was still running when we found it." The threat intelligence company said it found source code, compiled binaries, deployment state logs, internet scanners, exploitation tooling, and a live Sliver configuration after the threat actor behind the operation left two open directories on a command-and-control (C2) server ("213.136.80[.]73") without any authentication.…