OTX Threat: PCPJack Hijacked 230 AWS, GCP, and Azure Servers to Run a Hidden SMTP Relay Network

PCPJack operators compromised 230 cloud Linux servers across AWS, GCP, and Azure to build a covert SMTP relay network for email-based attacks. Researchers discovered exposed directories on infrastructure at 213.136.80[.]73 containing complete deployment toolkits including Chisel binaries, Python deployers, and operational state files. The campaign deployed Sliver C2 beacons and established reverse CVEs: CVE-2021-4034