Sysdig's Threat Research Team uncovered a novel C2 technique called 'NATS-as-C2,' where attackers exploited a Langflow RCE vulnerability (CVE-2026-33017) to deploy a credential-harvesting botnet using NATS messaging infrastructure. The operation, dubbed KeyHunter, used NATS subject-level ACLs to coordinate distributed workers that scan cloud development environments and validate stolen AWS and AI API keys (OpenAI, Anthropic, etc.) in real time. The Go and Python workers include uTLS browser fingerprint mimicry to evade bot detection, JetStream durable queues for reliability, and systemd persistence. The attacker also attempted LLMjacking via AWS Bedrock. Detection is possible via Falco rules, and defenders should patch Langflow, restrict egress, and rotate exposed credentials.
