Leadership Hijacking in Docker Swarm and Its Consequences

With the advent of microservice-based software architectures, an increasing number of modern cloud environments and enterprises use operating system level virtualization, often referred to as containers. Docker Swarm is one of the most popular container orchestration infrastructures, providing high availability and fault tolerance. Occasionally discovered container escape vulnerabilities allow adversaries to execute code on the host operating system and operate within the cloud infrastructure. We show that docker swarm is currently not secured against misbehaving manager nodes and allows a high impact, high probability privilege escalation attack that we refer to as leadership hijacking. Cloud lateral movement and defense evasion payloads allow an adversary to leverage the docker swarm functionality to control each and every host in the underlying cluster. We demonstrate an end-to-end attack, in which an adversary with access to an application running on the cluster achieves full control of the cluster. To reduce the probability of a successful high impact attack, container orchestration infrastructures must reduce the trust level of participating nodes and in particular, incorporate adversary immune leader election algorithms.