Containers use a non-default bridge network.
Set up the docker integration.
Description
You should not use Docker’s default bridge docker0. Instead you should use Docker’s user-defined networks for container networking.
Rationale
Docker connects virtual interfaces created in bridge mode to a common bridge called docker0. This default networking model is vulnerable to ARP spoofing and MAC flooding attacks as there is no filtering applied to it.
Audit
Run this command, and verify that containers are on a user-defined network and not the default docker bridge: docker network ls --quiet | xargs docker network inspect --format '{{ .Name }}: {{ .Options }}'
You should follow the Docker documentation and set up a user-defined network. All the containers should be run in this network.
Impact
User-defined networks need to be configured and managed in line with organizational security policy.
Default value
By default, Docker runs containers within the default docker0 bridge.
References
- https://github.com/nyantec/narwhal
- https://arxiv.org/pdf/1501.02967
- https://docs.docker.com/engine/userguide/networking/
CIS controls
Version 6
9 Limitation and Control of Network Ports, Protocols, and Services
