cyberstrikeus CIS Docker Benchmark v1.7.0 - Control 5.31
Profile Applicability
- Level: 1
- Type: Manual
- Platform: Docker - Linux
Description
You should not share the host's user namespaces with containers running on it.
Rationale
User namespaces ensure that a root process inside the container will be mapped to a non-root process outside the container. Sharing the user namespaces of the host with the container does not therefore isolate users on the host from users in the containers.
Impact
None
Audit Procedure
You should run the command below and ensure that it does not return any value for UsernsMode. If it returns a value of host, it means that the host user namespace is shared with its containers.
docker ps --quiet --all | xargs docker inspect --format '{{ .Id }}: UsernsMode={{ .HostConfig.UsernsMode }}'
Remediation
You should not share user namespaces between host and containers.
For example, you should not run the command below:
docker run --rm -it --userns=host ubuntu bash
Default Value
By default, the host user namespace is shared with containers unless user namespace support is enabled.
References
- https://docs.docker.com/engine/security/userns-remap/
- https://docs.docker.com/engine/reference/commandline/run/#options
CIS Controls
v8:
- 3.12 Segment Data Processing and Storage Based on Sensitivity
- Segment data processing and storage based on the sensitivity of the data. Do not process sensitive data on enterprise assets intended for lower sensitivity data.
v7:
- 12 Boundary Defense
- Boundary Defense
v7:
- 14.1 Segment the Network Based on Sensitivity
- Segment the network based on the label or classification level of the information stored on the servers, locate all sensitive information on separated Virtual Local Area Networks (VLANs).