All Docker Enterprise containers root filesystem must be mounted as read only.
An XCCDF Rule
Description
<VulnDiscussion>The container's root filesystem should be treated as a 'golden image' by using Docker run's --read-only option. This prevents any writes to the container's root filesystem at container runtime and enforces the principle of immutable infrastructure. Enabling this option forces containers at runtime to explicitly define their data writing strategy to persist or not persist their data. This also reduces security attack vectors since the container instance's filesystem cannot be tampered with or written to unless it has explicit read-write permissions on its filesystem folder and directories. Enabling --read-only at container runtime may break some container OS packages if a data writing strategy is not defined. Define what the container's data should and should not persist at runtime to determine which recommendation procedure to utilize. Example: - Enable use --tmpfs for temporary file writes to /tmp - Use Docker shared data volumes for persistent data writes By default, a container will have its root filesystem writable allowing all container processes to write files owned by the container's runtime user.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-235808r627551_rule
- Severity
- High
- References
- Updated
Remediation - Manual Procedure
Add a --read-only flag at a container's runtime to enforce the container's root filesystem to be mounted as read only.
docker run <Run arguments> --read-only <Container Image Name or ID> <Command>
Enabling the --read-only option at a container's runtime should be used by administrators to force a container's executable processes to only write container data to explicit storage locations during the container's runtime.