Control: 3.15 Ensure that the Docker socket file ownership is set to root:docker

Description

You should verify that the Docker socket file is owned by root and group owned by docker.

The Docker daemon runs as root. The default Unix socket therefore must be owned by root. If any other user or process owns this socket, it might be possible for that nonprivileged user or process to interact with the Docker daemon. Additionally, in this case a non-privileged user or process might be able to interact with containers which is neither a secure nor desired behavior.

Additionally, the Docker installer creates a Unix group called docker. You can add users to this group, and in this case, those users would be able to read and write to the default Docker Unix socket. The membership of the docker group is tightly controlled by the system administrator. However, ff any other group owns this socket, then it might be possible for members of that group to interact with the Docker daemon. Such a group might not be as tightly controlled as the docker group. Again, this is not in line with good security practice.

For these reason, the default Docker Unix socket file should be owned by root and group owned by docker to maintain the integrity of the socket file.

Remediation

The following command could be executed:

chown root:docker /var/run/docker.sock

This sets the ownership to root and group ownership to docker for the default Docker socket file.

Default Value

By default, the ownership and group ownership for the Docker socket file is correctly set to root:docker.

Usage

Run the control in your terminal:

powerpipe control run docker_compliance.control.cis_v160_3_15

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run docker_compliance.control.cis_v160_3_15 --share

SQL

This control uses a named query:

with os_output as (
  select
    btrim(stdout_output, E' \n\r\t') as os,
    _ctx ->> 'connection_name' as os_conn
  from
    exec_command
  where
    command = 'uname -s'
), hostname as (
  select
    btrim(stdout_output, E' \n\r\t') as host,
    _ctx ->> 'connection_name' as host_conn,
    _ctx
  from
    exec_command
  where
    command = 'hostname'
),

linux_output as (
  select
    stdout_output,
    _ctx ->> 'connection_name' as conn
  from
    exec_command,
    os_output
  where
    os_conn = _ctx ->> 'connection_name'
    and os_output.os = 'Linux'
    and command = 'stat -c %U:%G /var/run/docker.sock | grep -v root:docker'
),
darwin_output as (
  select
    stdout_output,
    _ctx ->> 'connection_name' as conn
  from
    exec_command,
    os_output
  where
    os_conn = _ctx ->> 'connection_name'
    and os_output.os = 'Darwin'
    and command = 'stat -f %Su:%Sg /var/run/docker.sock | grep -v root:docker'
),
command_output as (
  select * from darwin_output
  union all
  select * from linux_output
)
select
  host as resource,
  case
    when o.stdout_output = '' then 'ok'
    else 'alarm'
  end as status,
  case
    when o.stdout_output = '' then host || ' Docker socket file ownership is set to root:docker.'
    else host || ' Docker socket file ownership is not set to root:docker.'
  end as reason
  , h._ctx ->> 'connection_name' as connection_name
from
  hostname as h,
  os_output as os,
  command_output as o
where
  os.os_conn = h.host_conn
  and h.host_conn = o.conn;

Control: 3.15 Ensure that the Docker socket file ownership is set to root:docker

Description

Remediation

Default Value

Usage

SQL

Tags