cyberstrikeus Ensure containers are restricted from acquiring new privileges (Manual)
Profile Applicability
• Level 1 - Docker - Linux
Description
By default you should restrict containers from acquiring additional privileges via suid or sgid.
Rationale
A process can set the no_new_priv bit in the kernel and this persists across forks, clones and execve. The no_new_priv bit ensures that the process and its child processes do not gain any additional privileges via suid or sgid bits. This reduces the security risks associated with many dangerous operations because there is a much reduced ability to subvert privileged binaries.
Setting this at the daemon level ensures that by default all new containers are restricted from acquiring new privileges.
Impact
no_new_priv prevents LSMs such as SELinux from escalating the privileges of individual containers.
Audit Procedure
To confirm this setting, you should review the dockerd start-up options and a check of any settings in /etc/docker/daemon.json should also be carried out.
To review the dockerd startup options, the following command can be used:
ps -ef | grep dockerd
You should ensure that the --no-new-privileges parameter is present and that it is not set to false.
The contents of /etc/docker/daemon.json should also be reviewed.
Remediation
You should run the Docker daemon as below:
dockerd --no-new-privileges
Default Value
By default, containers are not restricted from acquiring new privileges.
References
- https://docs.docker.com/engine/reference/commandline/dockerd/
- https://github.com/moby/moby/pull/20727
CIS Controls
Controls Version: v8
Control: 6.1 Establish an Access Granting Process
Establish and follow a process, preferably automated, for granting access to enterprise assets upon new hire, rights grant, or role change of a user.
IG 1: ● IG 2: ● IG 3: ●
Controls Version: v7
Control: 4 Controlled Use of Administrative Privileges
Controlled Use of Administrative Privileges