Risks

In a production environment, certain commands, paths, and files should be restricted to maintain security and stability. Commands like curl or wget can be used maliciously to download and execute unauthorized scripts, potentially compromising the entire cluster. Similarly, commands like systemctl cat kubelet or systemctl edit kubelet can expose sensitive configuration details or be used to disrupt cluster operations. Implementing strict command restrictions ensures that only authorized users can execute potentially harmful commands.

Risks of Unrestricted Command Execution

1. Unauthorized Access: Commands like curl and wget can be used to download and execute malicious code, leading to unauthorized access and control of the cluster.
2. Service Disruption: Commands such as systemctl edit kubelet can be used to alter critical service configurations, causing service disruptions and potential Denial of Service (DoS) attacks.
3. Security Breaches: Allowing unrestricted command execution can expose sensitive information and make it easier for attackers to navigate and exploit the cluster.

Best Practices for Command Restrictions

Restricting Command Execution

1. Use of Sudo for Command Execution: Only allow users to execute commands with elevated privileges using sudo. This ensures that any command requiring elevated privileges is explicitly authorized.

2. Prohibit Package Manager Commands: Disable commands that can install or update software packages, such as yum, apt-get, and zypper, to prevent unauthorized software installations.

3. Disable Download Commands: Prevent the use of commands like curl and wget to stop users from downloading files from the internet.

Limiting File Permissions

1. Restrict Read-Write Permissions: Ensure that non-admin users have read-only access to critical directories and files, preventing unauthorized modifications.

2. Enforce Least Privilege: Apply the principle of least privilege by ensuring users have only the minimum permissions necessary for their tasks.

Example Workflow for Securing Command Execution

1. Configure Sudo Access: Edit the sudoers file to allow only authorized users to execute commands with sudo.

2. Restrict Package Manager Commands: Update the sudoers file to prohibit the execution of package manager commands.

3. Disable Download Commands: Update the sudoers file to prohibit the execution of download commands.

4. Limit File Permissions: Change file and directory permissions to ensure read-only access for non-admin users.