Measures

To secure your Kubernetes production environment, follow these best practices for command restrictions and file permission management:

Restrict Command Execution:

Ensure that only authorized users can execute critical commands by controlling access to potentially harmful or disruptive commands. Implement the following measures:

Use of Sudo for Command Execution:

Limit the execution of commands requiring elevated privileges to authorized users only through the use of sudo. This ensures that users must be explicitly authorized to run certain commands, reducing the risk of unauthorized actions.

Action: Edit the /etc/sudoers file to restrict which users can execute privileged commands with sudo.

# Example to allow user 'admin' to execute only specific commands

admin ALL=(ALL) NOPASSWD: /bin/systemctl, /bin/journalctl

Prohibit Package Manager Commands:

Disable commands that allow users to install or update software packages (e.g., yum, apt-get, zypper). This prevents unauthorized users from installing or modifying software within the environment.

Action: Add rules to the sudoers file to block package management commands for non-admin users:

# Deny package manager commands for all non-admin users

%non-admin-users ALL=(ALL) !/usr/bin/apt-get, !/usr/bin/yum, !/usr/bin/zipper

Disable Download Commands:

Restrict the execution of commands like curl, wget, and other similar tools that can be used to download files from the internet. This prevents users from introducing potentially harmful scripts or executables into the cluster.

Action: Add restrictions to the sudoers file or use security tools (such as AppArmor or SELinux) to block the execution of these commands for unauthorized users:

# Prohibit curl and wget for all non-admin users

%non-admin-users ALL=(ALL) !/usr/bin/curl, !/usr/bin/wget

Limit File Permissions:

Control access to critical system files and directories by setting strict file permissions. This ensures that only authorized users can modify or view sensitive files.

Restrict Read-Write Permissions:

Ensure that non-admin users have read-only access to critical directories and files, preventing unauthorized modifications. For example, restrict access to configuration files, logs, and sensitive system directories.

Action: Use chmod and chown to apply appropriate permissions:

chmod 600 /etc/kubernetes/config

chown root:root /etc/kubernetes/config

This ensures that only root or authorized users can modify these critical files.

Enforce Least Privilege:

Apply the principle of least privilege by assigning minimal permissions to users based on their roles. Only give users access to the commands and files necessary to perform their tasks, reducing the potential for unauthorized actions.

Action: Implement RBAC (Role-Based Access Control) in Kubernetes to control user access to resources. Use tools like chown and chmod to manage file permissions.

Example Workflow for Securing Command Execution and File Permissions:

Configure Sudo Access:

Edit the /etc/sudoers file to ensure that only authorized users can execute privileged commands, such as package management or system control commands. Deny access to dangerous commands (e.g., curl, wget) for non-admin users.

Restrict Package Manager Commands:

Add explicit restrictions in the sudoers file to prevent non-admin users from executing package management commands such as apt-get, yum, or zypper.

Disable Download Commands:

Prevent non-admin users from executing commands like curl and wget to download files from the internet. This helps prevent the introduction of malicious files into the cluster.

Limit File Permissions:

Apply strict file permissions to critical system files and directories using chmod and chown. Ensure that only authorized users have read-write access to sensitive configuration files and directories.

Enforce Least Privilege:

Regularly audit user permissions to ensure compliance with the principle of least privilege. Use RBAC in Kubernetes and ensure minimal file access for non-admin users.

By implementing these best practices, you can prevent unauthorized command execution, protect critical system files, and minimize the risk of service disruptions and security breaches in your Kubernetes environment.