Docker Network Hardening - Administrator Guide - Cortex XSIAM - Cortex - Security Operations

Cortex XSIAM Administrator Guide

Product
Cortex XSIAM
Creation date
2024-02-26
Last date published
2024-04-16
Category
Administrator Guide
Abstract

Use the Docker network hardening guide to control network access.

Docker creates its own networking stack that enables containers to communicate with other networking endpoints. You can use iptables rules to restrict which networking sources the containers communicates with. By default, Docker uses a networking configuration that allows unrestricted communication for containers, so that containers can communicate with all IP addresses.

Block Network Access to the Host Machine

Integrations and scripts running within containers do not usually require access to the host network. For added security, you can block network access from containers to services running on the engine machine.

  1. Add the following iptables rule for each private IP on the tenant machine:

    sudo iptables -I INPUT -s <IP address range> -d <host private ip address> -j DROP

    For example, to limit all source IPs from containers that use the IP ranges 172.16.0.0/12, run sudo iptables -I INPUT -s 172.16.0.0/12 -d 10.18.18.246 -j DROP. This also ensures that new Docker networks which use addresses in the IP address range of 172.16.0.0/12 are blocked from access to the host private IP. The default IP range used by Docker is 172.16.0.0/12. If you have configured a different range in Docker's daemon.json config file, use the configured range. Alternatively, you can limit specific interfaces by using the interface name, such as docker0, as a source.

  2. (Optional) To view a list of all private IP addresses on the host machine, run sudo ifconfig -a

Assign a Docker Network for a Docker Image

If your engine is installed on a cloud provider such as AWS or GCP, it is a best practice to block containers from accessing the cloud provider’s instance metadata service. The metadata service is accessed via IP address 169.254.169.254. For more information about the metadata service and the data exposed, see the AWS and GCP documentation

There are cases where you might need to provide access to the metadata service. For example, access is required when using an AWS integration that authenticates via the available role from the instance metadata service. You can create a separate Docker network, without the blocked iptable rule, to be used by the AWS integration’s Docker container. For most AWS integrations the relevant Docker image is: demisto/boto3py3

  1. Create a new Docker network by running the following command:

    sudo docker network create -d bridge -o com.docker.network.bridge.name=docker-metadata aws-metadata

  2. Edit the Engine Configuration File.

  3. Add the following key.

    "python.pass.extra.keys.demisto/boto3py3": "--network=aws-metadata"

  4. Save the changes.

  5. Restart the demisto service on the engine machine.

    sudo systemctl start d1

    (Ubuntu/DEB) sudo service d1 restart

  6. Verify the configuration of your new Docker network:

    sudo docker network inspect aws-metadata

Block Internal Network Access

In some cases, you might need to block specific integrations from accessing internal network resources and allow the integrations to access only external IP addresses. This setting is recommended for the Rasterize integration when used to Rasterize untrusted URLs or HTML content, such as those obtained via external emails. With internal network access blocked, a rendered page in the Rasterize integration cannot perform a SSRF or DNS rebind attack to access internal network resources.

  1. Create a new Docker network by running the following command:

    sudo docker network create -d bridge -o com.docker.network.bridge.name=docker-external external

  2. Block network access to the host machine for the new Docker network:

    iptables -I INPUT -i docker-external -d <host private ip> -j DROP

  3. Block network access to cloud provider instance metadata:

    sudo iptables -I DOCKER-USER -i docker-external -d 169.254.169.254/32 -j DROP

  4. Block internal network access:

    sudo iptables -I DOCKER-USER -i docker-external -d 10.0.0.0/8 -j DROP

    sudo iptables -I DOCKER-USER -i docker-external -d 172.16.0.0/12 -j DROP

    sudo iptables -I DOCKER-USER -i docker-external -d 192.168.0.0/16 -j DROP

  5. Edit the Engine Configuration File.

  6. Add the following key to run integrations that use the demisto/chromium docker image with the Docker network external.

    "python.pass.extra.keys.demisto/chromium": "--network=external"

  7. Save the changes.

  8. Restart the demisto service on the engine machine.

    sudo systemctl start d1

    (Ubuntu/DEB) sudo service d1 restart

  9. Verify the configuration of your new Docker network:

    sudo docker network inspect external

Persist Iptables Rules

By default, iptables rules are not persistent after a reboot. To ensure your changes are persistent, save the iptables rules by following the recommended configuration for your Linux operating system: