Docker Network Hardening

Use the Docker network hardening guide to control network access. Docker security.
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.
The instructions below are for integrations and automations that use Docker (Python and PowerShell). To limit JavaScript integrations, use the advanced server configuration:
js.http.restricted
with a comma separated list of IPs/hosts to limit access to. For example:
Key
Value
js.http.restricted
169.254.169.254,localhost,127.0.0.1
The default Docker network is
bridge
and the default interface is
docker0
. To list the Docker networks, run
sudo docker network ls
on the server machine. To inspect the network properties, run
sudo docker network inspect <
network name
>
. For example:
sudo docker network bridge
.

Block Network Access to the Host Machine

Integrations and automations 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 host machine (including the Cortex XSOAR server).
  1. Add the following iptables rule for each private IP on the host 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 rage 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've 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 source.
  2. (
    Optional
    ) To view a list of all private IP addresses on the host machine, run
    sudo ifconfig -a

Block Network Access to Cloud Provider Instance Metadata

If your Cortex XSOAR Server 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.
  1. To block access from containers, add the following iptables rule:
    sudo iptables -I DOCKER-USER -i docker0 -d 169.254.169.254/32 -j DROP

Assign a Docker Network for a Docker Image

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. In Cortex XSOAR, add a server configuration to use your new Docker network to run integrations that use the
    demisto/boto3py3
    Docker image.
    Key
    Value
    python.pass.extra.keys.demisto/boto3py3
    --network=aws-metadata
  3. Reset the running containers:
    /reset_containers
  4. 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 un-trusted 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. Add a server configuration to run integrations that use the
    demisto/chromium
    docker image with the Docker network
    external
    .
    Key
    Value
    python.pass.extra.keys.demisto/chromium
    --network=external
  6. Reset the running containers:
    /reset_containers
  7. 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:

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