Docker hardening guide - Use the Docker Hardening Guide to configure the Cortex Cloud settings when running Docker containers. - Administrator Guide - Cortex XSIAM - Cortex CLOUD - Cortex

Docker hardening guide - Use the Docker Hardening Guide to configure the Cortex Cloud settings when running Docker containers. - Administrator Guide - Cortex XSIAM - Cortex CLOUD - Cortex - Security Operations

Cortex Cloud Posture Management Documentation

Product

Cortex Cloud Application Security > Cortex CLOUD

License

Cloud Posture Management

Creation date

2025-01-22

Last date published

2026-06-10

Tip

We recommend reviewing Docker network hardening below before changing any parameters in the configuration file.

To securely run Docker containers, we recommend using the latest Docker version.

You can Check Docker Hardening Configurations to verify that the Docker container has been hardened according to the settings we recommend.

Note

The settings below can also be applied to Podman, with the exception of limiting available memory, limiting available CPU, and limiting PIDS.

Docker creates its networking stack that enables containers to communicate with other networking endpoints. You can use iptables rules to restrict which networking sources the containers communicate 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.
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 that 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 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.
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
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 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 either by editing the d1.conf file, or If you installed via Shell, you can edit the configuration in the UI as well as editing the file directly. For details, see Configure engines.
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) 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. We recommend this setting 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 an 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 either by editing the d1.conf file, or If you installed via Shell, you can edit the configuration in the UI as well as editing the file directly. For details, see Configure engines.
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) 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:
- Ubuntu
- Red Hat and related operating system flavors

You can apply more specific fine tuned settings to Docker images, according to the Docker image name or the Docker image name including the image tag. To apply settings to a Docker image name, add the advanced configuration key to the engine configuration file. If you apply Docker image specific settings, they will be used instead of the general python.pass.extra.keys setting. This overrides the general memory and CPU settings, as needed.

Edit the engine configuration file either by editing the d1.conf file, or If you installed via Shell, you can edit the configuration in the UI as well as editing the file directly. For details, see Configure engines.
Add the following key to apply settings to a Docker image name.
"python.pass.extra.keys.<image_name>"
For example, "python.pass.extra.keys.demisto/dl".
- To apply settings to a Docker image name, including the image tag, use "python.pass.extra.keys.<image_name>": "<image_tag>".
  For example, "python.pass.extra.keys.demisto/dl": "1.4".
- To set the Docker images demisto/dl (all tags) to use a higher max memory value of 2g and to remain with the recommended PIDs and ulimit, add the following to the configuration file:"python.pass.extra.keys.demisto/dl": "--memory=2g##--ulimit=no- file=1024:8192##--pids-limit=256"
Save the changes.
Restart the demisto service on the engine machine.
sudo systemctl start d1
(Ubuntu) sudo service d1 restart

For additional security isolation, we recommend to run Docker containers as non-root internal users. This follows the principle of least privilege.

Edit the engine configuration file either by editing the d1.conf file, or If you installed via Shell, you can edit the configuration in the UI as well as editing the file directly. For details, see Configure engines.
Add the following key:
"docker.run.internal.asuser": true
For containers that do not support non-root internal users, add the following key:
"docker.run.internal.asuser.ignore" : "A comma separated list of container names. The engine matches the container names according to the prefixes of the key values>"
For example, "docker.run.internal.asuser.ignore"="demisto/python3:","demisto/python:"
The engine matches the key values for the following containers:
```
demisto/python:1.3-alpine
demisto/python:2.7.16.373
demisto/python3:3.7.3.928
demisto/python3:3.7.4.977
```
The : character should be used to limit the match to the full name of the container. For example, using the : character does not find demisto/python-ubuntu:2.7.16.373.
Save the changes.
Restart the demisto service on the engine machine.
sudo systemctl start d1
(Ubuntu) sudo service d1 restart

When a container exceeds the specified amount of memory, the container starts to swap. Not all Linux distributions have the swap limit support enabled by default.

Red Hat distributions usually have swap limit support enabled by default.
Ubuntu distributions usually have swap limit support disabled by default.

To protect the host from a container using too many system resources (either because of a software bug or a DoS attack), limit the resources available for each container. In the engine configuration file, some of these settings are set using the advanced parameter: python.pass.extra.keys. This key receives as a parameter full docker run options, separated with the ## string.

How to check if your system supports swap limit capabilities

On the engine machine, run the following command:
sudo docker run --rm -it --memory=1g demisto/python:1.3-alpine true
If swap limit capabilities is enabled, configure the memory limitation . (To test the memory, see step 5 of configure the memory limitation.)Docker hardening guideDocker hardening guide
If you see the following message in the output (the message may vary between Docker versions):
WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
You have 2 options:
- Configure swap limit capabilities by following the Docker documentation.
- See How to configure the memory limit support without swap limit capabilities.
If you see the WARNING: No swap limit support you can configure memory support without swap limit capabilities.

How to configure the memory limit support without swap limit capabilities

Edit the engine configuration file either by editing the d1.conf file, or If you installed via Shell, you can edit the configuration in the UI as well as editing the file directly. For details, see Configure engines.
Add the following key to disable swap memory enforcement:
"python.pass.extra.keys": "--memory=1g##--memory-swap=-1"
If you have the python.pass.extra.keys already set up with a value, add the value after the ## separator.
Save the changes.
Restart the demisto service on the engine machine.
sudo systemctl start d1
(Ubuntu) sudo service d1 restart

We recommend limiting available memory for each container to 1 GB.

If swap limit capabilities is enabled (see How to check if your system supports swap limit capabilities above), in Cortex Cloud configure the memory limitation using the following advanced parameters.

Edit the engine configuration file either by editing the d1.conf file, or If you installed via Shell, you can edit the configuration in the UI as well as editing the file directly. For details, see Configure engines.
Add the following keys.
"limit.docker.memory": true, "docker.memory.limit": "1g"
Note
If you do not want to apply Docker memory limitations, you should explicitly set the advanced parameter: limit.docker.memory to false.
Save the changes.
Restart the demisto service on the engine machine.
sudo systemctl start d1
(Ubuntu) sudo service d1 restart

Test the memory limit.

In the Script Name file, type TestMemory.

Add the following script:

from multiprocessing import Process
import os


def big_string(size):
    sys.stdin = os.fdopen(0, "r")
    s = 'a' * 1024
    while len(s) < size:
        s = s * 2
    print('completed creating string of length: {}'.format(len(s)))


size = 1 * 1024 * 1024 * 1024
p = Process(target=big_string, args=(size, ))
p.start()
p.join()
if p.exitcode != 0:
    return_error("Return code from sub process indicates failure: {}".format(p.exitcode))
else:
    print("Success allocating memory of size: {}".format(size))

In the SCRIPT SETTINGS section, select the script to run on the Single engine and select the engine where you want to run the script.
Save the script.
To test the memory limit, type !TestMemory. The command returns an error when it fails to allocate 1 GB of memory.

Set the advanced parameters to configure the CPU limit, PIDs limit, and the open file descriptor limit.

Edit the engine configuration file either by editing the d1.conf file, or If you installed via Shell, you can edit the configuration in the UI as well as editing the file directly. For details, see Configure engines.

Add the following keys:

Parameter	Key
Available CPU limit	`"limit.docker.cpu": true, "docker.cpu.limit": "<CPU Limit>"` We recommend to limit each container to 1 CPU. (For example, `1.0`. Default is 1.0).
PIDs limit	`"python.pass.extra.keys": "--pids-limit=256"`
Open file descriptors limit	`"python.pass.extra.keys": "--ulimit=nofile=1024:8192"`

Save the changes.
Restart the demisto service on the engine machine.
sudo systemctl start d1
(Ubuntu) sudo service d1 restart

Check your Docker hardening configurations on an engine by running the !DockerHardeningCheck command in the Case/Issue War Room CLI. The results show the following:

Non-root User
Memory
File descriptors
CPUs
PIDs

Before running the command, ensure that your engine is up and running.

Update the DockerHardeningCheck script to run on the engine.
1. Go to Investigation & Response → Automation → Scripts → DockerHardeningCheck → Settings.
2. In the Run on field select Single engine and from the list, select the engine you want to run the script.
3. Save the script.
Verify the Docker container has been hardened according to recommended settings. In the Case/Issue War Room CLI, run the !DockerHardeningCheck command.