How to Configure Azure Virtual Server for a WAF to Use Appdome MobileBOT™ Defense

Introduction

Web Application Firewalls (WAFs) play a crucial role in protecting web applications from a wide range of cyber threats. When combined with Appdome’s MobileBOT™ Defense solution, businesses can achieve an unparalleled level of protection for their mobile applications. This article will guide you on configuring your Azure Virtual Server to connect to a WAF so it can work seamlessly with Appdome MobileBOT™ Defense.

Before delving into the steps, let’s understand some of the terms used:

MTLS (Mutual Transport Layer Security): Mutual TLS (mTLS) is a method for mutual authentication in which both parties in a network connection validate the SSL certificates presented by each other against a trusted root Certificate Authority (CA) certificate.

Client Certificate: In cryptography, a client certificate is a type of digital certificate that is used by client systems to make authenticated requests to a remote server.

Safe Session: Represents sessions that are determined to be safe or not at risk of any threat.

At Risk Session: Represents sessions that are potentially under threat or have detected anomalies.

Header Payload: The data transferred in the header of HTTP requests or responses. Protecting this data ensures that it cannot be tampered with during transit.

Prerequisites for Using Azure Virtual Server with Appdome-Protected Apps

In order to use the Azure Virtual Server in conjunction with Appdome, you’ll need:

• A configured and accessible Azure Virtual Linux Server
• An Android or iOS app secured by Appdome MobileBOT™ Defense
• An Appdome MobileBOT™ Defense License

How to Configure the WAF to Parse Safe Session and At Risk Session

When Appdome’s code is integrated into the Azure Virtual Server, it enhances the firewall’s capability to determine the validity of a session. To categorize sessions as “Safe Session” or “At Risk Session”, Appdome’s code analyzes specific headers within incoming requests: Timestamp, Nonce, and SignedMessage. The Timestamp header allows Appdome’s code to detect potential delay attacks by comparing the request’s timestamp with the server’s time. The Nonce, a unique random value, ensures the uniqueness of each request, protecting against replay attacks. The SignedMessage, typically an RSA-encrypted SHA256 hash of the timestamp, nonce, and a shared secret, ensures the integrity of the request.

Getting Started with Azure Virtual Server Setup and Configuration

Follow these steps to configure a Linux server on GCP and Azure, and launch a Docker container with open network settings.

Note: Make sure to replace placeholders such as YOUR_VM_NAME, your-docker-image, your-username, and your-vm-ip with your own custom values and preferences.

Setting up a Linux Server on Azure

1. Create a Resource Group
   • In the Azure portal, navigate to Resource groups.
   • Create a new resource group to organize your resources.
     To learn more about managing Resource Groups on Azure, please read this article.
2. Create a Virtual Machine (VM)
   • In the Azure portal, go to Create a resource -> Compute -> Virtual machine
   • Configure your VM instance, including selecting the Linux distribution you prefer (e.g., Ubuntu, CentOS).
     Note: Make sure to allow HTTP/HTTPS traffic when configuring the firewall rules.
3. SSH into Your VM
   Use SSH to connect to your VM:

   ssh your-username@your-vm-ip

4. Running a Docker Container on Azure
   Inside your VM, install Docker:

   sudo apt-get update

To learn more, see the installation instructions for Installing Docker Engine on Ubuntu

Configure Appdome’s Docker Image

Appdome’s Docker Image is a custom solution to secure apps built on the Appdome platform with the Anti-Bot service enabled. This service functions within a Docker container based on Nginx. To facilitate its operation, users must supply an SSL certificate, config files and keys, and designated environment variables.

Prerequisites: Familiarity with Docker and UNIX-based machines is beneficial.

How Does It Work?

Based on Nginx and Lua, the service employs the Lua module to decrypt the payload and validate the signature, then it proxies the request to the target route as specified in the config file.

The module can be used with either the built-in LRU cache or with Redis, but it is recommended to use the built-in LRU to reduce the overhead of making the calls to Redis and ease the setup. If working in a cluster, it is necessary to use Redis to share storage across multiple instances.

Setup

The following environment variables are required to set up the service.

1. Receive the JSON config file

• Obtain the JSON config file from our Appdome support team. The files will be named after the taskID of that build. There may be multiple files, each corresponding to different tasks.

2. Modify the JSON config file

• Add the following fields:
  • key: The filename of the key that is relative to the /home folder in your docker container used for validation.
  • target: The endpoint to which requests are forwarded. Make sure your DNS resolver resolves this address.
  • heartbeat_validity (optional): Time in seconds for how long the heartbeat remains valid.

Example

[{

"key": "keys/your_key_file.key",

"target": "http://target_address",

"heartbeat_validity": 60

...

}]

3. Prepare the Docker Container:
– Ensure your Docker container has the necessary directories (`/home/configs` and `/home/keys`).

• Configs Directory: This directory will store JSON files containing mobile anti-bot configurations provided by Appdome.
• Keys Directory: This directory will store private keys used to validate the headers sent by Appdome.

Note: Ensure Key Matches. Verify that the key specified in the JSON config file correctly points to a key file located in the `/home/keys` directory within the Docker container.

Note: If you want to use only one config file for multiple task_ids for testing, rename the config file to default.json file and set the environment variable USE_DEFAULT=true. This setup is useful for initial testing but is not recommended for production if you regularly change the Anti-bot configuration.

4. Mount the JSON config file to the Docker Container

• Use the `docker run` command with the `-v` option to bind mount the host directories to the container directories.

By following these steps, you’ll be able to correctly set up and mount the JSON config file to your Appdome Docker container.

Optional: How to Configure SSL & mTLS

How to run Appdome Docker Image

Connect to your VM, and run the following commands:

• • Pull the docker image from our public repository:

    docker pull public.ecr.aws/n2i7f1e2/appdome-waf:1.0.6

• • Run the docker image with the following command:

    docker run -p 443:443 -p 80:80 -d \
    -v "$(pwd)"/certs:/etc/nginx/certs \
    -v "$(pwd)"/keys:/home/keys \
    -v "$(pwd)"/configs:/home/configs \
    -e REDIS=<redis address> \
    -e PASSTHROUGH=false \
    -e RESOLVER=<resolver address> \
    -e SSL_ON=true \
    -e MTLS_ON=true \
    -e FINGERPRINTS=asd, zxc, qwe \
    -e LOG_LEVEL=debug \
    --restart unless-stopped \
    public.ecr.aws/n2i7f1e2/appdome-waf:1.0.6

At this point, you have a machine that will run the Appdome Docker Image. Make sure that your application traffic is routing correctly to the Appdome Docker Image and that the Appdome Docker Image is passing the traffic correctly to the target.

Monitoring Docker Health

To ensure your Docker container is operational, it is important to configure a health check endpoint within your system’s monitoring tools. Set up an endpoint in your health monitoring system to regularly check the /_health endpoint of the Docker container. This setup helps confirm that the Docker container is running correctly and is responsive. You can use any system that supports health checks, ensuring it aligns with your deployment environment and monitoring needs.

Note: The health check only verifies that the docker is up and running, but it does not verify that the target is accessible. If you want to make sure that the connectivity between the reverse proxy and the target is working as expected, configure an additional health check that monitors the target connectivity.

Conclusion

Integrating Azure Virtual Server with Appdome provides robust protection for mobile apps. By understanding and applying the configurations above, businesses can ensure that their mobile app traffic is both secure and optimized.

Related Articles:

• MobileBOT™ Defense
• How to Configure GCP to work with Appdome MobileBOT™ Defense 
• How to Secure Android & iOS Apps in Azure DevOps Pipelines

How Do I Learn More?

If you have any questions, please send them our way at support.appdome.com or via the chat window on the Appdome platform.

Thank you!

Thanks for visiting Appdome! Our mission is to secure every app on the planet by making mobile app defense easy. We hope we’re living up to the mission with your project. If you don’t already have an account, you can sign up for free.