Dns Tunneling Deep Dive
If you are interested in a more formal introduction to the DNS tunneling technique and threat tracking, you may want to check out my previous post.
Table of Contents
Getting Started
In this post, we do a deep dive into the requirements to establish a DNS tunnel also referred to as a covert channel. This topic is extensively covered. I am attempting to compiling learning and knowledge in this post to provide the technique knowledge to create a framework for established a covert channel in a custom sample. With that in mind, our goal is to establish communication between a controlled DNS zone in an authoritative server and a program. This can be later expanded to include additional evasion techniques like DNS-over-HTTPS or DNS-over-TLS, but we will start simple. If you are interested in just leveraging a tool to accomplish this goal, I would suggest checking out iodine.
Now, sense we do not care about speed, given the heuristics of this technique, we will use python for simplicity. From a meta perspective, we will need two application processes, the server and the client. You can find this posts code base here.
Setting Up the Environment
- Required tools and libraries (e.g., Python, specific DNS libraries).
- Setting up a Python virtual environment.
- Installing necessary Python packages (e.g.,
dnspython
,requests
,scapy
).
Building the Server
- Designing the server architecture.
- Code walkthrough for setting up the DNS server.
- Handling DNS queries and embedding data.
Developing the Client
- Architecture of the client-side application.
- Code for sending requests and receiving data through DNS queries.i9
- Integrating the client with the server.
Testing the Tunnel
- Steps to test the DNS tunnel.
- Monitoring and debugging techniques.
Evasion Techniques
- Introduce DNS-over-HTTPS and DNS-over-TLS.
- Discuss how these techniques can be integrated.
- Explain the advantages of using these techniques for evasion.
Security Implications and Ethical Considerations
- Discuss the ethical considerations of using DNS tunneling.
- Legal implications and potential misuse.
- How to responsibly disclose vulnerabilities.
References
Updates
- 11/17/2023: Updated Readability to post and added scaffolding for later updates.
- 11/28/2023: Added additional content sections and scaffolding
- 12/2/2023: Updated post content and removing scaffolded content