A DNS sinkhole, aka Blackhole DNS or sinkhole server is a Domain Name System (DNS) server that has been configured to hand out non-routable addresses for a certain set of domain names, effectively routing traffic from one DNS server to another. The DNS sinkhole can then be used to intercept DNS requests that are from known bad actors and instead of allowing access to the underlying service, reroute them into the sinkhole instead.
Devices that use the sinkhole fail to access the real site, and instead the traffic is subject to further scrutiny and analysis to reverse engineer the attack, and prevent this from happening again. All of the traffic can be re-routed, making it an effective barrier protection for many different use-cases and applications.
DNS SinkHole Usage Examples:
Malware Detection and Malicious Web Traffic Activity
When a DNS sinkhole is used to redirect traffic from a specific domain name, all requests for this domain name are forwarded to the server running the sinkhole. This can be used to detect malware infections or other malicious activity.
Blocking unwanted traffic
The DNS sinkhole method has proved to be very effective at stopping botnets by interrupting the DNS names the botnet is programmed to use, and to block e.g. unwanted ad serving sites that attempt to insert ads programmatically.
Using Filters to monitor specific suspicious activity
Instead of using a global reroute, you can also configure the sinkhole to just filter on an IP address or other variable, so that just his specific threat can be analyzed securely .
What is a dns sinkhole?
A DNS sinkhole is a method of redirecting traffic from one DNS server to another. It can be used for security purposes, such as malware detection, or for research purposes. By using a DNS sinkhole, you can direct all traffic for a given domain name to a specific server, which can then be monitored for malicious activity.
The purpose of a DNS sinkhole
A DNS sinkhole can be used for a variety of purposes, but the most common are:
Detecting and mitigating malware infections
When a DNS sinkhole is used to redirect traffic from a specific domain name, all requests for this domain name are forwarded to the server running the sinkhole. This can be used to detect malware infections or other malicious activity.
Redirecting malicious web traffic
A DNS sinkhole can also be used to redirect traffic from a specific domain name. This is most commonly used to redirect web traffic to a server with filters, which can be used to detect and block malicious activity.
Blocking unwanted traffic
You can also use a DNS sinkhole to block traffic from specific domain names. This can be used to prevent access to websites that you do not want your users to visit, or to block traffic from known botnets.
Monitoring and analyzing network traffic
You can also filter traffic and monitor various network activities. You can, for example, redirect all traffic from a specific IP address to a sinkhole and monitor it to identify related malicious traffic. By redirecting the DNS query to another server running Wireshark you will be able to analyze the captured packets and review them in more detail.
Advantage of a DNS Sinkhole:
- Can provide scalable protection with no client-side software
- Free Open Source DNS sinkholes are available, for example Pi-hole®
- Easy to install and manage a central store for all potentially malicious domains
- Proves you have pro-active management of threats in place
