DNS Flood Attack

DNS Flood Attack is a type of DDoS attack that is known to disrupt the DNS resolution of the affected domain. DNS Flood attacks are prevalent and also very dangerous for any domain. Here is what you need to learn about DNS flood attack.

What is a DNS flood attack?

DNS refers to Domain Name System. DNS servers have similar functions to “phonebooks,” i.e., they provide a path through which internet-connected devices can lookup specific web servers so they can access content on the internet.

A DNS attack, on the other hand, is a type of distributed denial of service attack (DDoS) where the DNS servers of a particular domain are flooded by the attacker. The DNS resolution of that domain is affected by the DNS flood attack. And this way, the website, API, or the web application will get compromised and would lose the ability to respond to legitimate traffic.

It is difficult to take action against a DNS flood attack because the traffic often comes from a multitude of unique sources. It is tough to identify if the incoming traffic is legitimate, or is it just a part of the DNS attack.

How does a DNS flood attack work?

The Domain Name System is essential for any website as it is the entity that translates between easy to remember names (for instance example.com) and the hard to remember addresses of website servers (for instance 192.168.0.1). Once the DNS attack happens, it makes its infrastructure unusable for most people.

DNS flood attacks have been on the rise recently because of the availability of high bandwidth Internet of Things (IoT) botnets, i.e., Mirai. DNS flood attacks often use high bandwidth IoT devices, such as DVR boxes, IP cameras, and other devices, in order to overwhelm the DNS provider’s services. This stops any legitimate users from accessing the services offered by the DNS servers.

There is one thing that you should take note of. DNS flood attacks are actually different from DNS amplification attacks. Unlike the DNS flood attack, a DNS amplification attack reflects and amplifies any traffic coming off unsecure DNS servers. This hides the origin of the attack and can increase its overall effectiveness.

A DNS amplification attack can use devices that have smaller bandwidth connections. These are then used to make numerous requests to any unsecure DNS servers. These devices then make small requests for very large DNS records. However, when the requests are made, the attacker forges the return address to that of the intended victim. This amplification method allows the attacker to take out large targets even if he has limited attack resources.

How can a DNS Flood attack be mitigated?

This DNS attack method is different than the traditional amplification-based attack methods. In the modern age, it is easy to get hold of high bandwidth botnets. This allows attackers to target large organizations easily.

The permanent solution to this threat is to update and replace any IoT devices that have been compromised are used for DNS attacks. Until that happens, a solution to this problem is for organizations to use a very large and highly distributed DNS system with the capability to monitor, absorb, and block all attack traffic in real-time.