DNS (Domain Name System), the most critical internet service and key component which allows you to connect to websites by converting the human-readable domain names to the unique IP addresses where the sites are stored. Chat services, Email services, and social networks depend on DNS to support 24/7 settling IP addresses into hostnames.
With such importance, DNS becomes one of the critical attack vectors. Without realizing this, most organizations overlooked this component when securing their infrastructure. As DNS is often found outdated, completely vulnerable, or without proper protections, DNS attacks are increasingly happening.
Here we are going to discuss DNS flood, one of the most popular DNS-based attacks, which affect your company.
Like other Internet resources, DNS is also highly prone to DDoS (Distributed Denial of Service) attacks.
DNS flooding is a symmetric DDoS attack. When a DNS server is flooded in a DDoS attack, the attack attempts to exhaust server resources with floods of IP addresses. The main goal of the DNS flood DDoS attack is to overload the victim server and make it not able to serve DNS requests since the available resources are affected by the hosted DNS zones.
To execute a DNS flood attack against a DNS server, the hacker often uses botnets to run a script from multiple servers. These scripts bombard malformed packets against a DNS service. The victim can’t distinguish which packets are from real clients and which aren’t since the attacker spoof all packet details including source IP.
This way the UDP Flood exhaust the server resources as well as the bandwidth of the victim server. The result?
When the legitimate client visits a website and he doesn’t have its IP cached, his DNS requests won’t be able to pass through due to the competing malicious requests. Because the overwhelming volume of requests exhausts the DNS server resources, it won’t have the capacity available to send him the IP address he is looking for.
Moreover, this attack is quite difficult to trace with deep analysis since each request appears legitimate.
The DNS NXDOMAIN attack is another common type of DNS Flood attack, which involves attackers sending a large volume of requests to a victim server requesting for records, which are invalid or non-existent. It results in expending the resources of the DNS server and fills the cache with invalid requests -eventually hampers the response time for legitimate requests and halting all the DNS resolution services.
If the hackers employ an abundant number of IP addresses, they can bypass most of the anomaly detection algorithms. This makes the DNS flood attack mitigation process quite difficult sometimes.
However, still, there are different approaches you can take to prevent this attack:
Conclusion
“Cybersecurity is only as strong as the weakest link” – if the weakest link is the DNS system, especially a part, which is outside your control, it is more prone to DNS flood DDoS attack. Hence, realize the risk of DNS attacks and take proactive mitigation approaches. Otherwise, you may experience the serious consequences of data theft, business disruption, or worse.
This post was last modified on February 21, 2024 10:40
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