Now let’s investigate one of the trickiest tricks in a hacker’s playbook: DNS amplification DDoS attacks. They sound convoluted but are quite easy to understand and, really, rather disturbing. Picture it like a tiny spark hitting off a huge explosion. It’s basically what hackers do with DNS servers to inundate the targeted machine with overwhelming amounts of traffic.
No panicking! You’re not without defense here. There are ways to ensure your systems stay strong and your services stay uninterrupted. Here’s the deal, simply put.
What is a DNS Amplification Attack, Anyway?
Before we leap to the remedies, let’s unbox what we’re dealing with.
A DNS amplification attack is when a hacker sends small requests to open DNS resolvers (one could consider these to be the phonebooks of the internet) and then spoofs the target’s IP address. The DNS server sends a much larger response back to the target, thus amplifying traffic to overwhelm the system.
Knowing all that has happened now, here are ways we can stop it.
1. Close the Door on Open DNS Resolvers
The most prominent contributors to DNS amplification attacks would be open DNS resolvers-a server that will respond to any DNS queries from any client from anywhere.
What’s to be done?
Configure your DNS servers to respond to requests from a given trusted source: devices on your network. Run your DNS server software with access control, so some people could be restricted from making requests.
It sounds a lot like locking your front door and giving access only to trusted people you know.
2. Limit Response Sizes
The responses from a DNS query are large in volume, and the requests are minute, so DNS amplification attacks pack quite a punch due to this volume difference. Motivating moderation of responses is an activity to reduce attacks.
How: Configure your DNS servers so they won’t respond to queries that request vast amounts of information, or block certain queries altogether (for example, “ANY” requests).
Like just saying “yes” or “no” when asked about an encyclopedia of details.
3. Rate-Limiting
Rate limiting is a robust tool to protect your servers. It is the capacity limit on the number of requests that this server shall respond to within a time period so that these prevent your server from being flooded by attackers.
Why does it work: Even while a hacker was trying to flood your DNS server, they would still never get enough responses through to be very effective.
It’s almost like a doorman restricting a considerable number of people from coming in at one time, for the sake of preventing a riot.
4. Implement DNSSEC
DNSSEC is just that much more powerful than any layer of protection up until the check of the DNS server. It helps to verify the authenticity of DNS queries and their responses and reduces the risks of spoofing.
Bonus: While it will not directly prevent the amplification, it will, in many situations, stop the attackers from being able to falsify the DNS queries in the first place.
5. Deploy Network Firewalls and Anti-DDoS Tools
Firewalls and specialized Anti-DDoS tools can detect and filter out malicious traffic before it overwhelms your servers.
Pro tip: Many modern solutions include AI-based monitoring to identify unusual traffic patterns and respond instantly.
Consider these the neighborhood watch; they scan the visitors that come to town and deny entry to the troublemakers.
7. Collaborate with Your ISP
Your ISP can be a valuable ally in thwarting DNS amplification attacks. Many ISPs will offer services to stop spoofed traffic or limit attack traffic before it reaches your servers.
Do not hesitate to ask your ISP for protection schemes available.
Final Thoughts
DNS amplification attacks are a real danger, and they are fully manageable with the right strategies put in place. Lock your DNS servers down, use rate-limiters, and utilize DNSSEC and firewalls, turning your system into a fortress against these attacks.
Always remember, though, that it is a vicious game of cat and mouse: cyber watchers need to stay alert and monitor traffic. Always work with your team(during an incident) and with your ISP (before and during an incident). Finally, stay ahead of the attackers.
