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QUIC DDOS Attack – How does QUIC protocol work?

by | Dec 30, 2020

Need help with QUIC DDOS Attack? We can help you.

As part of our Server Management Services, we assist our customers with several DDOS queries.

Today, let us focus on the details of the QUIC DDOS Attack.


What is the QUIC protocol?

The QUIC protocol is a new way to send data over the Internet. It is faster, more efficient, and more secure than earlier protocols. QUIC is a transport protocol, which means it affects the way data travels over the Internet.

The QUIC protocol is a transport layer protocol that can replace both TCP and TLS. The latest version of the HTTP protocol, HTTP/3, runs over QUIC.

  • How does the QUIC protocol work?

For increased speed, it uses the UDP transport protocol, which is faster than TCP but less reliable. It sends several streams of data at once to make up for any data that gets lost along the way. This technique is known as multiplexing.

For better security, everything sent over QUIC will automatically encrypt. QUIC builds TLS encryption into the normal communication process. This built-in encryption speeds up the protocol. QUIC combines these two handshakes so that they happen all at once.



A QUIC flood DDoS attack is when an attacker attempts to deny service by overwhelming a targeted server with data sent over QUIC.

The victimized server has to process all the QUIC data it receives, slowing service to legitimate users. In some cases, it can crash the server altogether.

DDoS attacks over QUIC are hard to block because:

  1. It uses UDP, which provides very little information to the packet recipient that they can use to block the packets
  2. QUIC encrypts packet data so that the recipient of the data cannot easily tell if it is legitimate or not

QUIC protocol is particularly vulnerable to reflection-based DDoS attacks.

[Need help to prevent the attack? We’d be happy to assist]


What is a QUIC reflection attack?

In a reflection DDoS attack, the attacker spoofs the victim’s IP address and requests information from several servers. When the servers respond, all the information goes to the victim instead of the attacker.

With the QUIC protocol, it is possible to carry out reflection attacks using the initial “hello” message that starts a QUIC connection.

QUIC combines the UDP transport protocol with TLS encryption, the server includes its TLS certificate in its first reply to the client. This means that the server’s first message is much larger than the client’s first message.

By spoofing the victim’s IP address and sending a “hello” message to a server, the attacker tricks the server into sending large amounts of unwanted data to the victim.


Mitigate QUIC DDOS Attack

  1. Set a minimum size for the initial client hello message so that it costs the attacker considerable bandwidth to send a large amount of fake client hello messages. However, the server hello is still larger than the client hello, so an attack of this nature remains a possibility.
  2. To mitigate a DDoS attack is to implement rate-limiting.
  3. On the other hand, the use of a Web Application Firewall and anycast network diffusion will help


[Find it hard to mitigate? We can help you!]



In short, in order to prevent the attack set up and use an Anycast network, and maintain a cluster of servers. Today, we saw how our Support Engineers go about with QUIC DDOS Attack.


Never again lose customers to poor server speed! Let us help you.

Our server experts will monitor & maintain your server 24/7 so that it remains lightning fast and secure.


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