What is a QOTD reflection DDoS attack?


In the ever-evolving cyber world, it is crucial to be aware of the different types of attacks that can negatively affect online security. One such attack is the QOTD Reflection DDoS, a sneaky threat that can wreak havoc on systems and networks. In this post, we’ll explore what this type of attack is and how you can protect yourself against it.

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What is the QOTD (17/udp) service?

The QOTD (Quote of the Day Protocol) service is a service that generates a text message and was originally designed for testing and debugging purposes.
If it is accessible to the entire Internet via UDP, this service can be exploited for DDoS attacks that use amplification. This is because the attacker sends a request forging the victim’s IP and the QOTD server returns a much larger response than the request.

What is a QOTD Reflection DDoS attack?

A QOTD (Quote of the Day) reflection DDoS (Distributed Denial of Service) attack is a specific form of cyberattack. In this type of attack, attackers exploit poorly configured servers that have the QOTD protocol enabled. The QOTD protocol allows a client to request a random quote from a remote server.

The attackers send fake request packets, with a falsified destination IP address, to various QOTD-enabled servers. These servers, in turn, automatically respond with a quote to the spoofed IP address, which is actually the target of the attack.

How does the attack work?

QOTD servers automatically respond to incoming requests by sending quotes to the spoofed IP addresses that are actually the target of the attack. Attackers can amplify the traffic directed at the target, taking advantage of the response generated by misconfigured QOTD servers. This creates a large volume of response traffic that overloads the target, making it inaccessible to legitimate users.

Protect yourself against QOTD Reflection DDoS attacks:

  • Update your systems: Always keep your systems and software up to date to correct known vulnerabilities. This will help prevent attackers from exploiting poorly configured servers.
  • Disable the QOTD protocol: If you don’t need the QOTD protocol for essential operations, it is recommended that you disable it. This will reduce the attack surface and decrease the likelihood of being targeted by a QOTD reflection attack.
  • Firewalls and packet filters: Implement firewalls and packet filters to identify and block malicious traffic. These measures will help filter out spoofed packets before they reach your network.
  • DDoS mitigation services: Consider hiring specialized DDoS mitigation services. These services have the ability to detect and block DDoS attacks in real time, protecting your network against attacks, including QOTD reflection attacks.

Why should I worry about this?

QOTD can be used to cause damage to third parties, involving your network in attacks on other organizations, as well as implying higher bandwidth consumption.
Additional information on how to prevent your network from being abused for this and other DDoS attacks can be found here:

How do I fix the problem?

  • On Windows systems: Disable the feature called “simple tcp/ip services”.
  • On Unix systems: Disable the QOTD service, typically implemented via the inetd daemon.
  • On other systems or devices: If your device does not fall into any of the above categories, consult the manual to find out how to disable the service.

How can I be sure I’ve solved the problem?

You can check your server using the following commands: (preferably run them from the Internet, i.e. outside an internal network that has permission to access the server).

$ echo | nc -w 1 -u SERVIDOR_QOTD 17

Where SERVER_QOTD is the IP of the QOTD server to be tested.

QOTD Reflection DDoS attacks represent a significant threat to online security. By understanding how these attacks work and implementing appropriate protection measures, you will be one step ahead in defending against this threat. Stay vigilant, keep up to date and protect your network against QOTD reflection DDoS attacks and other cyber threats. Online security is a priority and investing in preventive measures is essential to guarantee the integrity and availability of your systems and information. By following cybersecurity best practices and remaining vigilant, you will be strengthening your defense against QOTD Reflection DDoS attacks and other constantly evolving threats. Remember that security is an ongoing responsibility and the importance of staying protected in the digital world should never be underestimated.

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