Cloudflare has mitigated a record-breaking HTTPS DDoS attack, an internet infrastructure company said on Tuesday.
The incident occurred last week and was aimed at one of Cloudflare's customers. Using breached servers and virtual machines the threat actor sent 26 million request per second to a victim’s website, which makes the attack the largest HTTPS DDoS attack ever recorded.
According to Cloudflare, the attack originated from a small but powerful botnet of 5,067 devices. On average, each bot generated approximately 5,200 requests per second at peak. Thanks to the use of breached servers and virtual machines, the botnet is 4 thousand times more powerful than the botnet of 730,000 IoT devices. This larger botnet, which was observed by Cloudflare earlier, generated less than one million requests per second, i.e. roughly 1.3 requests per second on average per device.
Within less than 30 seconds, the botnet generated more than 212 million HTTPS requests from over 1,500 networks in 121 countries, including Indonesia, the United States, Brazil and Russia. About 3% of the attack came through Tor nodes.
HTTPS DDoS attacks are more expensive, said the experts. To conduct this type of attack a threat actor needs a lot of computational resources because establishing a secure TLS encrypted connection isn’t cheap. That’s why it costs the attacker more to launch the attack, and for the victim to mitigate it. Cloudflare has seen very powerful attacks in the past over unencrypted HTTP, but this one was exceptional because of the resources it required at its scale.