Last week, Cloudflare automatically detected and mitigated a 26 million request per second DDoS attack — the largest HTTPS DDoS attack on record.
The attack targeted a customer website using Cloudflare’s Free plan. Similar to the previous 15M rps attack, this attack also originated mostly from Cloud Service Providers as opposed to Residential Internet Service Providers, indicating the use of hijacked virtual machines and powerful servers to generate the attack — as opposed to much weaker Internet of Things (IoT) devices.
Over the past year, we’ve witnessed one record-breaking attack after the other. Back in August 2021, we disclosed a 17.2M rps HTTP DDoS attack, and more recently in April, a 15M rps HTTPS DDoS attack. All were automatically detected and mitigated by our HTTP DDoS Managed Ruleset which is powered by our autonomous edge DDoS protection system.
The 26M rps DDoS attack originated from a small but powerful botnet of 5,067 devices. On average, each node generated approximately 5,200 rps at peak. To contrast the size of this botnet, we’ve been tracking another much larger but less powerful botnet of over 730,000 devices. The latter, larger botnet wasn’t able to generate more than one million requests per second, i.e. roughly 1.3 requests per second on average per device. Putting it plainly, this botnet was, on average, 4,000 times stronger due to its use of virtual machines and servers.
Also, worth noting that this attack was over HTTPS. HTTPS DDoS attacks are more expensive in terms of required computational resources because of the higher cost of establishing a secure TLS encrypted connection. Therefore, it costs the attacker more to launch the attack, and for the victim to mitigate it. We’ve seen very large attacks in the past over (unencrypted) HTTP, but this attack stands out because of the resources it required at its scale.
Within less than 30 seconds, this botnet generated more than 212 million HTTPS requests from over 1,500 networks in 121 countries. The top countries were Indonesia, the United States, Brazil and Russia. About 3% of the attack came through Tor nodes.
The top source networks were the French-based OVH (Autonomous System Number 16276), the Indonesian Telkomnet (ASN 7713), the US-based iboss (ASN 137922) and the Libyan Ajeel (ASN 37284).