In the third quarter of 2023, Cloudflare faced an unprecedented surge in hyper-volumetric HTTP DDoS (distributed denial of service) attacks, signaling a new chapter in the threat landscape. These attacks overwhelmed targeted servers with large volumes of bogus requests, making websites and online services temporarily unavailable to legitimate users.
Cloudflare’s report disclosed that they mitigated thousands of these attacks during Q3, with over 89 exceeding 100 million requests per second (rps), and the largest peaking at a staggering 201 million rps, three times larger than any previous record. These attacks were made possible by exploiting a newly disclosed technique called ‘HTTP/2 Rapid Reset,’ which threat actors have been leveraging since August 2023.
What sets these attacks apart is the use of VM-based botnets, typically consisting of 5-20 thousand nodes, instead of millions of weak IoT devices. This allows for a more significant impact per node. Cloudflare reported a 65% increase in the aggregated volume of HTTP DDoS attack traffic during the last quarter, along with a 14% increase in L3/L4 DDoS attacks. The primary targets during this period were gaming and gambling entities, followed by IT and internet services, cryptocurrency, software, and telecommunications. On the other hand, application-layer DDoS attacks mainly targeted mining firms, non-profit organizations, pharmaceuticals, and the U.S. Federal government.
Notably, Cloudflare observed emerging trends in lesser-known attack vectors, indicating the evolution of new attack strategies. These trends include a 456% quarterly increase in observed mDNS (multicast DNS) attacks, a 387% increase in CoAP (Constrained Application Protocol) attacks, and a 303% increase in ESP (Encapsulating Security Payload) DDoS attacks during the quarter.
Furthermore, ransom DDoS attacks have seen a negative trend, declining for the second successive quarter. As DDoS attacks continually evolve, a comprehensive, multi-layered defense strategy is crucial to enhance DDoS resilience, especially as new techniques emerge.
