Starting on Aug 25, 2023, we started to notice some unusually big HTTP attacks hitting many of our customers. These attacks were detected and mitigated by our automated DDoS system. It was not long however, before they started to reach record breaking sizes — and eventually peaked just above 201 million requests per second. This was nearly 3x bigger than our previous biggest attack on record.
Earlier today, Cloudflare, along with Google and Amazon AWS, disclosed the existence of a novel zero-day vulnerability dubbed the “HTTP/2 Rapid Reset” attack. This attack exploits a weakness in the HTTP/2 protocol to generate enormous, hyper-volumetric Distributed Denial of Service (DDoS) attacks.
Modern cloud applications are made up of thousands of distributed services and resources that support an equally large volume of concurrent requests. This level of scale makes it more challenging for engineers to identify system failures before they lead to costly outages. System failures are often difficult to predict in cloud environments, and security threats add another layer of complexity.