On Sunday 23 April 2023 at 11:38 UTC, a TLS handshake exhaustion targeted a gaming community customer in the UK. The attack peaked at 476.0 million requests per second and lasted 146 minutes. Traffic originated from 3867 autonomous systems in 79 countries, predominantly a Mirai-derived IoT botnet.
| Vector | TLS handshake exhaustion |
| Peak | 476.0 million requests per second |
| Duration | 146 min |
| Time to mitigation | 0.656 s |
| Attack traffic reaching origin | 0.078% |
| Legitimate traffic challenged | 0.20% |
Timeline
The attack was preceded by an extortion email received two days earlier. Request rates on the targeted routes exceeded their hourly baseline by a factor of 109 within 37 seconds. The risk score of participating clients crossed the challenge threshold automatically and proof-of-work difficulty rose with origin load.
What the customer saw
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Add a dedicated rate limit for the targeted route.
- Enable authenticated origin pulls.
- Enable log streaming to your SIEM for faster correlation.