On Thursday 12 September 2024 at 21:58 UTC, a HTTP GET flood targeted a tax authority portal customer in the UK. The attack peaked at 403.0 million requests per second and lasted 128 minutes. Traffic originated from 2592 autonomous systems in 86 countries, predominantly hijacked home routers.
| Vector | HTTP GET flood |
| Peak | 403.0 million requests per second |
| Duration | 128 min |
| Time to mitigation | 0.104 s |
| Attack traffic reaching origin | 0.061% |
| Legitimate traffic challenged | 0.66% |
Timeline
The attack was preceded by a competitor’s product launch. Request rates on the targeted routes exceeded their hourly baseline by a factor of 805 within 39 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
A brief increase in p99 latency of 198 ms during the first minute, then normal service.
Recommendations
- Keep origin IPs out of public DNS history.
- Enable log streaming to your SIEM for faster correlation.
- Enable authenticated origin pulls.
Solid runbook advice. The DNS-at-2am point hit home.
We had the exact false-positive issue with CGNAT carriers. The weighting change makes sense.
Could you share the dataset behind the percentages?
Our auditors asked for exactly this kind of incident evidence under DORA.