On Wednesday 28 September 2022 at 07:57 UTC, a TLS handshake exhaustion targeted a electronics retail customer in the UK. The attack peaked at 917.2 million requests per second and lasted 68 minutes. Traffic originated from 1842 autonomous systems in 31 countries, predominantly misconfigured open reflectors.
| Vector | TLS handshake exhaustion |
| Peak | 917.2 million requests per second |
| Duration | 68 min |
| Time to mitigation | 0.528 s |
| Attack traffic reaching origin | 0.023% |
| Legitimate traffic challenged | 0.27% |
Timeline
The attack was preceded by a hacktivist channel announcing the target. Request rates on the targeted routes exceeded their hourly baseline by a factor of 357 within 11 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
The customer’s status page stayed green throughout; they learned about the attack from our notification.
Recommendations
- Review allow-listed partner ranges quarterly.
- Enable log streaming to your SIEM for faster correlation.
- Lower challenge thresholds on authentication endpoints during high-risk events.