On Wednesday 19 May 2021 at 17:23 UTC, a SYN flood targeted a online payments customer in the Middle East. The attack peaked at 126.4 Gbps and lasted 165 minutes. Traffic originated from 2286 autonomous systems in 60 countries, predominantly misconfigured open reflectors.
| Vector | SYN flood |
| Peak | 126.4 Gbps |
| Duration | 165 min |
| Time to mitigation | 0.116 s |
| Attack traffic reaching origin | 0.051% |
| Legitimate traffic challenged | 0.14% |
Timeline
The attack was preceded by an extortion email received two days earlier. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 14 points of presence.
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.
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Enable log streaming to your SIEM for faster correlation.
The billing model is what got our finance team on board, honestly.
We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.
Solid runbook advice. The DNS-at-2am point hit home.
Machine-readable ranges are at /ips.json and via the API.
How does the proof-of-work challenge behave on older Android devices? Any numbers below Android 10?
This matches what we see in iGaming around big matches.