On Tuesday 17 August 2021 at 12:04 UTC, a memcached amplification targeted a retail banking customer in Iberia. The attack peaked at 293.3 Gbps and lasted 122 minutes. Traffic originated from 3020 autonomous systems in 75 countries, predominantly compromised cloud VMs.
| Vector | memcached amplification |
| Peak | 293.3 Gbps |
| Duration | 122 min |
| Time to mitigation | 0.428 s |
| Attack traffic reaching origin | 0.041% |
| Legitimate traffic challenged | 0.72% |
Timeline
The attack was preceded by a hacktivist channel announcing the target. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 23 points of presence.
What the customer saw
Checkout conversion was unchanged compared with the same hour of the previous week.
Recommendations
- Lower challenge thresholds on authentication endpoints during high-risk events.
- Review allow-listed partner ranges quarterly.
- Keep origin IPs out of public DNS history.
Interesting that most attacks are under ten minutes. Our experience is similar.