Threat Bulletin 0592: search endpoint flood against a tax authority portal platform in Latin America

On Wednesday 31 May 2023 at 11:12 UTC, a search endpoint flood targeted a tax authority portal customer in Latin America. The attack peaked at 534.9 million requests per second and lasted 6 minutes. Traffic originated from 2316 autonomous systems in 20 countries, predominantly a Mirai-derived IoT botnet.

Vector search endpoint flood
Peak 534.9 million requests per second
Duration 6 min
Time to mitigation 0.816 s
Attack traffic reaching origin 0.032%
Legitimate traffic challenged 0.24%

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 285 within 8 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 37 ms during the first minute, then normal service.

Recommendations

  • Keep origin IPs out of public DNS history.
  • Enable authenticated origin pulls.
  • Lower challenge thresholds on authentication endpoints during high-risk events.

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