Threat Bulletin 0514: login endpoint flood against a B2B SaaS platform in the Nordics

On Friday 10 February 2023 at 19:47 UTC, a login endpoint flood targeted a B2B SaaS customer in the Nordics. The attack peaked at 88.1 million requests per second and lasted 67 minutes. Traffic originated from 2586 autonomous systems in 39 countries, predominantly residential proxy networks.

Vector login endpoint flood
Peak 88.1 million requests per second
Duration 67 min
Time to mitigation 0.463 s
Attack traffic reaching origin 0.004%
Legitimate traffic challenged 0.25%

Timeline

The attack was preceded by a ransom note demanding payment in Monero. Request rates on the targeted routes exceeded their hourly baseline by a factor of 466 within 34 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

No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.

Recommendations

  • Add a dedicated rate limit for the targeted route.
  • Keep origin IPs out of public DNS history.
  • Enable log streaming to your SIEM for faster correlation.

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