Threat Bulletin 0503: credential stuffing against a municipal services platform in Central Europe

On Wednesday 25 January 2023 at 15:43 UTC, a credential stuffing targeted a municipal services customer in Central Europe. The attack peaked at 704.4 million requests per second and lasted 89 minutes. Traffic originated from 2263 autonomous systems in 61 countries, predominantly a headless-browser farm.

Vector credential stuffing
Peak 704.4 million requests per second
Duration 89 min
Time to mitigation 0.425 s
Attack traffic reaching origin 0.040%
Legitimate traffic challenged 0.67%

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 470 within 26 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

  • Review allow-listed partner ranges quarterly.
  • Keep origin IPs out of public DNS history.
  • Enable log streaming to your SIEM for faster correlation.

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