Threat Bulletin 1223: Slowloris against a sports betting platform in the Nordics

On Thursday 30 October 2025 at 23:41 UTC, a Slowloris targeted a sports betting customer in the Nordics. The attack peaked at 310.2 million requests per second and lasted 14 minutes. Traffic originated from 2104 autonomous systems in 36 countries, predominantly compromised cloud VMs.

Vector Slowloris
Peak 310.2 million requests per second
Duration 14 min
Time to mitigation 0.309 s
Attack traffic reaching origin 0.058%
Legitimate traffic challenged 0.70%

Timeline

The attack was preceded by no stated motive. Request rates on the targeted routes exceeded their hourly baseline by a factor of 533 within 38 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

Checkout conversion was unchanged compared with the same hour of the previous week.

Recommendations

  • Add a dedicated rate limit for the targeted route.
  • Enable authenticated origin pulls.
  • Lower challenge thresholds on authentication endpoints during high-risk events.

7 thoughts on “Threat Bulletin 1223: Slowloris against a sports betting platform in the Nordics”

  1. We moved from a scrubbing provider to always-on last year; time to mitigation went from minutes to basically nothing.

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