Threat Bulletin 1324: Slowloris against a developer platform platform in the UK

On Sunday 22 March 2026 at 09:37 UTC, a Slowloris targeted a developer platform customer in the UK. The attack peaked at 678.4 million requests per second and lasted 126 minutes. Traffic originated from 2527 autonomous systems in 25 countries, predominantly residential proxy networks.

Vector Slowloris
Peak 678.4 million requests per second
Duration 126 min
Time to mitigation 0.854 s
Attack traffic reaching origin 0.007%
Legitimate traffic challenged 0.79%

Timeline

The attack was preceded by an extortion email received two days earlier. Request rates on the targeted routes exceeded their hourly baseline by a factor of 492 within 7 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

  • Enable authenticated origin pulls.
  • Add a dedicated rate limit for the targeted route.
  • Keep origin IPs out of public DNS history.

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