Threat Bulletin 1153: TLS handshake exhaustion against a online casino platform in the Middle East

On Monday 28 July 2025 at 12:25 UTC, a TLS handshake exhaustion targeted a online casino customer in the Middle East. The attack peaked at 399.1 million requests per second and lasted 64 minutes. Traffic originated from 2315 autonomous systems in 20 countries, predominantly hijacked home routers.

Vector TLS handshake exhaustion
Peak 399.1 million requests per second
Duration 64 min
Time to mitigation 0.700 s
Attack traffic reaching origin 0.046%
Legitimate traffic challenged 0.11%

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 426 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

The customer’s status page stayed green throughout; they learned about the attack from our notification.

Recommendations

  • Review allow-listed partner ranges quarterly.
  • Enable log streaming to your SIEM for faster correlation.
  • Enable authenticated origin pulls.

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