Threat Bulletin 0231: TLS handshake exhaustion against a video streaming platform in North America

On Wednesday 12 January 2022 at 18:09 UTC, a TLS handshake exhaustion targeted a video streaming customer in North America. The attack peaked at 832.5 million requests per second and lasted 18 minutes. Traffic originated from 2101 autonomous systems in 87 countries, predominantly hijacked home routers.

Vector TLS handshake exhaustion
Peak 832.5 million requests per second
Duration 18 min
Time to mitigation 0.428 s
Attack traffic reaching origin 0.083%
Legitimate traffic challenged 0.05%

Timeline

The attack was preceded by a breaking political story. Request rates on the targeted routes exceeded their hourly baseline by a factor of 382 within 36 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

  • Add a dedicated rate limit for the targeted route.
  • Enable authenticated origin pulls.
  • Enable log streaming to your SIEM for faster correlation.

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