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Cloudflare WAF rule that blocked a 1.2M-req/s scrape attempt

Clustrix Admin · May 7, 2026 · 5 min read

Last quarter we mitigated a content-scrape attack against a media client. The pattern was distinctive: rotating IPs, no JS execution, unusual UA fingerprints.

The rule

We matched on the combination of: low cf_threat_score, missing accept-language, missing referer, and request method GET on /api paths. Action: block.

Within 90 seconds traffic stabilized at baseline.

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That's the level of attention we put into every client's infrastructure.