← All bot detection signals2. Evasion, Debugger, & Anti-Stealth Traps

JS Engine Mismatch

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BotRefund combines browser, network, device, and behavior evidence to identify invalid traffic.

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Detection approach

JavaScript engine verification failed. The browser claims to be Chrome, but 'eval.toString().length' returned an anomalous length instead of 33, or Safari/Firefox returned a value other than 37. This indicates the underlying JS engine is spoofed.

How this helps detect bots

Collect this signal alongside session context, request metadata, and other independent indicators. A single anomaly is a lead, not a verdict; corroborating anomalies make automated traffic more likely.

Legitimate traffic to consider

Users on older browser builds or custom forks running modified JavaScript execution engines.

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