Error Stack Proxy

Detection approach

Error Stack Trace Proxy Leak detected. The browser's native API error stacks (Object.create(apiFunction).toString() or instanceof checks) returned an Object-shadowed stack frame (containing 'at Object.toString' or similar) instead of the standard native 'at Function.toString'. Real browsers run native prototype functions in pristine frames, proving the environment is wrapped by active automation/stealth proxies.

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 running privacy-focused tools or ad-blockers that proxy native APIs to prevent fingerprinting.