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Security7 min read

Man-in-the-Middle Attacks and Proxy Trust Models

How MITM attacks work through proxies, trust boundaries for HTTP CONNECT and SOCKS tunnels, and safe client configuration.

How MITM attacks work through proxies, trust boundaries for HTTP CONNECT and SOCKS tunnels, and safe client configuration.

What MITM means for proxies

A man-in-the-middle attacker intercepts traffic between client and server. With proxies, the proxy itself is a deliberate MITM — benign when trusted, dangerous when not. HTTPS inspection proxies actively decrypt traffic using a corporate CA.

CONNECT tunnels and blind relay

Standard HTTP CONNECT proxies relay encrypted TLS without decrypting. Your client validates the origin certificate directly. This is the safest model for third-party proxy pools.

Related: CONNECT method deep diveHTTPS and TLS tunneling.

Inspection proxies

Corporate gateways that decrypt HTTPS require installing a custom root CA on every client. Never apply this pattern to external scraping infrastructure.

Related: HTTPS inspection tradeoffs.

Defensive measures

  • Pin certificate validation on
  • Reject unknown CAs
  • Use providers you contract with
  • Alert on certificate changes
  • Isolate scrape workers from internal networks

Related: TLS certificate validation.

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