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Guide

External Attack Surface Checklist

A structured checklist for reviewing public-facing exposure before an external penetration test.

Inventory what is supposed to be public

  • Primary domains and subdomains
  • Cloud-hosted applications and APIs
  • VPN and remote access gateways
  • Email and identity endpoints
  • Vendor-hosted systems using your domain

Look for forgotten exposure

Development hosts, old DNS records, stale cloud services, temporary file shares, administrative interfaces, and acquired-company assets frequently survive longer than expected.

Review identity entry points

Understand where authentication is exposed, which systems allow password-only login, where legacy protocols exist, and how MFA is enforced.

Make ownership visible

Every public service should have a business owner, technical owner, expected purpose, and lifecycle decision.

Related next step

Use this resource as a starting point, then adapt it to the systems, business constraints, and threat model that actually apply to your organization.