Technical guide
Attack surface management: make external assets visible and owned
Attack surface management is the ongoing work of identifying exposed assets, understanding their ownership and risk, and reducing unnecessary exposure. Discovery is only the first step; an organization needs verification and remediation to turn it into risk reduction.
Create an asset inventory from multiple sources
Combine cloud accounts, DNS zones, certificate records, code repositories, deployment systems, and approved external discovery. No single source is complete. Record where each observation came from and when it was last confirmed.
Normalize hostnames and addresses, merge duplicates, and identify shared or third-party services. Verify that an asset belongs to your organization before scheduling active tests.
Prioritize exposure and ownership
Capture reachability, service type, software, authentication, data sensitivity, business purpose, and a responsible team. Use these details to distinguish a critical public service from an unneeded test asset or provider-managed endpoint.
Prioritize internet-facing systems with sensitive functions, known weaknesses, weak authentication, or unclear owners. Make ownership gaps visible; an unowned asset is difficult to patch or retire.
Move from discovery to reduction
Ask teams to confirm each asset, remove obsolete services, restrict access where public access is unnecessary, patch vulnerable software, and strengthen authentication and monitoring. Track actions with clear owners and deadlines.
Rescan or otherwise verify that a change reduced exposure. Preserve previous observations so teams can see whether an asset is new, recurring, or intentionally retained.
Keep the process safe
Set authorization boundaries before active validation. Respect cloud provider policies, partner contracts, rate limits, and sensitive systems. Separate passive discovery from active checks and require explicit approval for techniques that could affect availability.
RedCell documents recon and security-testing workflows that can help operators investigate authorized assets. Check current product behavior and configuration before including an agent in your attack surface process.