CyberCheatsheets

Assetfinder Cheat Sheet

Find domains and subdomains related to a given domain using passive sources (Tom Hudson).

Reconnaissance & OSINTosintpassivesubdomainUpdated 2026-06-02

Overview

Assetfinder returns hostnames related to a target domain by querying passive sources (crt.sh, various APIs when configured). Lightweight and ideal for chaining in shell one-liners with other enum tools.

Authorized testing only. Queries passive intelligence sources; ensure target domain is in scope for the engagement or bug bounty program.

Install

go install github.com/tomnomnom/assetfinder@latest
assetfinder --help

Essential commands

Subdomains for domain

assetfinder target.example.com

Include parent domain in output

assetfinder --subs-only target.example.com

Multiple domains

cat domains.txt | assetfinder --subs-only

Common workflows

Merge with subfinder / amass —

{
subfinder -d target.example.com -silent
assetfinder --subs-only target.example.com
amass enum -passive -d target.example.com
} | sort -u | httpx -silent -o live.txt

Scope filter (manual) —

assetfinder target.example.com | grep '\.target\.example\.com$' | tee subs.txt

Flags reference

--subs-only

Subdomains only (exclude parent)

(stdin)

Pass domains one per line

Tips

  • Set API-related env vars if using extended sources (see project README).
  • Very fast—use as first pass before heavier amass enum.
  • Always dedupe and verify ownership before scanning (httpx, nuclei).
  • Does not replace active DNS brute force for hidden names.

References

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