external-enumeration

external-enumeration is a skill for Claude Code, Codex from forefy/.context. It costs 37 tokens per session (3,409 once invoked), scanned A, original, MIT.

A passive investigation of a company’s internet-facing domains and subdomains. It maps domain ownership, DNS records, hosting technology, and related security observations without actively attacking the systems.

In plain words
What is it for?
Use it to map domains, subdomains, DNS ownership, technology stacks, and content-delivery networks, then document the external attack surface.
Why use it?
It shows what infrastructure may be publicly connected to a company while limiting the investigation to information already available from outside.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/forefy/.context/external-enumeration
Any agent
npx skills add forefy/.context --skill external-enumeration
Clone the repo
git clone --depth 1 https://github.com/forefy/.context

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for external-enumeration

README.md
[![agentmods](https://agentmods.dev/badge/skills/forefy/.context/external-enumeration.svg)](https://agentmods.dev/skills/forefy/.context/external-enumeration)
Your own site
<a href="https://agentmods.dev/skills/forefy/.context/external-enumeration"><img src="https://agentmods.dev/badge/skills/forefy/.context/external-enumeration.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,409 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00037 $0.03409
Opus 5 $0.00018 $0.01705
Sonnet 5 $0.00007 $0.00682
Haiku 4.5 $0.00004 $0.00341

Measured 5d ago against content hash a3c4624fb608, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

external-enumeration scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -s "https://crt.sh/?q=%.example.com&output=json" \
skills/hunter-utils/external-enumeration/SKILL.md · 370 lines

How it starts

The opening of the file, as written. The whole thing — 370 lines — stays where its author put it; the contents beside it link to each section on GitHub.

External Enumeration Skill

You are performing passive external reconnaissance on a target company's domain infrastructure. Goal: produce a comprehensive, structured map of all domains, subdomains, technology stack, and notable security observations - using only passive/OSINT techniques (no active exploitation).


Phase 0 - Scope Clarification

Ask the user for:

  1. Primary domain(s) to enumerate (e.g. example.com)
  2. Known subsidiaries or related companies (acquisitions, brand names, sister domains)
  3. Output format - markdown report to a file path?
  4. Depth - quick pass (passive DNS only) or deep pass (stealth browser + port scan)?

Phase 1 - Domain Ownership & Attribution

Before enumerating subdomains, confirm what domains are actually owned by the target.

1.1 WHOIS Check

whois <domain> | grep -iE 'registrar|creation|name server|registrant'

Note: Most domains use privacy protection (e.g. GoDaddy DomainsbyProxy) - registrant names will be hidden. Do NOT rely on registrant names for attribution.

1.2 Nameserver Correlation (Primary Attribution Method)

for d in domain1.com domain2.io domain3.net; do
  echo -n "$d: "; dig NS $d +short | sort | tr '\n' ' '; echo
done

Identical NS pairs = same DNS account = same owner. This is the strongest passive attribution proof even when WHOIS is privacy-protected.

1.3 MX + TXT Record Cross-Reference

dig MX <domain> +short
dig TXT <domain> +short
  • Shared *.mail.protection.outlook.com MX = same Microsoft 365 tenant
  • TXT records reveal: Azure site verifications, Google Workspace, Atlassian, SendGrid
  • Azure TXT format: MS=ms... or azurewebsites.net subdomain references → same Azure tenant

1.4 Similar-Name Domain Trap

Note: Always verify similar-sounding domains (e.g. target.net, target.co) are actually owned by the target - different registrar or NS pair = likely unrelated squatter. Never assume.


Phase 2 - Multi-Source Subdomain Enumeration

Read the full file on GitHub · 370 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago First seen · 370 lines · 37 tokens per session scan A a3c4624fb608

Subscribe to this mod's changes

external-enumeration is a skill published in the GitHub repository forefy/.context (144 stars, last pushed yesterday), licensed MIT. It adds 37 tokens to every session and 3,409 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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