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find-hidden-subdomains

90 / 100 · Low risk

Fine to try. Some of what it can do is expected: a security skill usually runs scanners and checks websites.

By UseOSINT/Skills (GitHub) · security · 61 stars · scanned at commit 06243a5

Enumerate an organisation's subdomains and sibling domains from Certificate Transparency logs and passive DNS, without sending traffic to the target. Covers crt.sh and CT log queries, certificate SAN fields, subfinder and amass, and newly issued TLS certificates. Use when looking for staging, dev, admin or VPN hosts, mapping the full hostname footprint of a domain, or spotting infrastructure a company forgot it had. Applies to attack-surface mapping, vendor and supply-chain security review, bra…

Works with any agent that supports SKILL.md skills.

What this skill can do

Install

Paste this into your terminal. It downloads exactly the version we scanned, not whatever is newest.

if [ -e ~/.agents/skills/'find-hidden-subdomains' ] || [ -L ~/.agents/skills/'find-hidden-subdomains' ]; then echo 'A skill folder named find-hidden-subdomains already exists — not replacing it' >&2; false; else d=$(mktemp -d) && git clone --quiet --filter=blob:none --no-checkout 'https://github.com/UseOSINT/Skills' "$d" && git -C "$d" checkout --quiet '06243a5620b0c9c97502edd4ee9e31995a3bdccd' -- 'skills/find-hidden-subdomains' && mkdir -p ~/.agents/skills && cp -R "$d"/'skills/find-hidden-subdomains' ~/.agents/skills/'find-hidden-subdomains' && rm -rf "$d"; fi

Codex reads ~/.agents/skills directly. For Claude Code, Cursor, Copilot, Gemini CLI, Antigravity or OpenCode, also link it. For Claude Code: ln -s ~/.agents/skills/'find-hidden-subdomains' ~/.claude/skills/'find-hidden-subdomains' (other agents: ~/.cursor/skills, ~/.copilot/skills, ~/.gemini/skills, ~/.gemini/config/skills, ~/.config/opencode/skills). Or install through the finder skill, which does both.

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