Individual skill

web-subdomain-takeover

Claim a dangling DNS record pointing to a deprovisioned service (subdomain takeover). Load after subdomain enum, on CNAMEs to cloud services, "NoSuchBucket"/"404 there isn't a GitHub Pages site here", or dangling A/CNAME. Signals: CNAME → S3/GitHub/Heroku/Azure/Fastly with a fingerprint error page.

skills/web/web-subdomain-takeover/SKILL.md

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Last checked: Nov 11, 2026

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Repository stars (not skill ratings): 27
Repository last updated: Oct 14, 2026
License: MIT

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# Subdomain takeover

## When it applies
A subdomain's DNS still points (CNAME/A) to a third-party service that no longer has the
resource provisioned, so you can register it and serve content on the victim's subdomain.

## Why it works
The org deleted the S3 bucket / GitHub Pages / Heroku app but left the DNS record. The provider
now serves that hostname to whoever claims the resource next — you. You control content on a
trusted subdomain (phishing, cookie theft on the parent domain, OAuth redirect_uri allowlist).

## Method
1. **Find candidates**: from subdomain enum, resolve CNAMEs (`dig CNAME sub.target.com`) and look
   for third-party targets with a "not claimed" fingerprint (`nuclei -t takeovers`, `subjack`).