MediumVDP30 min
Subdomain Takeover via Dangling CNAME
Portal del gobierno ficticio con un subdominio legacy que apunta a un repositorio de GitHub Pages inexistente. El atacante debe descubrir el subdominio, identificar el CNAME dangling, reclamar el repositorio y tomar control del subdominio
263 views13 completedUpdated Aug 2026
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Objectives
1
Reconocimiento → explorar la web del gobierno2
Inspeccionar código fuente → descubrir subdominio en footer/robots.txt3
Añadir portal.gobierno.gob.local al /etc/hosts4
Visitar subdominio → GitHub Pages 4045
Identificar el CNAME target (hash.github.io)6
Crear el repositorio en GitHub (o usar /api/claim para simulación)7
Subir contenido → subdominio tomado8
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Subdomain Takeover via Dangling CNAME
Business Logic
Aug 2026
solved_by@gorkaMember since Mar 2026
bblabs.es// real bug bounty practice
Community writeups
Setup
Añadir al /etc/hosts:
127.0.0.1 gobierno.gob.local
127.0.0.1 portal.gobierno.gob.local
Desplegar:
./autodeploy.sh
# o: docker compose up --build
Acceder: http://gobierno.gob.local:1000