Active Probing & Surface
critical Severity
Free Check

Subdomain Takeover Vulnerability (Dangling CNAMEs)

Detects dangling CNAME records pointing to decommissioned third-party cloud services (AWS S3, GitHub Pages, Heroku).

Test Your Website for Subdomain Takeover Vulnerability (Dangling CNAMEs)

Run this check along with 90+ automated tests across your domain.

Why It Matters

An attacker can claim the abandoned bucket or service name and host malicious phishing content directly on your trusted domain.

How We Check This

We resolve subdomains, check CNAME targets against known vulnerable fingerprinted providers, and probe for "NoSuchBucket" or "Unregistered Domain" signatures.

How to Fix & Implement

Copy-paste configuration blocks tailored for your web server or edge proxy.

nginx snippet
# Delete orphaned CNAME DNS records immediately from your DNS zone

Frequently Asked Questions

What services are most vulnerable to subdomain takeover?

AWS S3, GitHub Pages, Heroku, Vercel, Netlify, Azure Traffic Manager, and Zendesk.