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).
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.