CRITICAL SEVERITYCLOUDID: microsoft-azure
Microsoft Azure App Service Dangling DNS Takeover Fingerprint
An Azure App Service plan or slot was deleted while the DNS CNAME record remains active. Any Azure customer can create an App Service with the unallocated subdomain prefix and claim ownership.
CNAME Fingerprint Rule
*.azurewebsites.net / *.cloudapp.net
404 Not Found
Response Body Token
“404 Web Site not found”
When SubdomainWatch scanner receives HTTP responses matching this token on a dangling CNAME, it raises a critical alert immediately.
Remediation Guide & Mitigation
Action Required: Delete the dangling CNAME record from your authoritative DNS zone or re-bind the custom domain to an active Azure App Service plan.
Immediate Defensive Checklist:
- Audit authoritative DNS zone records for any CNAME records pointing to
*.azurewebsites.net / *.cloudapp.net. - Verify whether the corresponding target resource is still active in your cloud tenant.
- If the service was deprecated, delete the DNS record immediately to prevent hijackers from claiming the endpoint.
- Add automated continuous monitoring to alert before third parties can register matching resource names.
Monitor Microsoft Azure App Service In Real-Time
SubdomainWatch continuously monitors your DNS zones for orphaned Microsoft Azure App Service pointers, expired certificates, and dangling records 24/7.