CRITICAL SEVERITYHOSTINGID: github-pages
GitHub Pages Dangling DNS Takeover Fingerprint
A custom domain points via CNAME to a user.github.io host, but no GitHub repository currently claims this custom domain in its CNAME file. An attacker can create a public repo with a CNAME file claiming your domain.
CNAME Fingerprint Rule
*.github.io
404 Not Found
Response Body Token
“There isn't a GitHub Pages site here”
When SubdomainWatch scanner receives HTTP responses matching this token on a dangling CNAME, it raises a critical alert immediately.
Remediation Guide & Mitigation
Action Required: Remove the CNAME DNS record pointing to *.github.io, or configure a verified GitHub repository in your organization with this custom domain and enforce HTTPS.
Immediate Defensive Checklist:
- Audit authoritative DNS zone records for any CNAME records pointing to
*.github.io. - 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 GitHub Pages In Real-Time
SubdomainWatch continuously monitors your DNS zones for orphaned GitHub Pages pointers, expired certificates, and dangling records 24/7.
Related Cloud Takeover Signatures
CLOUDCRITICAL
AWS S3
*.s3.amazonaws.com / *.s3-website-*.amazonaws.com
HOSTINGCRITICAL
Heroku App
*.herokudns.com / *.herokuapp.com
CLOUDCRITICAL
Microsoft Azure App Service
*.azurewebsites.net / *.cloudapp.net
CLOUDCRITICAL
AWS CloudFront
*.cloudfront.net
CLOUDCRITICAL
AWS Elastic Beanstalk
*.elasticbeanstalk.com
DNSHIGH
Fastly CDN
*.fastly.net