Mitigation Guidelines
Verify cloud routing resources before deleting AWS buckets or SaaS instances. Regularly audit CNAME profiles to identify unresolved dangling nodes.
Security Threat Study
Dangling DNS Assets: Measuring the Prevalence of Subdomain Takeover Vectors
Published: 2026-06-04 (Updated: 2026-06-05)
Executive Summary
Subdomain takeover remains a high-severity threat. Attackers hijacking trust structures can execute phishing campaigns or steal session cookies scoped to root domains.
Key Telemetry Findings
2.4%
Dangling CNAME Rate
More than 2% of corporate DNS zones contain orphan third-party host points.
55.0%
S3 Target Vector Dominance
Amazon S3 remains the most common service vector for orphaned points.
30.0%
GitHub Pages Hijacking Risk
Unassigned GitHub Pages host CNAMEs allow immediate hijack.
// Subdomain Takeover Host Target Distribution
Data Metrics
Amazon S3
55%GitHub Pages
30%Heroku/Other SaaS
15%Study Methodology
Queried active CNAME pointers against known third-party host response headers (S3, GitHub Pages, Zendesk, etc.) to check for unassigned configurations.
Data Sources & Telemetry Scope
ReconShield Active DNS telemetry and external host state analysis.
How to Cite this Study
ReconShield Threat Research. "Subdomain Takeover & CNAME Hijacking Threat Report." June 2026. Available at https://reconshield.in/research/subdomain-takeover-report.