Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add sanjaysaini1952/BugBounty-Arsenal --skill subdomain-takeovergit clone --depth 1 https://github.com/sanjaysaini1952/BugBounty-ArsenalWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/sanjaysaini1952/bugbounty-arsenal/subdomain-takeover)<a href="https://agentmods.dev/skills/sanjaysaini1952/bugbounty-arsenal/subdomain-takeover"><img src="https://agentmods.dev/badge/skills/sanjaysaini1952/bugbounty-arsenal/subdomain-takeover/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/sanjaysaini1952/bugbounty-arsenal/subdomain-takeover"><img src="https://agentmods.dev/badge/skills/sanjaysaini1952/bugbounty-arsenal/subdomain-takeover.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00000 | $0.00313 |
| Opus 5 | $0.00000 | $0.00156 |
| Sonnet 5 | $0.00000 | $0.00063 |
| Haiku 4.5 | $0.00000 | $0.00031 |
Grade A, and why
subdomain-takeover scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
Subdomain Takeover Hunting Skill — 5 Test Cases
Load when: subdomain takeover, dangling CNAME, abandoned subdomain.
197. Dangling CNAME detection (easy)
Resolve all subdomains. Check if CNAME points to unclaimed resource (S3, Heroku, GitHub Pages, Azure).
198. S3 bucket takeover (easy)
Check if CNAME points to *.s3.amazonaws.com and bucket doesn't exist. Attempt bucket creation.
199. Heroku/GitHub Pages takeover (medium)
Check if CNAME points to *.herokudns.com or *.github.io and app is deleted. Attempt claim.
200. Azure takeover (hard)
Check if CNAME points to *.azurewebsites.net and app is deleted. Attempt claim.
201. Expired domain takeover (hard)
Check if CNAME points to expired domain. Register domain and claim subdomain.
Takeover-able Services
| Service | Fingerprints |
|---|---|
| S3 | NoSuchBucket, NoSuchKey |
| Heroku | No such app |
| GitHub Pages | 404 Not Found (GitHub-styled) |
| Azure | Azure Web App - Error |
| Shopify | Sorry, this shop is currently unavailable |
| Fastly | Fastly error: unknown domain |
| Heroku DNS | Heroku DNS error: no such host |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 12d ago First seen · 32 lines · 0 tokens per session scan A 998f8f1939c5
subdomain-takeover is a skill published in the GitHub repository sanjaysaini1952/BugBounty-Arsenal (2 stars, last pushed 1mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 313 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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