hunting-subdomain-takeover-and-dangling-dns SKILL.md skillA
hunting-subdomain-takeover-and-dangling-dns from unboundcompute/security-agent-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add unboundcompute/security-agent-skills/hunting-subdomain-takeover-and-dangling-dns@git:20260823.e797ed0Pins git:20260823.e797ed0 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- unboundcompute/security-agent-skills
- Path
skills/hunting-subdomain-takeover-and-dangling-dns/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260823.e797ed0, committed Aug 23, 2026
- Size
- 9,611 bytes
- Repository stars
- 26
- License
- MIT
Hunt DNS records that point at infrastructure the organization no longer controls, so an attacker can claim the target and serve content under a trusted name. Covers a CNAME or ALIAS to a decommissioned platform host that the provider lets anyone re-register, a dangling NS delegation whose nameserver or zone no longer exists in the account, a record that outlives its resource because infrastructure-as-code or a teardown pipeline deletes the resource but not the record, and a wildcard or…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Hunting subdomain takeover and dangling DNS: who can claim the name you still point at A subdomain takeover is not a source-code bug, which is exactly why source-focused reviews miss it. It is a bug in DNS state: a record still resolves, but the thing it points at is gone, and the shared provider will hand that target to whoever asks next. When an attacker claims it, they serve content on your trusted origin, with a real certificate, inheriting parent-domain cookies, allowlist and content-policy trust, and OAuth redirect standing. You hunt it by inventorying the records, resolving each target, and asking one question per record: is the target still owned, and if not, can an attacker claim it. The discipline is separating a record that merely returns a 404 from one whose target is genuinely re-registrable, because only the second is a takeover. ## When to use - You have DNS zone files, or the DNS records declared in infrastructure-as-code, for a domain in scope. - A subdomain points at a platform host, storage bucket, content-delivery endpoint, or third-party service. - You want to know which records are dangling and, of those, which an attacker can actually claim. …
Read the whole file at its exact version.
How to install
mdr add unboundcompute/security-agent-skills/hunting-subdomain-takeover-and-dangling-dns@sha256:1a255fda0d07bf17The line at the top of this page pins the label git:20260823.e797ed0, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_s3bwmrvqbvcw4zog)
2 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 1 version of this file, committed on Aug 23, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (9611 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
unboundcompute/security-agent-skills · 26 stars · license MIT · pushed 2026-09-08 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_s3bwmrvqbvcw4zog GET https://markdownregistry.com/api/v1/resolve?ref=unboundcompute/security-agent-skills/hunting-subdomain-takeover-and-dangling-dns GET https://markdownregistry.com/api/v1/blob/1a255fda0d07bf174f3c24dcf86266ffc4c4e0f8011583dbb52becf7f19e748f
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.