Recon Skills is a pack of security-testing skills covering reconnaissance, web applications, APIs, authentication, vulnerability validation, cloud infrastructure, and reporting. Security professionals use it for authorized assessments of systems they own or have written permission to test. The catalogue entries are individual skills from the pack.
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 uphiago/recon-skills --skill subdomain-takeover-huntgit clone --depth 1 https://github.com/uphiago/recon-skillsWrote 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/uphiago/recon-skills/subdomain-takeover-hunt)<a href="https://agentmods.dev/skills/uphiago/recon-skills/subdomain-takeover-hunt"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/subdomain-takeover-hunt/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/uphiago/recon-skills/subdomain-takeover-hunt"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/subdomain-takeover-hunt.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Data Exfiltration · line 88 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
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 | $0.00023 | $0.01575 |
| Opus 5 | $0.00012 | $0.00788 |
| Sonnet 5 | $0.00005 | $0.00315 |
| Haiku 4.5 | $0.00002 | $0.00158 |
Grade A, and why
subdomain-takeover-hunt scanned grade A with 1 finding 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
compatibility: Requires curl, python3, subfinder, dnsx How it starts
The opening of the file, as written. The whole thing — 149 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Subdomain Takeover Detection
Detect subdomains pointing to unregistered or unclaimed third-party cloud services. When a CNAME record points to a service that no longer exists, an attacker can register that resource and serve arbitrary content under the target's subdomain — enabling phishing, cookie theft, and full origin impersonation.
When to Use
- Subdomain enumeration produces a large list — scan for lingering DNS records.
- Target uses cloud services with shared-namespace identifiers (Heroku, S3, Azure, Zendesk, Shopify).
- A subdomain returns NXDOMAIN, 404, or "no such app" error pages.
- The CNAME target is a service with user-registrable names.
Prerequisites
terminalwith curl, dnsx, subfinder.subzyorsubjackinstalled for automated detection.- List of alive subdomains from
subdomain-enumeration.
Quick Detection
# DNS resolution with CNAME extraction
dnsx -retry 3 -a -cname -resp -silent -l alive_subs.txt | tee dns_records.txt
# Automated takeover scan
subzy run --targets alive_subs.txt --hide_fails --vuln
Procedure
Phase 1 — Extract CNAME Records
# Get all CNAME records
cat alive_subs.txt | dnsx -silent -cname -resp-only > cname_targets.txt
# Filter to suspicious services
grep -iE "heroku|s3\.amazonaws|azure|zendesk|shopify|github\.io|bitbucket|surge\.sh|netlify|vercel|ghost\.io|readme|statuspage|pantheon|desk\.com|campaignmonitor|intercom|unbounce|wordpress\.com|cargo\.collective" \
cname_targets.txt > takeover_candidates.txt
Phase 2 — Automated Detection
# subzy — fast, shows vulnerable + fingerprint
subzy run --targets alive_subs.txt --hide_fails --vuln
# subjack — with custom fingerprints
subjack -w alive_subs.txt -t 100 -timeout 30 -o takeover_results.txt \
-ssl -c ~/subjack/fingerprints.json -v
# nuclei — takeover templates
nuclei -l alive_subs.txt \
-t nuclei-templates/takeovers/ \
-o nuclei_takeover_results.txt
Phase 3 — Manual Verification
# For each candidate, verify the service is claimable
CANDIDATE="api.target.com"
# Check what the CNAME points to
dig $CANDIDATE CNAME +short
# Check HTTP response
curl --max-time 30 --connect-timeout 10 -skI "https://$CANDIDATE" | head -10
# Key service-specific verification:
# Heroku: visit https://CANDIDATE — "no such app" = claimable
# S3: curl -s https://BUCKET_NAME.s3.amazonaws.com — 404 NoSuchBucket = claimable
# Zendesk: visit https://CANDIDATE — "account not found" = claimable
# GitHub Pages: dig CNAME returns user.github.io — 404 = claimable
# Azure: visit https://CANDIDATE — "tenant not found" = claimable
# Shopify: visit https://CANDIDATE — "Sorry, this shop is currently unavailable"
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 · 149 lines · 23 tokens per session scan A 4176ebd890e9
subdomain-takeover-hunt is a skill published in the GitHub repository uphiago/recon-skills (1,254 stars, last pushed 10d ago), licensed MIT. It adds 23 tokens to every session and 1,575 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other skills, from other repositories
auditing-aws-s3-bucket-permissions
Systematically audit AWS S3 bucket permissions to identify publicly accessible buckets, overly permissive ACLs, misconfigured bucket policies, and missing encryption settings using AWS CLI, S3audit, and Prowler to enforce least-privilege data access controls.
detecting-misconfigured-azure-storage
Detecting misconfigured Azure Storage accounts including publicly accessible blob containers, missing encryption settings, overly permissive SAS tokens, disabled logging, and network access violations using Azure CLI, PowerShell, and Microsoft Defender for Storage.
detecting-s3-data-exfiltration-attempts
Detecting data exfiltration attempts from AWS S3 buckets by analyzing CloudTrail S3 data events, VPC Flow Logs, GuardDuty findings, Amazon Macie alerts, and S3 access patterns to identify unauthorized bulk downloads and cross-account data transfers.
implementing-azure-defender-for-cloud
Implementing Microsoft Defender for Cloud to enable cloud security posture management, workload protection across VMs, containers, databases, and storage, configure security recommendations, and set up adaptive security controls with automated remediation.
detecting-azure-lateral-movement
Detect lateral movement in Azure AD/Entra ID environments using Microsoft Graph API audit logs, Azure Sentinel KQL hunting queries, and sign-in anomaly correlation to identify privilege escalation, token theft, and cross-tenant pivoting.
conducting-cloud-infrastructure-penetration-test
Perform a cloud infrastructure penetration test across AWS, Azure, and GCP to identify IAM misconfigurations, exposed storage buckets, insecure serverless functions, and cloud-native attack paths using Pacu, ScoutSuite, and Prowler.