recon-asset-discovery

name	recon-asset-discovery
description	Subdomain enumeration, CT logs, DNS record catalog, WHOIS/RDAP, and passive reconnaissance for authorized external recon.
version	1.0.0
triggers	["subdomain enumeration","asset discovery","certificate transparency","crt.sh","WHOIS lookup","RDAP","DNS record catalog","passive recon","footprinting"]

Recon — Asset Discovery

Sub-skill of offensive-osint. Load osint-methodology for pipeline and triage context. Authorized targets only.

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BEHAVIORAL CONTRACT

When triggered: Subdomain enumeration, asset discovery, DNS records, CT logs, WHOIS/RDAP, or passive reconnaissance is needed.

Execute:

1. Run the passive subdomain-source stack (§1) in parallel across all listed sources. If crt.sh is down, follow the fallback chain.
2. Complement passive results with common-prefix candidates from the prefix wordlist (§2).
3. Run WHOIS/RDAP (§3) on the root domain. Extract registrant org/email for pivoting.
4. Catalog DNS records (§4) for every discovered domain/subdomain. Parse TXT records for SaaS tenancy inference using the verification token table.
5. Check autodiscover for M365 confirmation (§4).
6. Deduplicate all discovered assets by typed key. Tag each with confidence level per osint-methodology §2.

Output: Asset list with typed keys (subdomain, ip, domain) per osint-methodology §8 taxonomy.

Severity rules: DNS AXFR success = CRITICAL. Missing CAA = LOW.

Gating rules: Passive first. Active prefix sweep only when authorized. Brute-force (puredns) only with explicit operator approval.

Chain to: Feed discovered subdomains to web-surface for probing. Feed discovered emails to people-breach-intel for breach lookup. Feed discovered IPs to cloud-and-infra for infrastructure analysis.

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1. Subdomain-Source Stack (Passive)

Source	Tier	Notes
crt.sh	Free	Best single source; frequently 502s — see fallback chain
VirusTotal	Freemium	Domain → passive DNS history
AlienVault OTX	Free	Passive DNS + URL data
Shodan	Paid (low tier)	Subdomain enum via domain: filter
SecurityTrails	Paid	Passive DNS + asset discovery
RapidDNS	Free	Public passive DNS
Subfinder	Free	Aggregates 30+ free sources
Amass	Free	Thorough, slower
Recon-ng	Free	Modular framework

DNS AXFR opportunism:

dig @<ns-host> <target-domain> AXFR

Most NSs reject; those that don't = full zone disclosure (CRITICAL).

Brute-force tier: puredns against assetnote.io wordlists.

1.1 crt.sh Down? Fallback Chain

D="target.example"

# 1. Censys cert search (free 250 queries/month with key)
censys search "names: ${D}" --index-type certificates --fields names | jq -r '.names[]' | sort -u

# 2. Cert Spotter API (sslmate) — free w/ rate limits
curl -sk "https://api.certspotter.com/v1/issuances?domain=${D}&include_subdomains=true&expand=dns_names" | \
  jq -r '.[].dns_names[]' | sort -u

# 3. CertStream archive (Calidog)
curl -sk "https://crt.calidog.io/?q=${D}" | jq -r '.[].name_value' | sort -u

# 4. Subfinder bundled aggregator (30+ sources)
subfinder -d ${D} -all -recursive -silent

# 5. AlienVault OTX — free, no key
curl -sk "https://otx.alienvault.com/api/v1/indicators/domain/${D}/passive_dns" | \
  jq -r '.passive_dns[].hostname' | sort -u

# 6. ThreatMiner
curl -sk "https://api.threatminer.org/v2/domain.php?q=${D}&rt=5" | jq -r '.results[]'

# 7. URLScan
curl -sk "https://urlscan.io/api/v1/search/?q=domain:${D}" | \
  jq -r '.results[].page.domain' | sort -u

# 8. Anubis-DB (last resort)
curl -sk -A "Mozilla/5.0" "https://anubisdb.com/anubis/subdomains/${D}" | jq -r '.[]'

---

2. Common-Prefix Wordlist

119 prefixes. Passive enum misses 20-40% of high-value subdomains. Pair with active prefix probe when authorized (detectability: low -- single A-record query per host).

www mail webmail owa autodiscover ftp vpn sslvpn gateway api app portal
login sso idp iam identity accounts oauth auth adfs admin intranet hr
sap erp crm support help status grafana kibana docs wiki jira jenkins
gitlab dev test staging stg qa uat sandbox preprod preview careers jobs
eapps old legacy beta tender suppliers procurement
cdn static img images assets media files download upload search shop
store pay payment billing invoice ticket board chat meet video webinar
register signup sso-proxy proxy relay bounce mx smtp imap pop
ns1 ns2 ns3 dns ntp ldap radius vpn2 remote rdp citrix bastion jump
db mysql postgres redis mongo elastic kafka rabbit queue worker cron
monitor prometheus alertmanager vault consul log syslog splunk

2.1 Wordlist Sources

Source	URL	Notes
Assetnote Wordlists	https://wordlists.assetnote.io/	Best-curated; updated regularly
SecLists	https://github.com/danielmiessler/SecLists	Subdomains: Discovery/DNS/subdomains-top1million-110000.txt
jhaddix all.txt	https://gist.github.com/jhaddix/86a06c5dc309d08580a018c66354a056	Long-running curated
OneListForAll	https://github.com/six2dez/OneListForAll	Aggregated; very large
raft-large-words.txt	inside SecLists	Time-tested content wordlist
commonspeak2	https://github.com/assetnote/commonspeak2-wordlists	Generated from BigQuery
fuzzdb	https://github.com/fuzzdb-project/fuzzdb	Fuzzing payloads + wordlists

Size guidance:

Wordlist size	Speed class	Typical runtime	Use case
<10k entries	Fast	1–2 min	Quick validation, CI/CD gates
10k–100k entries	Standard	10–30 min	Standard engagement recon
100k–1M entries	Thorough	1–4 hours	Full-scope pentest
>1M entries	Exhaustive	Multi-day	Week-long engagements, red team ops

---

3. WHOIS / RDAP

whois target.example
curl -sk "https://rdap.org/domain/${D}" | jq .

What to extract: registrant org/email, registrar (pivot for related domains), created/updated dates (bulk registration patterns), nameservers (NS reuse pivot), status flags.

Historical WHOIS: Services like WhoisXMLAPI, SecurityTrails, and DomainTools archive past WHOIS snapshots. Historical records reveal previous registrant info hidden by current privacy services, ownership transfers, and infrastructure changes.

# SecurityTrails historical WHOIS (API key required)
curl -sk "https://api.securitytrails.com/v1/history/${D}/whois" -H "APIKEY: ${ST_KEY}" | jq '.result[] | {date: .first_seen, registrant: .registrant}'

Reverse WHOIS: Pivot from a known registrant name, email, or org to discover all domains they own:

• WhoisXMLAPI reverse WHOIS: search by registrant email or org name
• DomainTools reverse WHOIS: same capability, different corpus
• SecurityTrails: GET /v1/domain/search?filter[whois_email]={email}

This is a high-value pivot — a single registrant email can reveal dozens of related domains not discoverable through DNS or CT alone.

---

4. DNS Record Catalog

D="target.example"
for rtype in A AAAA MX TXT NS SOA CAA SRV CNAME PTR; do
  echo "=== ${rtype} ===" && dig +short "${D}" "${rtype}"
done

TXT verification tokens → SaaS tenancy inference (35 patterns):

TXT pattern	SaaS / service
google-site-verification=<token>	Google Workspace
MS=ms<digits>	Microsoft 365
adobe-idp-site-verification=<token>	Adobe
amazonses:<token>	AWS SES (alternate form)
_amazonses=<token>	AWS SES
apple-domain-verification=<token>	Apple
atlassian-domain-verification=<token>	Atlassian Cloud
calendly-site-verification=<token>	Calendly
cisco-ci-domain-verification=<token>	Cisco Webex
citrix-verification-code=<token>	Citrix
docker-verification=<token>	Docker
docusign=<token>	DocuSign
facebook-domain-verification=<token>	Facebook / Meta
github-verification=<token>	GitHub
gitlab-domain-verification=<token>	GitLab
hubspot-developer-verification=<token>	HubSpot (developer)
hubspot-domain-verification=<token>	HubSpot CRM
intercom-verification=<token>	Intercom
logmein-verification-code=<token>	LogMeIn / GoTo
miro-verification=<token>	Miro
onetrust-domain-verification=<token>	OneTrust
pinterest-site-verification=<token>	Pinterest
salesforce-domain-verification=<token>	Salesforce
slack-domain-verification=<token>	Slack Enterprise Grid
smartsheet-site-validation=<token>	Smartsheet
sophos-domain-verification=<token>	Sophos
status-page-domain-verification=<token>	Statuspage / Atlassian
stripe-verification=<token>	Stripe
teamviewer-sso-verification=<token>	TeamViewer
twilio-domain-verification=<token>	Twilio
workday-domain-verification=<token>	Workday (HR + Finance)
yandex-verification:<token>	Yandex
zoho-verification=<token>	Zoho
zoom_verify_<id>	Zoom
zscaler-verification-<id>-<date>-<random>	Zscaler (ZIA/ZPA/ZDX)

Each discovered tenancy is a separate attack surface (own credentials, own MFA posture).

Autodiscover-as-M365-confirmation:

dig +short A "autodiscover.target.example"

If IP lands in 40.96.0.0/13, 52.96.0.0/14, 13.107.0.0/16 → M365_CONFIRMED even when MX is wrapped by Mimecast/Proofpoint.

CAA records (cert issuance control):

dig +short CAA "${D}"

Absence = LOW (any CA can mis-issue). Presence + restrictive list = good posture.