subdomain-enumeration

1# Subdomain Enumeration Skill
2 
3Comprehensive subdomain discovery using certificate transparency logs (crt.sh), DNS brute force, and passive sources. The first step in any recon pipeline — you can't attack what you don't know exists. Subdomain enumeration consistently reveals staging environments, internal admin panels, API gateways, and forgotten WordPress installs that are softer targets than the production site.
4 
5## When to Use
6 
7- Starting recon on any target domain.
8- Production site is well-secured — find softer entry points.
9- After `skill_view(name='wp-mass-recon')` — enumerate subdomains for each WordPress target.
10- Building a complete asset inventory for a target organization.
11 
12## Prerequisites
13 
14- `curl`, `httpx`, `dig`, `jq`, `dnsx`, and `subfinder`.
15- A DNS brute-force wordlist, supplied by the operator.
16- Approval to disclose the domain to third-party passive sources such as crt.sh, crt.name, and subfinder providers.
17 
18## How to Run
19 
20```bash
21DOMAIN="${1:-example.com}"
22OUTPUT_ROOT="${OUTPUT_DIR:-./output}"
23OUTDIR="$OUTPUT_ROOT/subdomains/$DOMAIN"
24 
25if [[ ! "$DOMAIN" =~ ^[A-Za-z0-9.-]+$ ]]; then
26  echo "Invalid domain: $DOMAIN" >&2
27  exit 2
28fi
29 
30mkdir -p "$OUTDIR"
31 
32# Passive: crt.sh (retry: it frequently returns 502 while its database refreshes)
33for attempt in 1 2 3; do
34  curl -fsS --max-time 30 --connect-timeout 10 \
35    "https://crt.sh/?q=%25.$DOMAIN&output=json" -o "$OUTDIR/crtsh_raw.json" && break
36  sleep 15
37done
38…