curiouslearnerdev/online_tools-ai/subdomain-enum

subdomain-enum

Subdomain and DNS reconnaissance workflow for HexStrike AI. Use this skill when a user wants to enumerate subdomains, discover DNS records, find email addresses, or build a full attack surface map for a domain.

Workflow

1. Passive subdomain discovery (subfinder)

Start passive — no direct DNS queries to the target, low noise:

run_tool(tool="subfinder", domain="<target.com>", silent=true, all_sources=true)

2. Active subdomain enumeration (amass)

Follow up with amass for active DNS brute-force and graph-based enumeration:

# Passive mode (intelligence gathering only)
run_tool(tool="amass", domain="<target.com>", mode="enum",
         additional_args="-passive")
 
# Active mode (DNS resolution, zone transfers)
run_tool(tool="amass", domain="<target.com>", mode="enum",
         additional_args="-active -brute")

3. DNS zone transfer and record enumeration (dnsenum)

Attempt zone transfers and enumerate MX, NS, A, CNAME records:

run_tool(tool="dnsenum", domain="<target.com>")

4. DNS reconnaissance (fierce)

Fierce does brute-force subdomain discovery and identifies nearby IP ranges:

run_tool(tool="fierce", domain="<target.com>")

5. Email, host, and URL harvesting (theharvester)

Collect emails, hosts, and IPs from public sources (Google, Bing, LinkedIn, etc.):

run_tool(tool="theharvester", domain="<target.com>")

6. Historical URL discovery (gau + waybackurls)

Pull archived URLs to find forgotten endpoints, old parameters, and legacy paths:

run_tool(tool="gau", domain="<target.com>")
run_tool(tool="waybackurls", domain="<target.com>")

Feed the results into web-vuln skill tools (nuclei, sqlmap) for vulnerability testing.

7. WHOIS lookup

Gather registration info, nameservers, and ASN data:

run_tool(tool="whois", target="<target.com>")

8. HTTP probe discovered subdomains (httpx)

After collecting subdomains, probe which ones are live:

run_tool(tool="httpx", target="<subdomains_file_or_list>",
         probe=true, title=true, status_code=true, tech_detect=true)

Attack surface map — full pipeline

subfinder → amass → dnsenum/fierce → theharvester
                       ↓
                    httpx probe
                       ↓
              web-recon + web-vuln skills

Tips

• Run subfinder and amass in parallel — they use different data sources.
• Always probe discovered subdomains with httpx before scanning — many will be dead.
• Historical URLs from gau/waybackurls often expose parameters that are still live but not linked from the main site.
• Zone transfers (dnsenum) are rare but high-value — always attempt them.

HexStrike Tool Reference