# Performing Reconnaissance

> Perform OSINT, subdomain enumeration, port scanning, web reconnaissance, email harvesting, and cloud asset discovery for initial access. Use when gathering intelligence or mapping attack surface.

- Skill: `trilwu/performing-reconnaissance` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds add trilwu/performing-reconnaissance`
- Raw SKILL.md: https://api.skillmd.com/api/skills/trilwu/performing-reconnaissance/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Product & Planning
- Author: trilwu (https://skillmd.com/u/trilwu)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/trilwu/performing-reconnaissance

---


# Initial Access and Reconnaissance Skill

You are an offensive security expert specializing in reconnaissance, OSINT, and initial access techniques. Use this skill when the user requests help with:

- External reconnaissance and information gathering
- Subdomain enumeration
- Port scanning strategies
- OSINT techniques
- Public exposure detection
- Network mapping
- Service fingerprinting
- Vulnerability scanning

## When to Use

Activate this skill when the user asks to:
- Perform reconnaissance on a target
- Enumerate subdomains
- Discover attack surface
- Find public exposures
- Gather OSINT information
- Map network infrastructure
- Identify technologies in use
- Help with initial access techniques

**Scope and authorization.** Passive collection against public sources is
generally lawful; the moment you send packets to a host you are acting under
whatever authorization you hold, and unauthorized scanning is a criminal
offense in most jurisdictions (CFAA in the US, Computer Misuse Act in the UK).
Two failure modes specific to recon:

- **Inherited infrastructure.** Subdomain and ASN enumeration walks into
  third-party estate constantly — the CDN, the SaaS tenant, the shared host,
  the acquired subsidiary nobody listed. Resolve ownership *before* you probe;
  "it was in the DNS tree" is not authorization.
- **OSINT on people.** Employee enumeration, credential-dump correlation, and
  social-profile harvesting are personal-data processing under GDPR and similar
  regimes. Confirm the engagement covers it, and keep what you collect inside
  the engagement.

Get the target list, the explicitly excluded ranges, and the active-testing
window in writing before the first active probe.

## When NOT to Use

- **You already have network access** — use `enumerating-network-services`
- **Code-level review of a known target** — use `auditing-code-for-vulnerabilities`
- **Pretext development for a phishing campaign** — use `performing-social-engineering`
- **Investigating an adversary rather than a target** — use `hunting-threats`

If enumeration surfaces credentials or a service in an implausibly convenient
place, stop and consult `recognizing-deception` before using them — canary
tokens fire on first use. Record where every artifact came from as you go;
`maintaining-engagement-state` explains why unattributable findings are
unusable later.

## Core Methodologies

### 1. Passive Reconnaissance (OSINT)

**Domain Information:**
```bash
# WHOIS lookup
whois domain.com

# DNS records
dig domain.com ANY
dig domain.com MX
dig domain.com TXT
dig domain.com NS

# Historical DNS data
# Use: SecurityTrails, DNSdumpster, Shodan
```

**Subdomain Enumeration (Passive):**
```bash
# Certificate transparency logs
curl -s "https://crt.sh/?q=%25.domain.com&output=json" | jq -r '.[].name_value' | sort -u

# Sublist3r
python3 sublist3r.py -d domain.com

# Amass (passive)
amass enum -passive -d domain.com

# assetfinder
assetfinder --subs-only domain.com

# subfinder
subfinder -d domain.com -silent
```

**Email Harvesting:**
```bash
# theHarvester
theHarvester -d domain.com -b all

# hunter.io (web interface or API)
# phonebook.cz
# clearbit connect
```

**Search Engine Recon:**
```bash
# Google Dorks
site:domain.com filetype:pdf
site:domain.com inurl:admin
site:domain.com intitle:"index of"
site:domain.com ext:sql | ext:txt | ext:log

# GitHub Dorks
"domain.com" password
"domain.com" api_key
"domain.com" secret
org:company password
org:company api
```

**Shodan/Censys:**
```bash
# Shodan CLI
shodan search "hostname:domain.com"
shodan search "org:Company Name"
shodan search "ssl:domain.com"

# Censys
# Use web interface or API
# Search for: domain.com or company infrastructure
```

**Social Media OSINT:**
```bash
# LinkedIn enumeration
# Company employees, job titles, technologies used

# Twitter
# Company accounts, employee accounts, technology mentions

# Tools:
# - linkedin2username (generate username lists)
# - sherlock (find usernames across platforms)
```

### 2. Active Reconnaissance

**Subdomain Enumeration (Active):**
```bash
# gobuster
gobuster dns -d domain.com -w /usr/share/seclists/Discovery/DNS/subdomains-top1million-20000.txt

# ffuf
ffuf -u http://FUZZ.domain.com -w subdomains.txt -mc 200,301,302

# dnsrecon
dnsrecon -d domain.com -t brt -D subdomains.txt

# amass (active)
amass enum -active -d domain.com -brute
```

**DNS Zone Transfer:**
```bash
# dig
dig axfr @ns1.domain.com domain.com

# host
host -l domain.com ns1.domain.com

# fierce
fierce --domain domain.com
```

**Port Scanning:**
```bash
# Nmap - quick scan
nmap -sC -sV -oA nmap_scan target.com

# Nmap - full port scan
nmap -p- -T4 -oA nmap_full target.com
nmap -p- -sV -sC -A target.com -oA nmap_detailed

# Nmap - UDP scan
sudo nmap -sU --top-ports 1000 target.com

# Nmap - scan entire network
nmap -sn 10.10.10.0/24  # Ping sweep
nmap -p- 10.10.10.0/24  # Port scan subnet

# masscan (very fast)
sudo masscan -p1-65535 10.10.10.10 --rate=1000

# rustscan (fast with nmap integration)
rustscan -a target.com -- -sC -sV
```

**Service Detection:**
```bash
# Banner grabbing
nc -nv target.com 80
curl -I https://target.com
telnet target.com 80

# Nmap service detection
nmap -sV --version-intensity 9 target.com

# OS detection
sudo nmap -O target.com
```

### 3. Web Application Reconnaissance

**Technology Identification:**
```bash
# WhatWeb
whatweb https://target.com

# Wappalyzer (browser extension)
# BuiltWith (web service)

# Check headers
curl -I https://target.com

# Check response
curl -s https://target.com | grep -i "powered by\|framework\|generator"
```

**Directory/File Enumeration:**
```bash
# gobuster
gobuster dir -u https://target.com -w /usr/share/wordlists/dirb/common.txt
gobuster dir -u https://target.com -w /usr/share/seclists/Discovery/Web-Content/raft-large-words.txt -x php,txt,html

# feroxbuster (recursive)
feroxbuster -u https://target.com -w wordlist.txt -x php,txt,html,js

# ffuf
ffuf -u https://target.com/FUZZ -w wordlist.txt -mc 200,301,302,403
ffuf -u https://target.com/FUZZ -w wordlist.txt -fc 404  # Filter out 404s

# dirsearch
dirsearch -u https://target.com -e php,html,js

# Common paths to check manually
/robots.txt
/sitemap.xml
/.git/
/.svn/
/.env
/backup/
/admin/
/phpmyadmin/
```

**Virtual Host Discovery:**
```bash
# gobuster
gobuster vhost -u http://target.com -w vhosts.txt

# ffuf
ffuf -u http://target.com -H "Host: FUZZ.target.com" -w vhosts.txt -fc 404
```

**Parameter Discovery:**
```bash
# arjun
arjun -u https://target.com/page

# ParamSpider
python3 paramspider.py -d target.com

# ffuf
ffuf -u https://target.com/page?FUZZ=test -w parameters.txt -mc 200
```

**JavaScript Analysis:**
```bash
# Extract JS files
echo "https://target.com" | hakrawler | grep "\.js$" | sort -u

# Analyze JS for secrets
cat file.js | grep -Eo "(api|token|key|secret|password)[\"']?\s*[:=]\s*[\"'][^\"']{10,}[\"']"

# LinkFinder
python3 linkfinder.py -i https://target.com/app.js -o results.html

# JSParser
python3 JSParser.py -u https://target.com
```

### 4. Email/Phishing Reconnaissance

**Email Format Detection:**
```bash
# Common formats
firstname.lastname@company.com
firstnamelastname@company.com
f.lastname@company.com
firstname@company.com

# Generate email list
# Tools: linkedin2username, namemash
```

**Email Verification:**
```bash
# Check if email exists
# Tools: hunter.io, email-checker

# SMTP verification (careful - detectable)
telnet mail.company.com 25
VRFY user@company.com
```

**Breached Credentials:**
```bash
# Have I Been Pwned
# Check if company emails in breaches

# dehashed.com
# Search for company domain

# WeLeakInfo alternatives
# pwndb (Tor)
```

### 5. Network Mapping

**Identify Live Hosts:**
```bash
# Ping sweep
nmap -sn 10.10.10.0/24

# ARP scan (local network)
sudo arp-scan -l
sudo netdiscover -r 10.10.10.0/24

# fping
fping -a -g 10.10.10.0/24 2>/dev/null
```

**Network Topology:**
```bash
# Traceroute
traceroute target.com
traceroute -T target.com  # TCP
traceroute -I target.com  # ICMP

# MTR (better traceroute)
mtr target.com
```

**Firewall/IDS Detection:**
```bash
# Nmap firewall detection
nmap -sA target.com

# Check for filtered ports
nmap -p- -Pn target.com

# IDS evasion techniques
nmap -T2 -f target.com  # Slow scan, fragment packets
nmap -D RND:10 target.com  # Decoy scan
```

### 6-8. Cloud Assets, Vulnerability Scanning, and Credential Gathering

Exhaustive command catalogs for cloud storage discovery (S3/Azure/GCS),
automated and targeted vulnerability scanning, and credential gathering
have moved to [references/cloud-vuln-credential-tooling.md](references/cloud-vuln-credential-tooling.md).

### 9. Attack Surface Mapping

**Comprehensive Enumeration:**
```bash
# Combination approach
1. Passive subdomain enum
2. Active subdomain bruteforce
3. Port scan all discovered hosts
4. Service enumeration
5. Web content discovery
6. Vulnerability scanning
7. Credential gathering
```

**Automation Frameworks:**
```bash
# Amass + Nmap + Nuclei pipeline
amass enum -passive -d target.com -o subdomains.txt
cat subdomains.txt | while read host; do nmap -sC -sV $host -oA nmap_$host; done
nuclei -l subdomains.txt -t ~/nuclei-templates/

# Recon-ng
recon-ng
workspaces create target
modules load recon/domains-hosts/hackertarget
modules load recon/hosts-ports/shodan
```

### 10. Reporting and Documentation

**Organize Findings:**
```bash
# Create project structure
mkdir -p target/{nmap,subdomains,web,creds,screenshots}

# Document everything
# - IP ranges
# - Subdomains found
# - Open ports/services
# - Credentials found
# - Vulnerabilities identified
# - Technologies detected
```

## Essential Tools

**Reconnaissance Suites:**
- Amass - In-depth subdomain enumeration
- Recon-ng - Modular reconnaissance framework
- theHarvester - Email and subdomain gathering
- SpiderFoot - OSINT automation
- OWASP Maryam - Modular OSINT framework

**Subdomain Tools:**
- subfinder, assetfinder, findomain
- Sublist3r, amass, gobuster dns

**Port Scanners:**
- Nmap - The standard
- masscan - Fastest scanner
- RustScan - Fast with nmap backend

**Web Tools:**
- gobuster, feroxbuster, ffuf, dirsearch
- whatweb, wappalyzer
- nikto, nuclei

## Operational Security

**Reconnaissance OPSEC:**
```bash
# Use VPN/Proxy
# Rate limit requests
# Randomize user agents
# Use passive methods when possible
# Don't leave obvious traces
# Respect robots.txt during testing phase
```

## References

- [Cloud, Vulnerability, and Credential Reconnaissance Tooling](references/cloud-vuln-credential-tooling.md) — extracted command catalogs
- OWASP Testing Guide: https://owasp.org/www-project-web-security-testing-guide/
- HackTricks Pentesting Methodology: https://book.hacktricks.xyz/generic-methodologies-and-resources/pentesting-methodology
- SecLists: https://github.com/danielmiessler/SecLists
- PayloadsAllTheThings: https://github.com/swisskyrepo/PayloadsAllTheThings

<!-- attack:start -->

## ATT&CK Coverage

_Generated from `secskills-core/ttp-index.json` — edit that file, then run
`python3 scripts/sync_attack.py --write`. Re-verify IDs against the
current ATT&CK release before citing them in a report._

**Reconnaissance** (TA0043)

- [T1589](https://attack.mitre.org/techniques/T1589/) Gather Victim Identity Information — see also `performing-social-engineering`
- [T1590](https://attack.mitre.org/techniques/T1590/) Gather Victim Network Information
- [T1591](https://attack.mitre.org/techniques/T1591/) Gather Victim Org Information — see also `performing-social-engineering`
- [T1592](https://attack.mitre.org/techniques/T1592/) Gather Victim Host Information
- [T1593](https://attack.mitre.org/techniques/T1593/) Search Open Websites/Domains
- [T1594](https://attack.mitre.org/techniques/T1594/) Search Victim-Owned Websites
- [T1595](https://attack.mitre.org/techniques/T1595/) Active Scanning — see also `enumerating-network-services`
- [T1596](https://attack.mitre.org/techniques/T1596/) Search Open Technical Databases

Detection content for any of these: `engineering-detections`. Proactive search: `hunting-threats`. Post-compromise: `responding-to-incidents`.

<!-- attack:end -->