Web Reconnaissance: The First Step in Penetration Testing
Web reconnaissance is the foundation of any thorough security assessment. It involves collecting critical information about a target website or web application before diving into deeper analysis or exploitation. Think of it as digital detective work—it helps identify weaknesses and entry points before any attack is even launched.
Objectives of Web Reconnaissance
- Identifying Assets
- Discover web pages, subdomains, IPs, and technologies used.
- Gain a full picture of the target’s online presence.
- Discovering Hidden Information
- Locate exposed backup/config files or internal documents.
- These can unintentionally leak sensitive data.
- Analysing the Attack Surface
- Spot vulnerabilities by understanding tech stacks and misconfigurations.
- Gathering Intelligence
- Collect info that can aid in further exploitation (e.g., employee names, emails).
Both attackers and defenders use reconnaissance:
- Attackers to find weaknesses.
- Defenders to fix them first.
Types of Reconnaissance
Recon is typically divided into two categories:
Active Reconnaissance
This involves direct interaction with the target—more effective but riskier as it may trigger alerts.
| Technique | Description | Example Tools | Risk |
|---|---|---|---|
| Port Scanning | Finds open ports and running services | Nmap, Masscan | 🔺 High |
| Vulnerability Scanning | Probes for known flaws (e.g., XSS, SQLi) | Nessus, Nikto | 🔺 High |
| Network Mapping | Maps target’s network path | Traceroute, Nmap | 🔺 Medium–High |
| Banner Grabbing | Reads service banners for software/version | Netcat, curl | 🔸 Low |
| OS Fingerprinting | Detects the target’s operating system | Nmap (-O), Xprobe2 | 🔸 Low |
| Service Enumeration | Identifies exact versions of services | Nmap (-sV) | 🔸 Low |
| Web Spidering | Crawls website for structure, hidden files | Burp Suite Spider, OWASP ZAP | 🔸 Medium |
Pros: Detailed info
Cons: High chance of detection
Passive Reconnaissance
This technique gathers information without touching the target directly. It’s stealthy but may yield limited data.
| Technique | Description | Example Tools | Risk |
|---|---|---|---|
| Search Engine Queries | Google-fu to find data on target | Google, Shodan | Very Low |
| WHOIS Lookups | Reveals domain ownership info | WHOIS tools | Very Low |
| DNS Analysis | Identifies subdomains and mail servers | dig, dnsrecon | Very Low |
| Web Archive Analysis | Examines old versions of sites | Wayback Machine | Very Low |
| Social Media Analysis | OSINT via LinkedIn, Twitter, etc. | LinkedIn, Facebook | Very Low |
| Code Repositories | Checks GitHub for exposed code or secrets | GitHub, GitLab | Very Low |
Pros: Undetectable
Cons: Limited to publicly available data
Starting Point: WHOIS
The WHOIS protocol helps identify:
- Domain registrant details
- Contact info
- Name servers
- Expiry and creation dates
Understanding WHOIS gives you a good grasp of who owns the domain and how it’s structured, making it a crucial first step in reconnaissance.
Summary
- Web reconnaissance = digital footprint discovery
- It is vital for both attackers (to exploit) and defenders (to secure)
- Comes in two flavors: Active (direct, riskier) and Passive (indirect, stealthy)
- Tools like Nmap, WHOIS, Shodan, Burp Suite, and GitHub play a key role
- Mastering recon sets the stage for all further penetration testing phases