DNS Penetration Testing Roadmap for Beginners

DNS is more than just translating domain names into IP addresses .
It’s a core part of any company’s security perimeter.
A weak DNS setup can expose:

• Hidden services
• Internal infrastructure
• Misconfigured subdomains
• Even full subdomain takeover attacks

This roadmap helps beginners and advanced learners understand how DNS attacks really work, starting from simple recon all the way to advanced exploitation - step by step.

Ethical & Legal Warning (Read First)​

DNS penetration testing must always be legal and authorized .
Never test any domain without written permission from the owner.
Always remember:

• ✔ Define the testing scope clearly
• ✔ Follow Rules of Engagement (RoE)
• ✔ Educational or authorized testing only

Unauthorized testing is illegal and unethical .

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Prerequisites Before DNS Pentesting​

Before jumping into DNS attacks, you should understand these basics

• DNS architecture
  • Authoritative servers
  • Recursive resolvers
• Common DNS record types
  • A, AAAA, MX, NS, CNAME, TXT, SOA, PTR, SRV
• Networking basics
  • UDP vs TCP
  • Port 53
• Comfortable using the Linux command line

Without these fundamentals, DNS pentesting will feel confusing and overwhelming.

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Essential DNS Pentesting Tools​

Using Kali Linux or a similar pentesting OS is highly recommended .
Most-used DNS security tools include:

• dig, nslookup, host
• dnsrecon, fierce
• amass, sublist3r, findomain
• gobuster (DNS mode)
• nmap
• dnscat2, iodine (DNS tunneling)

Example: Basic DNS Query Using dig dig example.com ANY
This command helps you quickly inspect available DNS records.

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Phase 1: Reconnaissance & Information Gathering​

Goal​

Understand the DNS footprint without making noise.

Passive Reconnaissance​

Passive recon uses public data and leaves no trace :

• Whois lookup to identify:
  • Domain owner
  • Name servers
• Google dorking to find indexed subdomains
• Certificate Transparency logs:
  • crt.sh
  • Censys

These sources often reveal hidden subdomains and services.

Active Reconnaissance​

Active recon talks directly to DNS servers:

• Identify authoritative name servers (NS records)
• Discover mail servers (MX records)
• Analyze SOA records:
  • Primary DNS server
  • Admin email

Example: dig example.com NS

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Phase 2: DNS Enumeration (Attack Surface Mapping)​

This is the most critical phase of DNS pentesting .

Zone Transfer (AXFR)​

If a DNS server is misconfigured, it may allow full zone transfers.

• Rare but very high impact
• Always test all authoritative name servers

Example: dig AXFR example.com @ns1.example.com

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Subdomain Enumeration​

If zone transfer fails, brute-force common subdomains:

• dev
• test
• admin
• vpn
• api
• mail

Tools like Amass and Gobuster are very effective.
Example: gobuster dns -d example.com -w subdomains.txt

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Reverse DNS (PTR) Scanning​

Reverse DNS looks up hostnames from IP ranges.

• Often reveals forgotten or internal systems
• Useful in large infrastructures

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DNSSEC NSEC Walking​

Misconfigured DNSSEC can allow attackers to enumerate the full zone.

• Similar impact to zone transfer
• Still seen in poorly configured environments

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Phase 3: Vulnerability Analysis & Exploitation​

Subdomain Takeover (High Impact)​

Occurs when a CNAME points to an unclaimed third-party service.
Common platforms:

• AWS
• GitHub Pages
• Heroku

Impact:

• Full control of a subdomain
• Phishing
• Malware hosting

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Dangling DNS Records​

A records pointing to IPs no longer owned by the company.
Attackers may:

• Reclaim those IPs
• Host malicious content

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DNS Server Software Vulnerabilities​

Identify DNS software and version:

• BIND
• Microsoft DNS

Then match it with known CVEs .
Sometimes version leaks appear inside TXT records.

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Cache Snooping & Poisoning​

Applies to recursive resolvers only.

• Cache snooping reveals browsing behavior
• Cache poisoning redirects users

Mostly mitigated today, but still relevant in legacy systems.

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Open DNS Resolvers​

Resolvers that answer queries from anyone.

• Abused in DNS amplification attacks
• Dangerous if publicly exposed

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Phase 4: Advanced & Post-Exploitation Concepts​

DNS Tunneling​

DNS traffic can be abused to bypass firewalls .
Used for:

• Data exfiltration
• Command & Control (C2)

Tools:

• dnscat2
• iodine

Internal Network DNS Attacks​

Inside corporate networks:

• LLMNR / NBT-NS spoofing (Responder)
• Active Directory DNS enumeration
• SRV records reveal:
  • Domain controllers
  • Internal services

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Phase 5: Reporting (The Most Important Skill)​

A pentester is judged by the report, not the tools .
Every finding should include:

1. Clear vulnerability description
2. Evidence (commands, logs, screenshots)
3. Business impact explanation
4. Clear remediation steps

Deep DNS knowledge makes you a stronger:

• Pentester
• Bug bounty hunter
• Blue team defender

DNS attacks are silent, powerful, and often ignored - which makes them extremely valuable to understand.