Subzy Tool

1. What is Subzy? Subzy is an automated subdomain takeover detection tool.

It is mainly used during: Reconnaissance phase of Bug Bounty Web Application Pentesting Asset security assessment In simple terms, Subzy helps identify dangling subdomains that may be vulnerable to subdomain takeover attacks.

2. What Problem Does Subzy Solve?

A subdomain takeover occurs when: A subdomain exists in DNS records But the service it points to (GitHub Pages, Heroku, AWS, Azure, etc.) is no longer active. An attacker can re-claim that service and control the subdomain

Subzy scans subdomains and detects such misconfigurations. 3. Technology Stack Language: Go (Golang) Type: CLI-based security tool Architecture: Signature & response-based detection Performance: Fast and lightweight (single binary)

4. How Subzy Works (Internally) Subzy follows these steps: Resolves subdomains from a given list Sends HTTP/HTTPS requests Matches responses against known service fingerprints Flags possible takeover vulnerabilities It uses predefined fingerprints for common third-party services.

5. Installation Using Go: 1. go install

2. github.com/LukaSikic/subzy@latest

Manual build: git clone https://github.com/LukaSikic/subzy cd subzy go build

6. Major Documentation Issue in Subzy ❗ Problem: subzy -h does NOT clearly explain the correct execution flow. The help menu lists commands But it does not clearly mention that Subzy must be started with run and --targets New users often try to scan domains directly and think the tool is broken.

This is a documentation and UX issue, not a tool bug.

7. Correct Way to Use Subzy (Important) Step 1: Collect subdomains subfinder -d example.com -o subs.txt

Step 2: Run Subzy properly subzy run --targets subs.txt This is the mandatory command structure. Without run --targets, Subzy will not function correctly. Optional flags: subzy run --targets subs.txt --hide_fails subzy run --targets subs.txt --verify_ssl

8. Understanding Subzy Output VULNERABLE → High chance of subdomain takeover NOT VULNERABLE → No takeover risk detected UNKNOWN / FAILED → Needs manual verification.

Warning: Never blindly trust automated results. 9. Limitations of Subzy Can produce false positives Does not support all cloud services Signature database may become outdated Help menu is misleading Requires manual confirmation Best used as a secondary verification tool, not the final authority.

10. Best Alternatives to Subzy

1. Nuclei (Recommended) Actively maintained Dedicated subdomain takeover templates Lower false positive rate Copy code Bash nuclei -l subs.txt -t takeovers/ Industry-standard tool. 2. Subjack Go-based Custom fingerprint support Old but still useful subjack -w subs.txt -t 100 -ssl

3. tko-subs Python-based Good for manual validation Setup is heavier

4. Manual Verification (Most Reliable) dig, nslookup Check HTTP response messages Cross-check with cloud provider behavior

11. Recommended Workflow Subdomain Enumeration ↓ Subzy (Quick Scan) ↓ Nuclei (Accurate Scan) ↓ Manual Verification This approach minimizes false positives and increases report accuracy.

12. Final Verdict Subzy is a useful reconnaissance tool, but: Poor documentation can confuse beginners Should not be blindly trusted Best used alongside Nuclei and manual checks When used correctly with: subzy run --targets it can significantly speed up the recon phase.