The Modern Target: An Exploding Attack Surface

​The core lesson was that a bug bounty target is a full digital infrastructure, not just a website. To be a professional hunter, you must understand all target areas:

​Web Applications:

Still the most targeted asset, including testing for OWASP Top 10, SSRF, RCE, and Auth flaws.

​API:

Tested using Postman or Burp for flaws like IDOR, Mass Assignment, broken authentication, and information leakage.

​Mobile (Android/iOS):

Requires specialized knowledge. For Android, we analyze APKs using MobSF for permissions or hardcoded keys, and use Genymotion for dynamic testing. iOS testing often involves jailbroken devices to check insecure transport and logging.

​Cloud:

Hunting AWS/GCP misconfigurations like S3 bucket takeover, exposed EC2 keys, or IAM policy abuse.

​Network:

Identifying open ports, weak services, default credentials, and CVEs using tools like Nmap and Nessus.

​IoT & OT Devices:

Includes routers and smart devices, looking for open ports, default creds, and firmware bugs, though OT Devices are rare in bounty programs.

Finding Hidden Doors with Bruteforce and Fuzzing

​The key to discovering unlinked administrative panels, private API endpoints, or hidden backup folders is Directory Bruteforcing. Directory Bruteforcing is the method we use to systematically guess these paths.

The Tool Stack for Speed and Efficiency

FFUF (Fast Fuzzer):

This was the star. Written in Go, FFUF is incredibly flexible, allowing us to specify exactly where to inject our wordlist using the keyword FUZZ. It's not just for directories; we learned to use it for parameter and header fuzzing, too!

Gobuster:

Another reliable, Go-based tool used for high-speed directory and DNS enumeration.

Dirsearch:

A Python tool specifically for brute-forcing web directories and files.

The valuable takeaway:

Don't just look for a successful 200 OK response. Finding a 403 Forbidden response is often gold because it confirms the resource exists, paving the way for advanced 403 Bypass techniques!

Finding Forgotten Digital Crumbs and Sensitive Data

Beyond brute-forcing, we focused on intelligent information discovery-finding files and assets that were never meant to see the light of day.

Google Dorking for Leaks:

Why hack a database when the passwords might be on Google?

Google Dorking uses specific search operators to find publicly indexed files that should be private. We learned to combine operators to find:

  • Open directories that list all their contents (intitle:"index of")
  • Sensitive file types like credentials or backups (ext:doc | ext:docx | ext:sql).

Subdomain Takeover (The Unclaimed Asset):

​A high-impact, low-effort finding.

It happens when a subdomain points to an unclaimed third-party service (like a cancelled Heroku or AWS account). An attacker can register that service and take over the domain. We were introduced to SUBZY to automate the detection of this specific, critical vulnerability.

Directory Listing:

​Check for Directory Listing Enabled, which happens when a server lacks an index.html file and exposes directory contents. Navigating to a path like /uploads/ can expose backups (.zip, .sql), credentials, and configuration files.

Logic Flaws and Session Manipulation

True bug hunting requires a diverse toolkit that goes beyond simple web requests.

The tools needed for next-level testing:

​No Rate Limiting:

Check endpoints like login, registration, and OTP to see if they prevent bulk attempts. Sending 100+ requests is the standard test, using tools like Burp Intruder or Turbo Intruder. Without a rate limit (HTTP 429), brute-force, credential stuffing, and OTP bypass are possible.

​Session Management Flaws:

We test if sessions expire properly.

  • ​Test- Login in Incognito tab (A), then change password or logout in a normal tab. If tab (A) still works, the session is not expired.
  • ​Flaws-Session Not Expired After Logout and Session Not Expired After Password Change.​

Response Manipulation:

This involves modifying the HTTP request/response in Burp Suite to see if we can elevate privileges. Check for hidden parameters and change values (e.g., role=user to role=admin) to see if the response status or fields change.

Finalizing the Toolkit and Ethical Rules

​An essential overview of specialized tools and the ethical framework for submission.

Specialized Tools :

  • ​SUBZY - Subdomain takeover automation.
  • ​GOBUSTER / DIRSEARCH / FFUF - Directory/DNS brute force and web fuzzing.
  • ​JADX - APK reverse engineering to Java code.
  • ​GENYMOTION / MOBSF - Android emulator for app testing and static/dynamic mobile app testing.

Reporting and Disclosure:

  • ​Vulnerability Taxonomy- A list of categorized vulnerabilities accepted in most platforms, which includes Web, Mobile, API, Client-side, and Business Logic. This resource helps in understanding valid versus invalid reports.
  • ​Real-World Example- We studied theq scenario, where the flaw could be exploited by brute-forcing the endpoint or intercepting and replaying the verification request.
  • ​Responsible Disclosure-The final rule: Always report through proper channels (security.txt, HackerOne, Bugcrowd, or VDP email), and never exploit, only validate the finding, ensuring no user is harmed.

In summary, Day 3 was the active hunting initiation. We armed ourselves with fuzzing tools and intelligent search methods to map out the entire digital footprint—a huge step toward becoming a full-scope security researcher.