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Introduction:
Bug bounty programs have transformed cybersecurity, allowing ethical hackers to earn significant rewards by discovering vulnerabilities in major platforms. The recent LinkedIn post by Vikash Gupta (Founder/CEO of Cywer Learning) teases “Some Bounty & Some Deals & Some Bonus 😀” with a link to a full write-up, emphasizing persistence and a hunter’s mindset. This article extracts the core techniques, tools, and commands from that bounty-hunting ecosystem, providing a step‑by‑step technical guide for both beginners and seasoned pentesters.
Learning Objectives:
- Master reconnaissance and subdomain enumeration workflows used by top bug bounty hunters.
- Execute automated vulnerability scanning and manual exploitation chains on web and API targets.
- Write professional reports and collaborate via platforms like HackerOne and Bugcrowd.
You Should Know:
1. Reconnaissance: Subdomain Enumeration & OSINT
Recon is the foundation of every successful bug bounty hunt. Attackers often find forgotten subdomains that host vulnerable services. Below are verified Linux commands (and Windows equivalents) to discover assets tied to a target domain.
Linux Commands:
Install tools (Ubuntu/Debian) sudo apt install amass subfinder assetfinder httprobe Subdomain enumeration subfinder -d example.com -o subs.txt assetfinder --subs-only example.com >> subs.txt amass enum -passive -d example.com -o amass_subs.txt Probe for live hosts cat subs.txt | httprobe -c 50 -t 3000 > live_hosts.txt
Windows (PowerShell) equivalent:
Using Invoke-SubdomainDiscovery (PowerShell script)
Import-Module ./Invoke-SubdomainDiscovery.ps1
Invoke-SubdomainDiscovery -Domain example.com -OutputFile subs.txt
Test live hosts with Test-NetConnection
Get-Content subs.txt | ForEach-Object { if(Test-NetConnection $_ -Port 80 -InformationLevel Quiet) { Write-Output $_ } }
Step‑by‑step guide:
- Enumerate subdomains using passive sources (security trails, crt.sh, DNS datasets).
2. Merge and deduplicate outputs with `sort -u`.
- Use `httprobe` or `curl -I` to filter only responsive HTTP/HTTPS services.
- Screenshot each live host using `gowitness` to quickly spot interesting login portals or admin panels.
2. Vulnerability Scanning with Nuclei & Nmap
Nuclei is the industry standard for template‑based scanning, while Nmap handles port and service discovery. Both are essential for finding low‑hanging fruit.
Installation & Basic Scan:
Install Nuclei (Linux) go install -v github.com/projectdiscovery/nuclei/v3/cmd/nuclei@latest Update templates nuclei -update-templates Scan a live host for critical vulnerabilities nuclei -u https://target.com -t critical-severity/ -o nuclei_crit.txt Nmap aggressive service scan nmap -sV -sC -p- -T4 target.com -oA nmap_scan
Windows (using WSL or native nmap):
nmap.exe -sV -sC -p 80,443,8080 -oN nmap_scan.txt target.com
Step‑by‑step guide:
- Run Nmap to discover open ports and service versions (look for outdated software).
- Identify technologies using `whatweb` or Wappalyzer browser extension.
- Launch Nuclei with tags like
cve,misconfiguration,exposed-panels. - Manually verify false positives – many automated findings are not exploitable.
- Chain a low‑severity info leak (e.g., exposed
.git/config) with a high‑severity exploit.
3. Web Parameter Fuzzing with ffuf & Gobuster
Fuzzing reveals hidden parameters, directories, and files that may lead to IDOR, SQLi, or XSS. This is where bug bounty hunters spend hours.
Linux fuzzing commands:
Directory fuzzing with common wordlist ffuf -u https://target.com/FUZZ -w /usr/share/wordlists/dirb/common.txt -c -t 100 Parameter fuzzing (GET) ffuf -u https://target.com/page.php?FUZZ=test -w params.txt -fs 0 Recursive gobuster (slower but thorough) gobuster dir -u https://target.com -w /usr/share/wordlists/dirbuster/directory-list-2.3-medium.txt -t 50 -x php,html,txt
Windows with gobuster.exe:
gobuster.exe dir -u https://target.com -w C:\wordlists\common.txt -x .php,.asp
Step‑by‑step guide:
1. Obtain high‑quality wordlists (SecLists, Assetnote).
- Fuzz for directories first – look for admin, api, backup, dev.
- Then fuzz parameters on pages that accept user input (search, filter, profile).
- Monitor response size and status codes – a 200 with unusual length may indicate a hidden parameter.
- Automate with bash loop: `for param in $(cat params.txt); do curl “https://target.com/page?$param=test” -s -o /dev/null -w “%{http_code}\n”; done`
- API Security Testing: Postman, Burp Suite, and Custom Scripts
Modern web apps rely heavily on APIs. Improper authorization and mass assignment are top bounty sources.
Using Burp Suite (Community):
- Set up Burp as a proxy and navigate the target app to map API endpoints.
- Send requests to Repeater and change HTTP methods (GET→POST→PUT→DELETE).
- Test for IDOR by incrementing IDs in parameters: `GET /api/user/1234` → try
/api/user/1235. - Use Autorize extension to detect broken access control.
Custom Python script for API fuzzing:
import requests
url = "https://target.com/api/v1/users"
headers = {"Authorization": "Bearer YOUR_TOKEN"}
for uid in range(1000, 2000):
r = requests.get(f"{url}/{uid}", headers=headers)
if r.status_code == 200 and "email" in r.text:
print(f"IDOR found: {uid} -> {r.text[:100]}")
Step‑by‑step guide:
- Capture all API traffic via Burp or browser dev tools.
- Check for GraphQL endpoints – use `graphql-ide` or `InQL` scanner.
- Attempt to bypass rate limiting by adding `X-Forwarded-For` headers.
- Test for mass assignment by sending extra JSON fields (
"is_admin": true). - Always verify that the API respects authentication tokens – try removing the header.
5. Privilege Escalation & Exploitation (Linux/Windows)
If you gain low‑privileged shell access via a bug (e.g., RCE in a web app), escalate to root or SYSTEM. These commands are essential for post‑exploitation.
Linux privilege escalation checks:
Find SUID binaries find / -perm -4000 -type f 2>/dev/null Check sudo rights for current user sudo -l Kernel version (look for known exploits) uname -a Writable cron jobs ls -la /etc/cron
Windows privilege escalation (PowerShell):
Show unquoted service paths wmic service get name,displayname,pathname,startmode | findstr /i "auto" | findstr /i /v "C:\Windows\" List installed patches wmic qfe list brief Check for AlwaysInstallElevated reg query HKCU\SOFTWARE\Policies\Microsoft\Windows\Installer /v AlwaysInstallElevated
Step‑by‑step guide:
- After obtaining a shell, run `linpeas.sh` (Linux) or `winPEAS.exe` (Windows) for automated enumeration.
- Look for outdated software with known CVEs (e.g., sudo 1.8.27, Dirty Pipe).
- If you find a writable service binary, replace it with a reverse shell.
- For Docker environments, try to escape via `–privileged` mounts or `cgroup` release_agent.
- Document each step with screenshots – bounty reports require proof of impact.
6. Reporting & Collaboration (HackerOne/Bugcrowd)
A vulnerability without a clear report is worth nothing. Professional reports get paid faster.
Recommended report template (Markdown):
[Brief description, e.g., IDOR on /api/v1/invoice] Severity: High (P2) Steps to Reproduce: 1. Login as user A (email: [email protected]) 2. Send GET request to `/api/invoice?invoice_id=1234` – returns invoice of user A. 3. Change ID to 1235 – returns invoice of user B, including PII. Impact: Unauthorized access to any user's invoice data, leading to privacy breach and potential financial data exposure. Proof of Concept: [Attach screenshot or curl command] curl -H "Authorization: Bearer <token>" https://target.com/api/invoice?invoice_id=1235 Suggested Fix: Implement server‑side authorization check – verify that the authenticated user owns the invoice ID.
Step‑by‑step guide:
- Use HackerOne’s “Draft Report” feature to save progress.
- Re‑test the vulnerability after clearing cookies/using a different browser to ensure reproducibility.
- Do not disclose the bug publicly until the program’s disclosure policy allows.
- If a duplicate, politely ask the triager for the original report ID to learn.
- Keep communication professional – bounty hunters often build long‑term relationships.
7. Automation with Bash/Python for Bug Bounty
Automate the boring parts so you can focus on logic flaws.
Simple recon automation script (recon.sh):
!/bin/bash domain=$1 echo "[+] Enumerating subdomains for $domain" subfinder -d $domain -silent > subs.txt assetfinder --subs-only $domain >> subs.txt sort -u subs.txt -o subs.txt echo "[+] Probing live hosts" cat subs.txt | httprobe -c 50 > live.txt echo "[+] Running Nuclei on live hosts" nuclei -l live.txt -t cves/ -o nuclei_output.txt echo "[+] Done. Check nuclei_output.txt"
Run with: `chmod +x recon.sh && ./recon.sh example.com`
Step‑by‑step guide:
- Schedule this script via cron to run daily against your target scope (if permitted).
- Use `jq` to parse JSON outputs from tools like
httpx. - Integrate with Slack or Discord webhooks to receive new findings instantly.
- Always respect the program’s rate limits – add `-t 10` (10 threads) to avoid being blocked.
- Store results in a structured database (SQLite) for trend analysis.
What Undercode Say:
- Persistence over power – The top bounty hunters run recon daily, not just once. Small changes in a target’s infrastructure (new subdomains, updated APIs) are where hidden bugs live.
- Toolchains are multipliers, not magic – Nuclei, ffuf, and Burp are useless without manual thinking. The biggest bounties come from chaining a low‑severity info leak with a business logic flaw.
- Reporting is half the reward – A medium‑severity bug written clearly with reproducible steps and impact analysis gets paid faster than a critical one buried in messy notes.
Prediction:
By 2027, AI‑powered autonomous agents will automatically find and patch low‑hanging vulnerabilities (XSS, SQLi, outdated components) within minutes of code deployment. This will force bug bounty hunters to shift entirely to business logic flaws, race conditions, and AI‑model poisoning attacks – areas where human creativity still outperforms machines. Platforms like HackerOne will introduce “Logic Bounty” tiers with 5x higher payouts for non‑automated bugs, and training courses will pivot from tool usage to adversarial thinking and red‑teaming AI systems.
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IT/Security Reporter URL:
Reported By: Vikas Gupta63 – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
