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Introduction:
The world of bug bounties offers a lucrative and legal pathway for cybersecurity professionals to leverage their hacking skills. By proactively discovering and reporting vulnerabilities in web applications, ethical hackers can earn significant rewards while strengthening digital defenses. This guide provides the essential technical foundation to begin your journey.
Learning Objectives:
- Understand the core methodology and tools used in modern web application penetration testing.
- Learn and apply over 25 verified commands for reconnaissance, vulnerability assessment, and exploitation.
- Develop a structured approach to bug hunting that maximizes efficiency and success rates.
You Should Know:
1. The Art of Passive Reconnaissance
Before touching a target, information gathering is key. Passive reconnaissance uses indirect methods to map out an application’s attack surface without sending any packets to the target’s servers.
Command:
subfinder -d target.com -o subdomains.txt amass enum -passive -d target.com -o amass_subs.txt assetfinder --subs-only target.com | tee assetfinder_subs.txt
Step-by-step guide:
- Install the Tools: These commands use Subfinder, Amass, and Assetfinder. They can be installed on Kali Linux via `sudo apt install subfinder amass` and Go with
go install github.com/tomnomnom/assetfinder@latest. - Run the Commands: Execute each command in your terminal, replacing `target.com` with the actual domain. Each tool uses different data sources (search engines, SSL certificates, archives) to discover subdomains.
- Combine and Sort Results: Merge all found subdomains into one list, remove duplicates, and save for the next phase.
cat subdomains.txt amass_subs.txt assetfinder_subs.txt | sort -u > all_subs.txt
2. Probing for Live Hosts and HTTP Services
With a list of subdomains, the next step is to filter out inactive ones and discover which are running web services.
Command:
httpx -l all_subs.txt -title -status-code -tech-detect -o responsive_hosts.txt
Step-by-step guide:
- Install HTTPX: A versatile tool installed via Go:
go install github.com/projectdiscovery/httpx/cmd/httpx@latest. - Execute Probing: The `-l` flag specifies your list of subdomains. The other flags instruct HTTPX to fetch the page title, HTTP status code, and identify technologies (e.g., WordPress, React, Nginx).
- Analyze Output: The output file (
responsive_hosts.txt) now contains a curated list of active web targets enriched with data, allowing you to prioritize interesting targets (e.g., those with a `200` status code).
3. Discovering Hidden Paths and APIs
Critical vulnerabilities often lie in hidden directories, API endpoints, and configuration files. Fuzzing is the technique used to find them.
Command:
ffuf -w /usr/share/wordlists/dirb/common.txt -u https://target.com/FUZZ -mc 200,301,302,403
Step-by-step guide:
- Install FFUF: Another Go tool:
go install github.com/ffuf/ffuf@latest. - Understand the Flags: `-w` specifies the wordlist (a file containing potential path names). `-u` is the target URL, where `FUZZ` is a placeholder FFuf replaces with words from the list. `-mc` tells FFuf to show responses with these HTTP status codes.
- Run and Interpret: Run the command. FFuf will rapidly test thousands of paths. Pay close attention to responses listing directories like
/admin,/api,/backup, or files like.env,config.json.
4. Automating Vulnerability Scanning
While manual testing is crucial, automated scanners can quickly identify low-hanging fruit and common misconfigurations.
Command:
nuclei -l responsive_hosts.txt -t exposures/ -t vulnerabilities/ -o nuclei_results.txt
Step-by-step guide:
1. Install Nuclei: `go install github.com/projectdiscovery/nuclei/v2/cmd/nuclei@latest`.
- Update Templates: Nuclei uses community-powered templates. Always run `nuclei -update-templates` first.
- Launch the Scan: The `-l` flag takes your list of live hosts. `-t` specifies template categories (e.g., `exposures` for leaked data, `vulnerabilities` for common CVEs). Review the `nuclei_results.txt` file carefully for potential leads.
5. Analyzing JavaScript for Hidden Secrets
Modern web apps heavily use JavaScript, which often contains hardcoded API keys, tokens, and hidden endpoints.
Command:
subjs -i responsive_hosts.txt | tee jsfiles.txt
cat jsfiles.txt | waybackurls | grep -E '.js$' | sort -u > all_js_urls.txt
cat all_js_urls.txt | while read url; do curl -s $url | grep -oE "[a-zA-Z0-9_]{256,}" | sort -u; done > potential_secrets.txt
Step-by-step guide:
- Gather JS Files: Use `subjs` to find JavaScript files linked from your targets. `waybackurls` (from the tomnomnom suite) finds historical URLs, often catching more JS files.
- Extract Patterns: The final command curls each JS file and uses `grep` to extract strings that match the pattern of potential long secrets (like API keys or tokens).
- Validate Findings: Always test any discovered keys against their respective services to check if they are valid and what level of access they grant.
6. Testing for Common Web Vulnerabilities: SQL Injection
SQL Injection (SQLi) remains a top critical vulnerability, allowing attackers to interfere with database queries.
Command:
sqlmap -u "https://target.com/page?id=1" --batch --level=3 --risk=3 --dbs
Step-by-step guide:
- Install SQLMap: Pre-installed on Kali or available via
pip install sqlmap. - Identify a Parameter: Find a URL parameter (like `?id=1` or
?user=admin) that appears to interact with a database. - Run SQLMap: The `-u` flag specifies the target URL. `–batch` runs in non-interactive mode. `–level` and `–risk` increase the depth of tests. `–dbs` attempts to enumerate available databases if a vulnerability is found.
- Caution: Only use this on targets you are explicitly authorized to test. Unauthorized use is illegal.
7. Session Management and Access Control Testing
Testing for broken access control, a top OWASP vulnerability, often involves manipulating session cookies.
Command:
Linux/Mac
curl -H "Cookie: session=invalid_session_value" https://target.com/admin
Windows PowerShell
Invoke-WebRequest -Uri "https://target.com/admin" -Headers @{"Cookie"="session=invalid_session_value"}
Step-by-step guide:
- Understand the Test: This test checks if the application properly validates session tokens. A successful response (e.g., HTTP 200) to an invalid token indicates a flaw.
- Use Burp Suite: Intercept a valid request to a privileged endpoint (e.g.,
/admin) using Burp Suite Proxy. - Modify and Replay: In Burp Repeater, change the session cookie value to something random or blank and send the request. If you are still granted access, you’ve found a critical vulnerability.
What Undercode Say:
- Methodology is King: Tools are useless without a structured approach. Reconnaissance → Enumeration → Vulnerability Analysis → Exploitation → Reporting is the non-negotiable cycle of success.
- Automation is Your Ally: The difference between a beginner and a successful hunter is the ability to automate the boring parts, freeing up time for deep, manual exploitation of complex vulnerabilities.
- The shift towards continuous automated security testing through bug bounty platforms is fundamentally changing how organizations defend themselves. This creates a massive demand for skilled ethical hackers. Success in this field will increasingly depend on a practitioner’s ability to curate and master a personalized toolkit, much like the one outlined here, to find vulnerabilities that automated scanners alone cannot.
Prediction:
The convergence of AI-powered bug hunting assistants and the expanding attack surface of IoT and cloud infrastructure will exponentially increase the scope and value of bug bounty programs. We will see the first-ever million-dollar bounty payout for a single critical vulnerability within the next 3-5 years, cementing ethical hacking as a premier cybersecurity career path.
🎯Let’s Practice For Free:
IT/Security Reporter URL:
Reported By: https://lnkd.in/p/dbvPe6zN – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
