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Introduction:
Bug bounty hunting represents the front line of modern cybersecurity, where ethical hackers identify vulnerabilities before malicious actors can exploit them. Platforms like HackerOne provide structured programs that allow security researchers to test applications and earn rewards for valid discoveries, bridging the gap between external security research and corporate defense mechanisms.
Learning Objectives:
- Understand the workflow of selecting and engaging with a HackerOne program, differentiating between external and targeted program scopes.
- Learn to identify, classify, and report common web vulnerabilities such as information disclosure and low-impact logic flaws.
- Master the use of reconnaissance, automation, and reporting tools to increase the efficiency and validity of bug submissions.
You Should Know:
- The Hunt: From Program Selection to Report Submission
The journey of a bug bounty hunter often begins with strategic program selection. Mohamed AboElshikh’s approach, focusing initially on external programs before committing to a specific HackerOne target, highlights a crucial methodology. When selecting a program, prioritize those with clear scopes, active response histories, and manageable targets for your skill level. Starting with “external programs” often means engaging with public bug bounty programs where the scope is broad, allowing for diverse testing. Transitioning to a specific program requires deep diving into its assets: web applications, API endpoints, and mobile interfaces.
Step‑by‑step guide explaining what this does and how to use it:
1. Reconnaissance (Linux): Use tools like `subfinder` and `amass` to enumerate subdomains of your target.
subfinder -d target.com -o subdomains.txt amass enum -d target.com -o amass_subs.txt cat subdomains.txt amass_subs.txt | sort -u | httpx -silent -o live_hosts.txt
What this does: It discovers all publicly accessible subdomains associated with the target. `httpx` then filters only live hosts, reducing your attack surface.
2. Technology Fingerprinting (Linux): Identify the technologies used by the live hosts.
cat live_hosts.txt | httpx -tech-detect -silent -o tech_results.txt
What this does: This helps you tailor your testing. If you see a specific CMS or framework (like WordPress, Django, or Node.js), you can focus on known vulnerabilities for that stack.
3. Manual and Automated Testing: Begin with automated scanners for low-hanging fruit, then pivot to manual testing for logic flaws. For a web application, use Burp Suite to intercept and modify requests. For instance, test for parameter pollution by adding duplicate parameters in a request.
Original: GET /profile?user_id=123 Modified: GET /profile?user_id=123&user_id=456
What this does: This tests for IDOR (Insecure Direct Object Reference) and logic flaws where the application might mishandle conflicting inputs, potentially returning another user’s data.
4. Reporting: Structure your report with a clear title, severity rating (based on CVSS v3.1), step-by-step reproduction steps, proof of concept (PoC), and impact assessment. A “Low – Accepted and Valid” report, like Mohamed’s, often stems from a logic flaw or information disclosure that doesn’t directly lead to system compromise but still poses a risk.
2. Mastering Vulnerability Classifications: Duplicates, Informative, and Valid
In the bug bounty ecosystem, not all submissions are created equal. Mohamed’s bounty breakdown—one High (Duplicate), two Informative, and one Low (Valid)—reflects a common reality for hunters. A “High – Duplicate” indicates you found a significant issue, but someone else reported it first, emphasizing the importance of speed and thorough prior research. “Informative” reports are often low-risk issues that may not warrant a bounty but provide value to the organization. The “Low – Accepted and Valid” report is the tangible reward for persistence.
Step‑by‑step guide explaining what this does and how to use it:
1. Avoiding Duplicates: Before reporting, search the program’s disclosure policy and existing reports (if public) or use `site:hackerone.com target` in Google to see if a similar issue has been publicly discussed.
Search for known vulnerabilities in the target's scope using tools like searchsploit searchsploit target software version
What this does: This checks the Exploit-DB database for known exploits against technologies used by the target, helping you identify if a vulnerability you found is already public.
2. Elevating Informative to Low/Medium: If you find an informative issue like a reflected self-XSS (Cross-Site Scripting), test if it can be escalated.
– Windows/Linux (Browser DevTools): Open the browser’s Developer Tools, go to the “Network” tab, and intercept the request. See if the XSS payload can be injected in a `POST` body instead of GET, and if it gets stored (Stored XSS).
– Command for PoC: Use `curl` to simulate a persistent payload.
curl -X POST -d "comment=<script>alert('XSS')</script>" https://target.com/post_comment -H "Cookie: session=YOUR_SESSION"
What this does: This elevates a trivial reflective XSS to a stored XSS, which usually carries a higher severity and is less likely to be dismissed as informative.
3. Validating Low Severity Issues: A valid low report often involves misconfigurations or information leaks. Use tools like `nmap` to scan for open ports that shouldn’t be public.
nmap -sV -p- target.com -oN nmap_scan.txt
What this does: Identifies services like an exposed Redis (port 6379) or MongoDB (port 27017) without authentication. Documenting this misconfiguration as a low-severity information disclosure is a valid finding.
3. API Security and Cloud Hardening
Many modern bug bounties focus on APIs, which are often overlooked. An API misconfiguration can lead to mass data exposure. Cloud hardening is equally critical, as misconfigured S3 buckets or Azure Blob Storage can expose sensitive data. Given the “External Program” focus, this is a prime area for discovery.
Step‑by‑step guide explaining what this does and how to use it:
1. API Reconnaissance: Use `ffuf` (Fuzz Faster U Fool) to discover hidden API endpoints.
ffuf -w /usr/share/wordlists/seclists/Discovery/Web-Content/common-api-endpoints-master.txt -u https://target.com/api/FUZZ -c -t 100
What this does: It fuzzes the `/api/` directory with a wordlist to discover undocumented API endpoints that might be vulnerable to IDOR or information disclosure.
2. Testing for Mass Assignment: Intercept an API request that updates a user profile (e.g., PUT /api/user/123). Add a `”is_admin”: true` field to the JSON body.
{
"username": "attacker",
"email": "[email protected]",
"is_admin": true
}
What this does: If the API accepts and processes the `is_admin` field, it’s vulnerable to mass assignment, a critical flaw often found in API endpoints.
3. Cloud Bucket Hardening Check (Linux): Use `bucket_finder` or manual methods to check for public S3 buckets.
Check if a bucket is public and list its contents aws s3 ls s3://target-bucket-name/ --no-sign-request
What this does: Attempts to list the contents of an S3 bucket without authentication. If successful, you’ve discovered a significant data leak. Report this immediately.
4. Automation and Tooling for Efficiency
To maximize success in bug bounty, automation is key. Tools like Nuclei, a fast vulnerability scanner, can be used to automate the detection of known vulnerabilities across your discovered hosts.
Step‑by‑step guide explaining what this does and how to use it:
1. Install Nuclei (Linux):
go install -v github.com/projectdiscovery/nuclei/v3/cmd/nuclei@latest
2. Run Nuclei on Live Hosts:
cat live_hosts.txt | nuclei -t ~/nuclei-templates/ -severity low,medium,high,critical -o nuclei_results.txt
What this does: This runs a scan using a vast community-driven template library against your live hosts, flagging potential vulnerabilities based on fingerprinting. This helps identify low-hanging fruit like misconfigured CORS, exposed admin panels, or outdated software versions.
3. Custom Automation Script (Python): Create a simple script to automate the initial check for `robots.txt` and sitemap.xml, which can reveal hidden directories.
import requests
hosts = open('live_hosts.txt').readlines()
for host in hosts:
host = host.strip()
for path in ['/robots.txt', '/sitemap.xml']:
url = host + path
r = requests.get(url)
if r.status_code == 200:
print(f"[+] Found: {url}")
What this does: This simple script automates the tedious process of checking for common information-disclosure files across all your discovered hosts.
- The Art of Write-Up Creation and Knowledge Sharing
Mohamed’s plan to “write a detailed write-up about the last bug” is a crucial step in a hacker’s growth. A well-crafted write-up solidifies your understanding, helps the community, and can even attract attention from companies seeking talent.
Step‑by‑step guide explaining what this does and how to use it:
1. Document the Discovery: Write down the entire process from the moment you identified the vulnerability. Include the exact HTTP requests and responses.
2. Create a PoC: For a web vulnerability, create a simple HTML file to demonstrate the exploit.
<!DOCTYPE html>
<html>
<body>
<script>
// Example for CSRF PoC
fetch('https://target.com/api/change_email', {
method: 'POST',
credentials: 'include',
body: '[email protected]'
});
</script>
</body>
</html>
What this does: This provides a clear, demonstrable example of the vulnerability that a developer or security team can use to verify the issue.
3. Publish: Share your write-up on platforms like Medium, GitHub, or personal blogs. Use tools like `markdown` to structure the document with code blocks, screenshots, and a timeline.
What Undercode Say:
- Persistence is Key: A junior hunter bagging four bugs, including a duplicate high and a valid low, underscores that success in bug bounty is a numbers game built on persistence and consistent methodology.
- Diversify Your Portfolio: Hunting across external programs allows for broader experience and serendipitous discoveries before committing to a single target for deep, focused testing.
- Documentation is a Skill: The distinction between a duplicate, informative, and valid report often lies not just in the bug itself, but in how well it is documented, communicated, and contextualized for the security team.
Prediction:
The trend of focusing on “External Programs” will continue to grow as more companies embrace crowdsourced security. For aspiring hunters, the ability to seamlessly switch between automated tools and manual logic testing will be the defining skill. Furthermore, as APIs and cloud infrastructures become the backbone of modern applications, bug bounty hunters with expertise in API security, serverless misconfigurations, and cloud identity and access management (IAM) will find themselves in high demand, commanding higher bounties and recognition. The future of bug bounty is not just about finding vulnerabilities, but about proving their business impact with precise, well-articulated reports.
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IT/Security Reporter URL:
Reported By: Mohamed Aboelshikh – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
