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Introduction:
In the high-stakes world of bug bounty hunting, luck is a poor strategy. Success relies on disciplined methodology, obsessive reconnaissance, and the ability to translate skills from one domain to another. This article deconstructs the approach used by a security researcher who, while balancing a final year of engineering school and a cloud analyst contract, applied athletic training principles to ethical hacking—resulting in a critical CVSS 7.5 vulnerability submission on the YesWeHack platform. We will explore the technical workflows, tooling, and step-by-step commands that turn “obsession” into reproducible bounties.
Learning Objectives:
- Understand how to apply structured methodologies (like athletic training cycles) to bug bounty recon and exploitation.
- Learn the essential Linux/Windows commands and tool configurations for reconnaissance and vulnerability detection.
- Master the documentation process that transforms raw findings into professional, paid reports.
- Identify common API and cloud misconfigurations that lead to high-CVSS scores.
You Should Know:
1. Reconnaissance: The “Pre-Season” Training
The foundation of the €1500 find was not in exploitation, but in exhaustive reconnaissance. Treating recon like an athletic warm-up, the researcher mapped the target’s digital footprint before writing a single line of exploit code. This phase involves gathering subdomains, identifying live hosts, and cataloging APIs.
Step‑by‑step guide (Linux):
This process utilizes common open-source tools to build a target map.
1. Subdomain Enumeration using Assetfinder and Amass assetfinder -subs-only target.com | tee -a subs.txt amass enum -passive -d target.com | tee -a amass_subs.txt <ol> <li>Probing for live hosts and web servers using httpx cat subs.txt amass_subs.txt | sort -u | httpx -silent -websocket -title -tech-detect -status-code -o live_hosts.txt</p></li> <li><p>Crawling the live sites to discover hidden endpoints and parameters katana -list live_hosts.txt -jc -kf all -aff -o endpoints.txt</p></li> <li><p>API endpoint discovery via wayback machine waybackurls target.com | grep -E ".json$|.yaml$|/api/|/v[0-9]/" | tee api_endpoints.txt
What this does: These commands build a comprehensive attack surface. `assetfinder` and `amass` find related domains. `httpx` checks which of those domains are actually hosting web content. `katana` crawls those sites to find every link and endpoint, while `waybackurls` digs up historical API paths that might still be active.
2. Methodology: The “Sprint” and “Iteration” Cycles
Just as an athlete reviews game footage, a bug hunter must iterate on their findings. The key takeaway from the post is the cycle: Read (learn from top researchers), Apply (test immediately), Document (record every command and output). This transforms passive knowledge into muscle memory.
Step‑by‑step guide (Windows – PowerShell):
While Linux is common for recon, Windows environments are crucial for testing Active Directory or client-side bugs. Here is how to automate a basic “sprint” loop for testing a list of URLs for common misconfigurations.
1. Define your target list from the recon phase
$targets = Get-Content .\live_hosts.txt
<ol>
<li>Iterate through each target to test for missing security headers
foreach ($url in $targets) {
Write-Host "Testing: $url" -ForegroundColor Green
try {
$response = Invoke-WebRequest -Uri $url -Method Head -TimeoutSec 5
$headers = $response.Headers
Check for critical security headers
if (-not $headers.ContainsKey("Content-Security-Policy")) {
Write-Host " [!] Missing CSP: $url" -ForegroundColor Yellow
}
if (-not $headers.ContainsKey("X-Frame-Options")) {
Write-Host " [!] Missing XFO: $url" -ForegroundColor Yellow
}
} catch {
Write-Host " [bash] Error connecting to $url" -ForegroundColor Red
}
}</p></li>
<li><p>Automate the logging (Documentation step)
Pipe the output to a file with a timestamp
$timestamp = Get-Date -Format "yyyyMMdd_HHmm"
.\security_header_check.ps1 | Out-File "scan_log_$timestamp.txt"
What this does: This script automates the “Apply” phase. It iterates through your list of live hosts, checks for the presence of essential HTTP security headers, and automatically documents the results. This ensures no finding is lost and allows for easy comparison between “sprints.”
- Vulnerability Exploitation: The IDOR that Became a CVSS 7.5
The specific €1500 bug was a critical vulnerability patched within 24 hours. While the exact details are proprietary, the methodology points towards an Insecure Direct Object Reference (IDOR) or an API authorization flaw, common sources of high-severity issues in cloud/SaaS environments.
Step‑by‑step guide (API Testing with cURL):
After identifying API endpoints (from Step 1), manual manipulation is key.
Scenario: Testing for Horizontal Privilege Escalation in a user profile API
<ol>
<li>Authenticate and capture your valid session token (JWT)
(Assuming you have a test account)
TOKEN="eyJhbGciOiJIUzI1NiIs..."</p></li>
<li><p>Test your own user account to see the normal response structure
curl -X GET https://api.target.com/v1/user/profile/123 \
-H "Authorization: Bearer $TOKEN" \
-H "Content-Type: application/json" \
-w "\nHTTP Status: %{http_code}\n" \
-o response_my_account.json</p></li>
<li><p>Increment the ID parameter to attempt accessing another user's data
This tests for a broken object level authorization
for i in {124..130}; do
echo "Testing User ID: $i"
curl -X GET https://api.target.com/v1/user/profile/$i \
-H "Authorization: Bearer $TOKEN" \
-H "Content-Type: application/json" \
-w "HTTP Status: %{http_code}\n" \
-o "response_user_$i.json"
Quick check to see if the response contains data (and not an error)
if grep -q "email" "response_user_$i.json"; then
echo " [!] Potential IDOR Found! Data retrieved for user $i"
fi
sleep 1 Be polite to the server
done
What this does: This command sequence is the “exploitation” phase. It takes a discovered API endpoint and attempts to manipulate the resource identifier (profile/123). If the API returns data for user 124 using the token of user 123, an IDOR vulnerability is confirmed. This type of flaw directly leads to data breaches and often scores highly on the CVSS scale (7.5 or higher) due to impacts on Confidentiality and Integrity.
4. Cloud Hardening: Preventing the Abuse
For defenders, understanding this methodology is crucial for hardening cloud environments. The attack chain often starts with a misconfigured cloud storage bucket or an overly permissive IAM role.
Step‑by‑step guide (AWS CLI Hardening):
1. Check if an S3 bucket is publicly listable (a common recon target) aws s3api get-bucket-acl --bucket target-company-assets <ol> <li>List the contents if the bucket is public (simulating attacker recon) aws s3 ls s3://target-company-assets/ --no-sign-request</p></li> <li><p>HARDENING: Block all public access to a bucket aws s3api put-public-access-block \ --bucket your-company-secure-bucket \ --public-access-block-configuration BlockPublicAcls=true,IgnorePublicAcls=true,BlockPublicPolicy=true,RestrictPublicBuckets=true</p></li> <li><p>Enforce least privilege on IAM roles Review policies attached to a role aws iam list-attached-role-policies --role-name YourAppRole Detach overly permissive policies (e.g., AdministratorAccess) aws iam detach-role-policy --role-name YourAppRole --policy-arn arn:aws:iam::aws:policy/AdministratorAccess
What this does: The first two commands simulate an attacker’s recon, attempting to find exposed data. The latter two are the defender’s response, locking down the infrastructure to prevent the data leaks that bug bounty hunters are trained to find.
- The Report: Turning a Bug into a Bounty
The final, critical step is documentation. The post emphasizes documenting every session. A bounty is paid not just for finding a bug, but for explaining its impact clearly.
- Vulnerability Name: Insecure Direct Object Reference (IDOR) in User Profile API.
- Endpoint: `GET /api/v1/user/profile/{id}`
– Steps to Reproduce:
1. Log in as user `[email protected]` (User A).
- Intercept the request to `/api/v1/user/profile/456` and capture the
Authorization: Bearer [bash]. - Replace the ID in the request with that of another user, e.g.,
/api/v1/user/profile/789. - Observe that the API returns the full PII data of User B without requiring their credentials.
– Impact: Unauthorized access to all user profiles, leading to mass data breach (Confidentiality High).
– CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N (Base Score: 6.5 or 7.5 depending on scope).
What Undercode Say:
- Key Takeaway 1: Success in bug bounty is a product of process, not luck. The “Obsession Method”—reading, applying, documenting—transforms a casual scanner user into a disciplined security researcher capable of finding logic flaws that automated tools miss.
- Key Takeaway 2: The convergence of skills is real. The discipline used in athletic training, language learning, or content creation provides a perfect framework for cybersecurity research. It proves that soft skills (consistency, documentation, iteration) are just as valuable as technical command knowledge.
The narrative of the student who earned €1500 while balancing a full schedule is a testament to the power of focused, iterative methodology. By treating each target as a new “sport” to master, and by automating the “boring” parts of recon and documentation, the researcher freed up mental energy to focus on the creative exploitation that finds critical bugs. The tools and commands listed here are merely the brush; the obsession is the artist.
Prediction:
As AI-assisted coding becomes standard, the number of API and cloud misconfigurations will initially skyrocket, creating a golden age for bug bounty hunters. However, within 2-3 years, defensive AI will begin to auto-remediate simple flaws like missing headers or public buckets. The future of high-value bug hunting will shift entirely toward complex business logic flaws—vulnerabilities that require human intuition to find—making the “obsessive” methodology described here the only viable path to success.
🎯Let’s Practice For Free:
IT/Security Reporter URL:
Reported By: Bilal Guirre – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
