€200 in 24 Hours: How Secret Hunter Uncovered a Hidden Vulnerability – And How You Can Too + Video

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Introduction:

Reconnaissance is the cornerstone of any successful bug bounty hunt – and automation is changing the game. When a new user of Secret Hunter landed a €200 bounty within 24 hours by identifying a valid vulnerability, it proved that efficient, tool‑augmented recon can turn a beginner into a paid researcher overnight. This article dissects the techniques behind Secret Hunter, provides hands‑on commands for JavaScript analysis and endpoint discovery, and offers a complete guide to replicating this success while staying ethical.

Learning Objectives:

  • Master automated reconnaissance using Secret Hunter to identify hidden endpoints and sensitive data leaks.
  • Execute Linux/Windows commands for scalable JavaScript file analysis and secret detection.
  • Implement cloud and API hardening techniques to prevent the very vulnerabilities bug hunters exploit.

You Should Know:

  1. Installing and Configuring Secret Hunter on Linux and Windows
    Secret Hunter is a powerful open‑source tool that scans JavaScript files for exposed endpoints, API keys, tokens, and other sensitive information. It reduces manual effort by automating the extraction and analysis of JS bundles.

Linux Setup:

 Clone the repository
git clone https://github.com/yourrepo/secret-hunter.git  Replace with actual repo if public; otherwise use the tool's official source
cd secret-hunter

Install Node.js dependencies (if written in Node)
npm install

Basic usage – scan a single JS file
node secret-hunter.js -u https://target.com/app.js

Scan a list of JS URLs
cat js_urls.txt | node secret-hunter.js -i -

Windows Setup (PowerShell):

 Clone using git (install Git for Windows first)
git clone https://github.com/yourrepo/secret-hunter.git
cd secret-hunter

Install dependencies
npm install

Run against a target
node secret-hunter.js -u "https://target.com/static/bundle.js"

Step‑by‑step guide:

1. Install Node.js (v14+) and Git.

2. Clone the Secret Hunter repository.

  1. Run `npm install` to fetch required libraries (e.g., axios, cheerio).
  2. Prepare a text file with JavaScript URLs gathered from gospider, hakrawler, or waybackurls.
  3. Execute Secret Hunter with your preferred flags (e.g., --output findings.json).
  4. Review the results – each finding includes the file name, line number, and matched secret pattern.

  5. Analyzing JavaScript Files for Hidden Endpoints and Secrets
    Modern web applications pack business logic into client‑side JS. Attackers can find internal API endpoints, debugging interfaces, and even hard‑coded credentials.

Using Secret Hunter effectively:

 Recursively fetch all JS files from a domain using gau + hakrawler
echo "target.com" | gau --subs --js | tee js_files.txt

Run Secret Hunter on the list
secret-hunter -l js_files.txt -o secrets.json

Grep for specific patterns (e.g., AWS keys, JWT tokens)
cat secrets.json | grep -E "AKIA[0-9A-Z]{16}|eyJhbGciOiJ"

Manual extraction with Linux tools:

 Download a JS file and search for API endpoints
curl -s https://target.com/main.js | grep -Eo "(https?://[a-zA-Z0-9./?=_-])" | sort -u

Find potential secret keys (high entropy strings)
strings main.js | grep -E "[a-zA-Z0-9+/]{40,}" | head -20

Windows PowerShell alternative:

(Invoke-WebRequest -Uri "https://target.com/app.js").Content | Select-String -Pattern "https?://[a-zA-Z0-9./?=<em>-]" -AllMatches | ForEach-Object {$</em>.Matches.Value} | Sort-Object -Unique

Step‑by‑step guide:

  1. Collect all JS URLs using gau, waybackurls, or katana.

2. Filter for `.js` extensions and unique entries.

  1. Run Secret Hunter to automate pattern matching for over 100+ secret types (Slack tokens, Google API keys, etc.).
  2. Manually verify false positives – many “secrets” are sample strings or commented code.
  3. For confirmed leaks, document the endpoint, impact, and remediation.

3. Automating Reconnaissance with Bash and PowerShell

Speed wins bounties. Combining Secret Hunter with parallel processing lets you scan hundreds of JS files in minutes.

Linux Bash automation:

!/bin/bash
 recon.sh – Automated JS secret hunting
DOMAIN=$1
echo "[] Gathering JS URLs for $DOMAIN"
echo $DOMAIN | gau --subs --js | sort -u > js_list.txt

echo "[] Scanning with Secret Hunter"
while read url; do
secret-hunter -u "$url" -o "output/$(echo $url | md5sum | cut -d' ' -f1).json"
done < js_list.txt

Aggregate findings
jq '.findings[]' output/.json > all_secrets.txt

Parallel execution with GNU parallel:

cat js_list.txt | parallel -j 10 'secret-hunter -u {} -o {}.json'

Windows PowerShell with parallel jobs:

$urls = Get-Content js_list.txt
$urls | ForEach-Object -Parallel {
secret-hunter -u $_ -o "$([System.Guid]::NewGuid()).json"
} -ThrottleLimit 5

Step‑by‑step guide:

1. Create a working directory for each target.

  1. Use `gau` (getallurls) to fetch historical JS URLs from AlienVault, Wayback, etc.

3. Remove duplicates with `sort -u`.

  1. Launch parallel jobs – each job runs Secret Hunter on one JS file.
  2. Combine JSON outputs into a single report using jq.

4. API Security: Hardening Against Secret Leakage

If you find a secret, you must also understand how to fix it. Most leaks occur because developers embed keys directly in client‑side code or commit them to public repositories.

Mitigation strategies with Linux commands:

 Scan your own Git history for secrets
git log -p | grep -E "(api_key|secret|token|password) = ['\"][a-zA-Z0-9]{16,}"

Set up pre-commit hooks to block secrets
 Install truffleHog
docker run -it -v "$PWD:/pwd" trufflesecurity/trufflehog:latest git file:///pwd

API gateway hardening (example with Nginx):

 Block direct access to /internal/ endpoints from client-side JS
location /internal/ {
allow 10.0.0.0/8;
deny all;
 Require API key in header (not in URL)
if ($http_x_api_key !~ "^(expected-hash)$") { return 403; }
}

Step‑by‑step guide for developers:

  1. Never store secrets in JavaScript bundles – use environment variables or a backend proxy.
  2. Implement Content Security Policy (CSP) to restrict where JS can send data.
  3. Run `secret-hunter` against your own staging environment before release.
  4. Use secret scanning tools like GitLeaks or Gitleaks in CI/CD pipelines.
  5. Rotate any leaked keys immediately via cloud console or CLI.

5. Cloud Hardening: IAM Roles and Key Rotation

Many bounties involve exposed AWS, Azure, or GCP keys. Proper IAM hygiene prevents these findings from becoming critical.

AWS CLI commands to secure keys:

 List all IAM users and their access keys
aws iam list-users --query 'Users[].UserName' --output text | while read user; do
aws iam list-access-keys --user-name $user
done

Delete a compromised key
aws iam delete-access-key --user-name victim --access-key-id AKIA...

Create a new key and update application
aws iam create-access-key --user-name victim

Azure PowerShell equivalent:

 List all service principals with secrets
Get-AzADServicePrincipal | ForEach-Object {
Get-AzADAppCredential -ObjectId $_.Id
}

Rotate key vault secrets
$secret = Get-AzKeyVaultSecret -VaultName "myvault" -Name "api-key"
$newSecret = Set-AzKeyVaultSecret -VaultName "myvault" -Name "api-key" -SecretValue (ConvertTo-SecureString "NewKey123!" -AsPlainText -Force)

Step‑by‑step guide:

  1. Enforce least privilege – give only the permissions absolutely required.
  2. Set up automatic key rotation (every 90 days) using AWS Lambda or Azure Automation.
  3. Monitor CloudTrail logs for unusual API calls from new IPs.
  4. Use `aws configure` to set temporary credentials via STS instead of long‑term keys.
  5. For GitHub/Action secrets, use OpenID Connect (OIDC) instead of storing keys.

6. Vulnerability Exploitation and Responsible Disclosure

Once Secret Hunter finds a leak, you must responsibly disclose it. The €200 bounty was paid because the researcher followed proper channels.

Reporting steps:

  1. Reproduce the issue – confirm the secret is active and not a honeytoken.

2. Write a clear Proof of Concept (PoC):

 Example PoC for an exposed Firebase API key
curl -X POST https://your-project.firebaseio.com/users.json?auth=LEAKED_KEY \
-d '{"test":"data"}'

3. Estimate impact (e.g., data breach, account takeover, privilege escalation).
4. Send report via HackerOne, Bugcrowd, or the program’s own portal.
5. Include a remediation suggestion: “Rotate the key and move to server‑side proxy.”

CVE assignment (if applicable):

  • The post mentions CVE-2025-55129 – researchers can request CVEs for novel vulnerabilities.
  • Use `cveform.mitre.org` to submit, providing technical details and affected versions.

Step‑by‑step guide:

  1. Do not publicly disclose the secret – no screenshots or public posts.
  2. Encrypt communication if the program provides a PGP key.
  3. Wait for the vendor to fix and acknowledge the finding.
  4. After public disclosure (if allowed), you may write a blog post or share the CVE.

7. Integrating Secret Hunter with Other Recon Tools

Professional workflows combine Secret Hunter with Nuclei, ffuf, and Burp Suite for end‑to‑end testing.

Automated pipeline example:

 Step 1: Subdomain enumeration
subfinder -d target.com -o subs.txt

Step 2: HTTP probing
httpx -l subs.txt -o live.txt

Step 3: Crawl JS files
katana -u https://target.com -jc -o crawler_output.txt

Step 4: Extract JS endpoints
cat crawler_output.txt | grep ".js" > final_js.txt

Step 5: Secret Hunter + Nuclei for validation
secret-hunter -l final_js.txt -o secrets.txt
nuclei -l live.txt -t exposures/configs/ -o nuclei_hits.txt

Step 6: Fuzz hidden parameters on found endpoints
ffuf -u https://target.com/api/FUZZ -w /usr/share/wordlists/api_common.txt

Step‑by‑step integration guide:

1. Run subdomain enumeration and live host detection.

  1. Crawl each live host with `katana` or gospider.
  2. Filter for JavaScript URLs and feed them to Secret Hunter.

4. Validate any discovered secrets using Nuclei templates.

  1. For endpoints without secrets, fuzz for parameter injection with ffuf.
  2. Send the final validated list to Burp Suite for manual testing.

What Undercode Say:

  • Speed + automation = bounties. The €200 in 24 hours proves that even a beginner with the right tool can beat manual hunters.
  • Tool amplification, not replacement. Secret Hunter doesn’t think like a hacker – you still need to verify false positives and craft PoCs.
  • JavaScript is the new attack surface. Every modern web app leaks internal routes and logic through client‑side bundles.
  • Defenders must think like attackers. Run Secret Hunter against your own assets before someone else does.
  • The disclosure pipeline is critical. Without responsible reporting, a €200 bounty becomes a €0 liability.

Prediction:

As client‑side JavaScript continues to grow in complexity (think React, Vue, and SPA frameworks), automated secret hunters will become standard in every bug bounty toolkit. Within the next 12 months, expect to see Secret Hunter‑like features integrated directly into Burp Suite and ZAP. Simultaneously, companies will adopt real‑time secret scanning in their build pipelines, and CSP policies will become stricter – raising the bar for recon. Researchers who master these tools today will dominate the bounty leaderboards of tomorrow.

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