Listen to this Post
Introduction:
The landscape of web application security is often dominated by discussions of automated vulnerability scanners and complex toolchains. However, a seasoned bug bounty hunter’s recent return to the field after a year-long hiatus serves as a powerful reminder of a fundamental truth: foundational manual testing skills remain the most effective weapon in a security researcher’s arsenal. Within the first seven minutes of resuming testing, and without deploying a single automated scanning tool, multiple vulnerabilities were uncovered, highlighting that while tools assist, human intuition, pattern recognition, and deep technical knowledge are irreplaceable for uncovering complex business logic flaws.
Learning Objectives:
- Understand the importance of manual reconnaissance and how to structure an initial assessment without relying on automated scanners.
- Identify and exploit common web vulnerabilities (such as IDOR, XSS, and misconfigurations) using manual techniques.
- Learn practical Linux/Windows commands and browser-based methods to accelerate manual bug hunting workflows.
You Should Know:
- The Art of Manual Reconnaissance: Rebuilding Your Attack Surface
The post emphasizes that the initial success came from “without alat scanning” (without scanning tools). This approach forces a hunter to rely on pure technical skill. The first step in any manual assessment is mapping the application’s attack surface through meticulous enumeration. This involves analyzing the application’s structure, JavaScript files, and API endpoints directly from the browser.
Step-by-step guide to manual recon:
- Browser Developer Tools (F12): Start by opening the browser’s developer tools. Navigate to the “Network” tab. Clear existing logs, then interact with the application (login, search, click buttons). Analyze every HTTP request.
– Focus on: API endpoints (e.g., /api/v1/users/123), parameters, cookies, and hidden inputs.
2. View Page Source: Right-click the webpage and select “View Page Source.” Search for href=, src=, or embedded JSON data that might reveal commented-out endpoints or development artifacts.
3. JavaScript Analysis: Large JavaScript files often contain commented-out API routes or sensitive logic. In Linux/macOS, you can fetch and search:
Fetch the main JS bundle and grep for endpoints curl -s https://target.com/static/main.js | grep -oP 'https?://[^"]+' | sort -u
On Windows (PowerShell):
Invoke-WebRequest -Uri "https://target.com/static/main.js" | Select-Object -ExpandProperty Content | Select-String -Pattern 'https?://[^"]+' -AllMatches
4. Directory/File Fuzzing (Manual/Simple): Instead of running a full scanner like Dirb or Gobuster immediately, manually guess common endpoints (e.g., /admin, /api/v2/swagger, /backup.zip) using the browser’s address bar or `curl` to test for quick wins.
2. Low-Hanging Fruit: Manual IDOR and Parameter Tampering
The “vulnerability” found likely includes Insecure Direct Object References (IDOR). Since the hunter wasn’t running a scanner, they were manually manipulating identifiers in the URL or POST data. IDORs are often overlooked by automated scanners because they require context—understanding who the object belongs to.
Step-by-step guide to manual IDOR testing:
- Identify Object References: Look for numeric or UUID identifiers in the URL (e.g.,
invoice?id=1001) or in JSON bodies ({"user_id": "123"}). - Create Two Accounts: To test authorization properly, you need two accounts (Account A and Account B). Log into Account A and access a resource (e.g., profile settings). Log into Account B in a separate browser session.
3. Manipulate the Request:
- Take the request from Account A (e.g.,
GET /profile/view?user_id=123). - Using a proxy like Burp Suite (in manual mode) or simply the browser’s dev tools, change the `user_id` parameter to the ID of Account B (
124). - If the server returns Account B’s data while you are authenticated as Account A, you have found a critical IDOR.
- Advanced Manual Tampering: If the ID is hashed (e.g.,
MjQ=), decode it. In Linux:echo "MjQ=" | base64 --decode
This reveals
24. Try sending `25` encoded (MjU=) to test for predictable encoding.
3. XSS Without Automated Scanners: Manual Payload Crafting
Cross-Site Scripting (XSS) is another category where manual testing often yields results that scanners miss, especially in complex, multi-step forms or when filters require creative bypasses.
Step-by-step guide to manual XSS discovery:
- Identify Input Vectors: Locate every input field (search bars, comment sections, URL parameters, file upload names).
- Use Simple Payloads: Start with
<script>alert(1)</script>. If it’s filtered, try different contexts. - Context Matters: Manually inspect the HTML output (F12 -> Elements tab) to see where your input is being placed.
– Inside an HTML tag attribute: `”>`
– Inside a JavaScript block: `’; alert(1);//`
4. Filter Bypass Techniques: If WAF or filters block common tags, try:
– ``
– `
4. Leveraging Linux/Windows for Stealthy Manual Testing
To maintain the “manual” ethos while enhancing efficiency, using native command-line tools can be faster than setting up heavy frameworks.
Linux Commands for Manual Testing:
Check for open ports or service banners manually (without nmap scans) nc -zv target.com 80 443 Manual SSL/TLS check openssl s_client -connect target.com:443 -tlsextdebug Simple API call with custom header curl -X GET "https://target.com/api/secret" -H "Authorization: Bearer <token>" -v
Windows PowerShell for Manual Testing:
Test if a host is reachable and see the response headers
Invoke-WebRequest -Uri "https://target.com" -UseBasicParsing | Select-Object Headers
Check for HTTP methods
$methods = @('GET', 'POST', 'PUT', 'DELETE', 'OPTIONS')
foreach ($method in $methods) {
try {
Invoke-WebRequest -Uri "https://target.com" -Method $method -UseBasicParsing -ErrorAction SilentlyContinue
Write-Host "$method is allowed"
} catch {}
}
5. API Security: Manual Endpoint Analysis
Modern web applications are driven by APIs. Manual API testing involves dissecting the documentation (Swagger/OpenAPI) or capturing traffic to understand the structure.
Step-by-step guide to manual API testing:
- Find the Spec: Look for
/swagger,/v3/api-docs, or `/graphql` endpoints. - Analyze GraphQL: If the site uses GraphQL, manually query the introspection endpoint (if enabled) to map out the entire schema without a scanner.
Manual introspection query { __schema { types { name fields { name } } } } - Parameter Pollution: Manually send duplicate parameters (e.g.,
id=1&id=2) to see if the server mishandles the first or second value, potentially leading to logic flaws.
What Undercode Say:
- Skill Decay is a Myth: The hunter’s success after a one-year break demonstrates that core security skills—like critical thinking and understanding of web mechanics—are deeply ingrained and do not degrade with time; they simply require a catalyst to reactivate.
- Manual > Automated: While automation is useful for scale, manual testing provides context. The initial 7-minute success was likely due to identifying a business logic flaw or misconfiguration that an automated scanner would have misclassified as a false negative.
- The Comeback Strategy: For returning hunters, the methodology should be: 1) Revisit basics with manual recon. 2) Focus on the application’s unique functionality rather than running standard scanner templates. 3) Use lightweight tools (curl, browser dev tools) to validate assumptions quickly.
Prediction:
The future of bug bounty will see a bifurcation: AI-powered scanners will handle the low-hanging fruit, forcing elite hunters to specialize even more deeply in manual, context-dependent vulnerabilities like complex access control flaws, race conditions, and business logic abuse. The hunter’s ability to “think” like a developer and architect will become the premium skill, making manual testing not obsolete, but more valuable than ever. As platforms evolve, we will likely see a resurgence of manual testing communities focused on sharing techniques rather than just scanner configurations.
▶️ Related Video (84% Match):
🎯Let’s Practice For Free:
IT/Security Reporter URL:
Reported By: Haddad Al – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
