25.3 WPA2 Handshake Capture and Offline Cracking
WPA2-PSK cracking cha marg asa: jevha ek device Wi-Fi la jodto, tevha 4-way handshake hoto. To handshake capture kela, ki attacker offline (Chapter 22 sarkha) wordlist ne passphrase try karto. Handshake madhe password nasto – password barobar asel tarach handshake match hoto.
# 1. capture on your network's channel (concept, your own Wi-Fi only)
sudo airodump-ng -c 6 --bssid AA:BB:CC:DD:EE:FF -w mycap wlan0mon
# 2. force one of your own devices to reconnect so the handshake is captured
sudo aireplay-ng --deauth 5 -a AA:BB:CC:DD:EE:FF wlan0mon
# 3. crack the captured handshake against a wordlist
aircrack-ng -w /usr/share/wordlists/rockyou.txt mycap-01.cap
The whole point: if your passphrase is a long, random one not in any wordlist, this attack fails. A short or common passphrase (12345678, password) is cracked quickly. This is the single most important Wi-Fi lesson.
Deauth affects real devices
aireplay-ng --deauth knocks devices off the network. Do it only to your own devices on your own Wi-Fi. Deauthing others is jamming/interception and illegal.
Ravindra Bagale's Tip
Students get scared when they hear "WPA2 can be cracked". But remember: WPA2 itself is not broken – a weak password is. With a random passphrase of 16+ characters, it won't be found even if you run through all of rockyou.txt. The security lies in the password; the protocol is good.
Ravindra Bagale's Tip – मराठी
"WPA2 crack होतो" ऐकून students घाबरतात. पण लक्षात ठेवा: WPA2 तोडला जात नाही – कमकुवत password तोडला जातो. 16+ characters चा random passphrase असेल तर rockyou.txt पूर्ण चालवली तरी तो सापडत नाही. सुरक्षा password मध्ये आहे, protocol चांगला आहे.
Ravindra Bagale's Tip – हिंदी
"WPA2 crack होता है" सुनकर students घबरा जाते हैं. पर याद रखो: WPA2 नहीं टूटता – कमज़ोर password टूटता है. 16+ characters का random passphrase हो तो पूरी rockyou.txt चलाने पर भी वह नहीं मिलता. सुरक्षा password में है, protocol अच्छा है.
Lab
On your own Wi-Fi, capture your own handshake (steps above) and try to crack it with rockyou.txt. First with a weak temporary passphrase (see it crack), then with a long random one (see it fail). Change the router back to the strong passphrase afterwards.
Extended teaching notes
Why this lesson matters
Use this lesson to strengthen systems you own: understand the risk, practise safely in a lab, then write and apply the fix.
Apply the fix across stacks
Same class of bug, same idea in every language.
Java / Spring Boot
Parameterise queries, encode output, CSRF tokens, limited Actuator, dependency scanning.
ASP.NET Core
EF Core / parameterised SQL, Razor encoding, HTTPS, Data Protection.
Node.js / Express
helmet, parameterised SQL, npm audit, avoid eval and shell concat.
Python / Django / Flask / FastAPI
ORM, autoescape, pip-audit, Bandit; never shell=True with user input.
PHP / Laravel
PDO/Eloquent, Blade escaping, composer audit.
Go / Ruby
database/sql placeholders / ActiveRecord; html/template / ERB escaping; govulncheck / Brakeman.
nginx / Apache / Tomcat
Hide versions, TLS, security headers, least-open ports.
MySQL / PostgreSQL / MongoDB / Redis
Private networks, auth on, least-privilege users, no 0.0.0.0/0.
AWS / Azure / GCP
Roles not long-lived keys, private data stores, cloud audit logs on.
Mini case study
Suppose we are on a purple-team exercise for an Indian mid-size company (sample data). Red notes a technique from this lesson against a lab clone. Blue must show the control that stops it, the log that would have fired, and the ticket that hardens production. That is the standard this course trains you for.
Defender's worksheet (do this today)
- Write the lesson title, date and the exact lab target you are allowed to use.
- List three owned systems (VMs, apps, or cloud accounts) where this lesson applies.
- Run one safe check from the lesson on a lab system only. Paste the command and output.
- Write a two-sentence fix you would give a teammate.
- Name one related public advisory (CERT-In, CISA, NVD, or a vendor bulletin) with its date.
Indian workplace (sample data)
Suppose we are a junior analyst at Infosys, TCS, Wipro or a fintech SOC in Bengaluru/Pune. Turn this lesson into one checklist item with an owner, a due date and a place to store evidence (ticket + screenshot).
Global practice
Compare your notes with OWASP, CIS Benchmarks, NIST CSF/IR guidance or a cloud Well-Architected security question. Write five lines on what overlaps.
Everyday analogy
Explain the risk and the fix to a family member without jargon. If they can repeat the warning, you understand it well enough to teach juniors.
Key terms
- Control: a safeguard (patch, config, process, detection).
- Finding: a weakness backed by evidence.
- Remediation: the fix plus how you verified it.
- Scope: systems you have written permission to touch.
- Least privilege: only the access the task needs.
- Defence in depth: several layers so one failure does not end the story.
Common mistakes
- Skipping written permission "just for a quick scan".
- Practising on hostel, office or public targets without authorisation.
- Collecting tool output without writing the fix.
- Copying attack steps onto production to "verify". Defenders verify with versions, configs and patches.
- Publishing screenshots that contain secrets, cookies or internal hostnames.
Recap
- Evidence, fix, owner, date.
- Own lab only.
- Fix > spectacle.