Encryption Vulnerabilities and WPS Exploitation
Here the exam checks whether you can pick the right attack for the encryption in front of you and explain why it works - WEP keystream reuse, WPA/WPA2-PSK offline cracking, or the WPS PIN's structural weakness.
WEP
WEP concatenates a 24-bit IV with the key, runs RC4, then appends a CRC32 ICV. With a small IV space and no per-packet rekeying, keystreams repeat. FMS and KoreK exploited weak IVs; the PTW attack needs roughly 40,000 packets and works best against ARP traffic. aireplay-ng -3 -b <BSSID> -h <your MAC> wlan0mon replays ARP to generate packets; aircrack-ng -b <BSSID> cap.cap recovers the key (-1 for 40-bit).
WPA/WPA2-PSK
Purely offline: capture a handshake or a PMKID, then run a wordlist. aircrack-ng -w rockyou.txt -e SSID cap.cap, or convert with hcxtools and use hashcat -m 22000. If the passphrase is not in the wordlist, no amount of compute helps.
WPS
The 8-digit PIN is validated in halves plus a checksum, collapsing the space to about 11,000 guesses. wash -i wlan0mon lists WPS version, lock status and vendor. reaver -i wlan0mon -b <BSSID> -vv brute-forces online; -K 1 runs the Pixie Dust offline attack against weak nonces, common on Ralink and Realtek chipsets, and can finish in seconds.
Worked example
wash reports WPS 1.0 with Locked: No. Reasoning: run Pixie Dust first, because it consumes no PIN attempts and cannot trigger a lockout; if reaver returns "WPS pin not found", the nonces are not weak, and online brute force is only viable if no lockout policy is enforced.
Traps
- Pointing aircrack-ng at WPA3/SAE: there is no PSK handshake to crack.
- Forgetting
airmon-ng check kill, so wpa_supplicant interferes with injection and capture. - Running online WPS brute force against an AP already in a locked state.
- Mixing up 40-bit and 104-bit WEP key lengths when reading the recovered key.