The attacks on WPA2
An attacker in radio range can try three things against WPA2: record a login and guess the password offline, fake "disconnect" frames, and run an evil twin, a fake access point with the same name. First see what your laptop sees, then each defence.
With WPA2-Personal, the laptop and access point run the 4-way handshake. The frames carry fresh random numbers (nonces) and check values (MICs) made from a key built from the shared password. All looks normal. But radio is shared: the attacker records every frame.
Later, on their own computer, the attacker tests guesses: each guess gives a key and a MIC to compare with the recording. The access point never sees these tries, so it cannot slow or block them. A match reveals the password.
The laptop receives a deauthentication frame, a "you are disconnected" notice. Its sender address says access point, but the attacker sent it. Without protection, which WPA2 left optional, management frames carry no proof of sender, so the laptop believes it and drops off.
Now the laptop sees two networks called "OfficeNet". Many devices pick the stronger signal, and the twin is closer. With WPA2-Personal, anyone who knows the shared password can run a twin that passes the handshake. The laptop cannot tell which is real.
WPA3-Personal: SAE
WPA3-Personal checks the password with SAE (Simultaneous Authentication of Equals, also called Dragonfly). Both sides turn the password into a secret point on an elliptic curve, add fresh random numbers, and swap "commit" messages that reveal nothing to test guesses against.
Each side mixes its own random secret with the other's commit and gets the same key, the PMK, which is never sent. "Confirm" messages prove both got it. Then the usual 4-way handshake makes the session keys.
The attacker recorded every frame. With WPA2, they could test millions of password guesses against that recording on their own computer. SAE leaves nothing to test against: each guess needs a live login attempt with the access point, one guess per try.
SAE also gives forward secrecy. The random secrets are thrown away after each login, so someone who learns the password later still cannot unlock traffic they recorded today. With WPA2, the password plus a recorded handshake was enough.
Protected management frames
WPA3 makes Protected Management Frames (PMF) mandatory. A real disconnect notice now carries a check made with a key only the access point and laptop share. When the forged frame arrives again, it has no valid check, so the laptop ignores it.
Enterprise: 802.1X
Offices use WPA2- or WPA3-Enterprise, built on 802.1X. There is no shared password: each person has their own account. The access point only passes messages along. It carries the laptop's EAP login to a RADIUS server, which decides.
Before sending any password, the laptop makes the RADIUS server prove who it is. The server sends its certificate and starts a TLS tunnel. The laptop checks the server name and that a CA it was set up to trust signed it.
The evil twin copies the name "OfficeNet", and the laptop may even join it. But it cannot show a valid certificate for radius.example.com: it lacks the real server's private key. The check fails, and the laptop stops before sending its password.
On success, RADIUS sends the access point a fresh key for this login only; the laptop worked out the same key itself. The 4-way handshake turns it into session keys. Other users cannot unlock this traffic, and one account can be blocked alone.
The frames, field by field
;; step 1/14 · the-attacks · local ;; at attacker + your laptop + access point three attacks on WPA2, seen from the defending laptop: 1 a recorded 4-way handshake, then password guesses tested offline 2 forged deauthentication frames that claim to come from the AP 3 an evil twin: a fake AP that copies the name "OfficeNet" the defences that beat them, in order: 1 SAE (WPA3-Personal) 2 Protected Management Frames 3 802.1X + certificate check
WPA3 "transition mode" lets old WPA2 devices join the same network. Those WPA2 links get none of SAE's protection, so turn it off once every device supports WPA3. The evil-twin defence only works when each device is set to validate the server certificate and its name. A profile that skips the check, or asks users to accept any certificate, reopens the attack.