Wi-Fi & 802.11 · Study deck

Wi-Fi Security: Provisioning and Recovery Evidence

A device that cannot rotate a key will fail its next security review.

Radio Remi is your guide for this deck.

wifi-securityprovisioning-reviewcredential-management
Radio Remi, the module guide, in a scene from this chapter.
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After studying this chapter

Learning objectives

You will be able to:

  • Plan credential recovery, rotation, and device removal.
  • Review provisioning evidence for shared-key and per-device risks.
  • Explain: For home and IoT networks the dominant schemes are WPA2-Personal and its successor WPA3-Personal.
  • Explain: That distinction is necessary before judging what a captured handshake reveals and why passphrase quality still matters.
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Major section

Authenticate, Then Derive Keys

For home and IoT networks the dominant schemes are WPA2-Personal and its successor WPA3-Personal.

  • Both start from a shared password, but they turn it into keys very differently — and that difference decides how resistant the network is to attack.
  • Typing a passphrase into a sensor with no keyboard is impossible, so the industry built dedicated onboarding methods.
  • The review should keep those jobs separate.
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Major section

The WPA2 Four-Way Handshake and Its Weakness

That distinction is necessary before judging what a captured handshake reveals and why passphrase quality still matters.

  • The passphrase itself is not transmitted; both peers derive the PTK from the PMK, nonces, and addresses, while MICs prove possession.
  • This offline-guessing exposure is exactly what WPA3 was designed to close.
  • Retransmission itself is correct.
Use the handshake diagram to separate proof of session-key establishment from the broader fleet questions: password strength, shared-secret exposure, rotation, segmentation, and device removal.
Use the handshake diagram to separate proof of session-key establishment from the broader fleet questions: password strength, shared-secret exposure, rotation, segmentation, and device removal.
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Major section

The WPA2 Four-Way Handshake and Its Weakness (continued)

A capture therefore supplies material for offline guesses: an attacker can derive candidate keys and test the MIC without contacting the AP.

  • This connects session establishment to the chapter's fleet controls for passphrase entropy, rotation, segmentation, and device removal.
  • In a defensive review, the point is not to reproduce an attack.
  • The four-way handshake must tolerate a lost final acknowledgement.
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Major section

The WPA2 Four-Way Handshake and Its Weakness (continued)

If message 4 does not reach the AP, the AP retransmits message 3.

  • The failure appears when a client treats a valid retransmission as a command to install the same pairwise key again and resets state that must never move backwards.
  • The repair is a state-machine invariant: after a key is installed, a retransmitted message may be acknowledged but must not reinstall that key or reset its nonce/replay counters.
  • WPA2 devices with patched supplicants can be safe from this flaw; migrating protocol labels without updating vulnerable implementations is not a fix.
WPA2 KRACK state and WPA3 mechanism map.
WPA2 KRACK state and WPA3 mechanism map.
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Major section

WPA3-SAE, PMF, and DPP Onboarding

A passively captured SAE exchange does not permit the straightforward offline dictionary test used against a captured WPA2-PSK handshake; an active guess needs an exchange with the network.

  • WPA3 additionally requires Protected Management Frames (802.11w), which authenticate deauthentication and disassociation frames after protection is established.
  • No keyboard is needed.
  • After association, PMF protects applicable management frames, while setup and radio denial-of-service risks still need review.

Why it matters

PMF reduces forged-frame attacks but cannot prevent all radio denial of service.

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Major section

WPA3-SAE, PMF, and DPP Onboarding (continued)

During setup the installer scans it with the vendor app (the configurator); DPP uses the encoded public key to establish a secure channel and provision the sensor onto the WPA3 network.

  • The under-the-hood acceptance evidence is the negotiated behavior, not the label on the box.
  • Also record what invalidates the approval: AP profile change, firmware change, installer app change, QR label process change, credential rotation, ownership transfer, or service-path change.
  • PMF reduces forged-frame attacks but cannot prevent all radio denial of service.
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Major section

Figure Review: Migration and Handshake State

Legacy Wi-Fi security is easiest to reject when its failure mechanisms are traced through the packet-protection sequence rather than reduced to an age label.

  • Modern protocol review must also distinguish a sound key exchange from an unsafe implementation state transition.
WEP failure and TKIP migration sequence.
WEP failure and TKIP migration sequence.
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Deck summary

Key takeaways

For home and IoT networks the dominant schemes are WPA2-Personal and its successor WPA3-Personal.

  • That distinction is necessary before judging what a captured handshake reveals and why passphrase quality still matters.
  • A capture therefore supplies material for offline guesses: an attacker can derive candidate keys and test the MIC without contacting the AP.
  • If message 4 does not reach the AP, the AP retransmits message 3.
  • A passively captured SAE exchange does not permit the straightforward offline dictionary test used against a captured WPA2-PSK handshake; an active guess needs an exchange with the network.
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Retrieval practice

Recall check 1 of 5

Radio Remi says: answer from memory, then check your reasoning.

Q1A facility rotates its Wi-Fi credential, and several offline sensors cannot rejoin when they wake. What recovery evidence is needed before approving the rollout?

AA tested reset or reprovisioning path, named support owner, and evidence of how failed devices regain service.
BAn installer handover record naming the new credential, its activation date, and the devices assigned to receive it.
CA promise to keep the old credential forever for any device that fails.
DA dashboard that hides join failures until all devices reconnect.
Show answer

Answer: A Credential rotation needs a tested reprovisioning path, failed-join monitoring, support ownership, and a bounded recovery decision.

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Retrieval practice

Recall check 2 of 5

Radio Remi says: answer from memory, then check your reasoning.

Q2A headless device opens a temporary setup path for Wi-Fi onboarding. What evidence should the reviewer request before accepting it?

AA happy-path setup screenshot plus the installer app name, device model, and no failure evidence.
BA support note saying setup mode is temporary and usually closes after install.
CEntry/exit rules, possession proof, credential handling, timeout, failures, reset, support, and retest triggers.
DThe SSID, phone OS version, and QR-code label photo used during one successful setup.
Show answer

Answer: C Provisioning is part of the security boundary and must be reviewed as a lifecycle workflow.

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Retrieval practice

Recall check 3 of 5

Radio Remi says: answer from memory, then check your reasoning.

Q3What two distinct problems does Wi-Fi security-and-provisioning address for an IoT device?

AAgreeing link keys and provisioning credentials without a screen.
BChoosing a channel and setting transmit power on the same link.
CAssigning IP addresses and DNS names for the same device.
DSelecting between 2.4 and 5 GHz radio bands for the link.
Show answer

Answer: A Key agreement protects traffic; provisioning is the separate challenge of onboarding a device with no keyboard.

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Retrieval practice

Recall check 4 of 5

Radio Remi says: answer from memory, then check your reasoning.

Q4Why is a captured WPA2-Personal four-way handshake a security risk?

AIt exposes the plaintext Wi-Fi passphrase directly inside the captured frames.
BIt gives an attacker offline material for passphrase guesses by deriving keys and checking the MIC.
CIt lets the attacker change the AP channel and force clients onto weaker RF settings.
DIt matters only for open networks, because password-protected WPA2 has no handshake.
Show answer

Answer: B WPA2's handshake is vulnerable to offline dictionary attack once captured, which is why passphrase strength matters.

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Retrieval practice

Recall check 5 of 5

Radio Remi says: answer from memory, then check your reasoning.

Q5How does WPA3's SAE handshake defeat the offline dictionary attack that threatens WPA2?

ASAE automatically lengthens weak passphrases before the AP accepts a client.
BSAE sends the password encrypted, so the passphrase can be reused safely.
CSAE removes the four-way handshake and uses only protected management frames.
DSAE makes each password guess require a fresh online exchange and adds forward secrecy.
Show answer

Answer: D SAE (Dragonfly) removes any offline-verifiable value, throttling guesses to online attempts and protecting past sessions.

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Print reference

Answers 1 of 2

Answer key.

  1. A · Credential rotation needs a tested reprovisioning path, failed-join monitoring, support ownership, and a bounded recovery decision.
  2. C · Provisioning is part of the security boundary and must be reviewed as a lifecycle workflow.
  3. A · Key agreement protects traffic; provisioning is the separate challenge of onboarding a device with no keyboard.
  4. B · WPA2's handshake is vulnerable to offline dictionary attack once captured, which is why passphrase strength matters.
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Print reference

Answers 2 of 2

Answer key.

  1. D · SAE (Dragonfly) removes any offline-verifiable value, throttling guesses to online attempts and protecting past sessions.
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