KRACK
Definition
Key Reinstallation Attack, CVE-2017-13077, disclosed by Mathy Vanhoef in 2017. By replaying message 3 of the 4-way handshake, the client is forced to reinstall an already-in-use key, resetting the packet number and exposing traffic to keystream reuse.
- Full name
- Key Reinstallation Attack
- CVE
- CVE-2017-13077
- Disclosed by
- Mathy Vanhoef, 2017
- Target
- 4-way handshake, message 3 replay
- Effect
- Forces key reinstallation, resets packet number
Common questions
What can an attacker actually do once KRACK succeeds?+
Resetting the nonce and packet counter allows keystream reuse, which can let an attacker decrypt some captured packets and, depending on the cipher suite in use, inject or replay traffic.
Does KRACK mean WPA2 encryption itself was broken?+
No, the underlying encryption algorithm was not broken. The flaw was in the handshake protocol's state handling, and it was fixed with software patches to clients and access points rather than a new cipher.
Related terms
- 4-Way Handshake
- The WPA/WPA2 key-establishment exchange between client and AP. Captured frames let an offline dictionary attack recover a weak PSK. WPA3 replaces this...
- BSSID / ESSID
- BSSID is the MAC address of the access point (or virtual AP). ESSID is the human-readable network name broadcast in beacons. Multiple...
- Evil Twin
- A rogue AP broadcasting the same ESSID as a legitimate network at a stronger signal, so clients with cached profiles auto-associate. Often...
- IMSI Catcher
- A rogue base station (commercial: Stingray, Hailstorm, KingFisher; research: USRP plus srsRAN or YateBTS) that impersonates a cellular cell, forces nearby phones...
- PMKID Attack
- A 2018 technique by Jens Steube (hashcat author) that derives the Pairwise Master Key Identifier from a single EAPOL frame the AP...