krack attack is a pseudonym for key reinstallation attacks. Krack attack uses a vulnerability in WPA2 (Wi-Fi Protected Access II ) handshake process. Wpa2 is used to protect communication of wireless devices. wpa2 has a mechanism that permits devices to join the network with a pre-shared password and a four-way handshake. The attack works against all modern protected Wi-Fi networks. The weaknesses are in the Wi-Fi standard itself, and not in individual products or implementations. Therefore, any correct implementation of WPA2 is likely affected.
According to Mathy Vanhoef, who discovered the flaw, threat actors can leverage the vulnerability to decrypt traffic, hijack connections, perform man-in-the-middle attacks, and eavesdrop on communication sent from a WPA2-enabled device.
Scripts to perform krack attack has released on GitHub.
You can find scripts here.