The site with research results noted that attackers can use the exploit to decrypt multiple types of sensitive data that is usually considered safe as it is encrypted with Wi-Fi encryption protocol.
KRACK exploits a four-way handshake that's normally executed when a user connects to a WPA2-protected Wi-Fi network. Handshake is executed to confirm that both a user and an access point bear the correct credentials. What KRACK does is it tricks the vulnerable client into reinstalling a key that is already in use, forcing the reset of packet numbers with valuable parameters. This way the cryptographic nonce is reused to allow the encryption to be bypassed.
The biggest threat KRACK poses is to large corporate and governmental Wi-Fi networks, especially if they accept connections from Linux and Android devices. The hackers should be within the attacked Wi-Fi range in order to carry out the attack, they probably wouldn't bother much with home Wi-Fi networks, plus there are easier ways to attack small home Wi-Fi, again, especially if they connect with Linux or Android devices.
Public Wi-Fi is an easier target for hackers, and public networks are not that well-protected to start with. To stay on the safe side, both public and office networks need to update their systems, and still a good idea would be to stay away from public networks until the issue is resolved.
If you feel like the access points you are using may be vulnerable, try to use wired connection for some time.
If you don't have a possibility to use a wired connection, make sure you are using HTTPS, STARTTLS, Secure Shell, or another reliable protocol.
Consider adding an extra layer of security with a VPN service. Make sure to choose a reputable VPN provider that you can trust though.
If you have a good cellular data package with enough speed, try using it when possible, especially instead of some public connections. While there can still be issues with this solution, especially on Android 6.0 and later, it is a better way to connect and stay protected from hackers.
Most of tech hardware and software vendors reacted to this breach fast and are providing patches for devices. Don't put off patching your phones, laptops, Wi-Fi base stations, and other gear. Patch asap if you have an iPhone, Mac, or Windows computer.
If you have an Android device — an update is soon to come. Some of the Wi-Fi access points also have patches available, so be sure to check for one. Many routers don't update automatically, so go ahead and see if yours can be updated right now.
KRACK ("Key Reinstallation Attacks") is a replay type of network attack that targets WPA2 protocol's flaws. This attack is equally dangerous for all major software platforms, including Microsoft Windows, macOS, iOS, Android, Linux, OpenBSD. The network security protocol that is considered safe can be bypassed, allowing a cybercriminal to intercept the data sent and received over the network.
The attack exploits the four-way handshake mechanism used for connecting to a WPA2-protected Wi-Fi network. The four-way handshake also negotiates a new encryption key for keeping all subsequent traffic secure.
By manipulating the handshake messages (the message 3 specifically) the attack tricks its victim into reinstalling an already-in-use key. By forcing nonce reuse in a specific manner, the encryption protocol can be attacked with subsequent forgery, replay, and decryption of packets.
There are some things you can do to avoid a KRACK attack: