KRACK (Key Reinstallation AttaCK)

KRACK (Key Reinstallation AttaCK)

Brief, Impact, Recommendation & References

Introduction

A severe flaw in most secured WPA2 Protocol of WIFI Standard, successful exploitation of which allow an attacker in range of WIFI enabled devices or network to read data in transit (i.e. such as username, password and credit card details etc.) and is potentially at risk of leakage and can modify depends on WIFI implementations. 

The Weakness is in the WI-FI standard itself and thus even secured implemented WPA2 WIFI network can also be prone to attack.

KRACK (Key Reinstallation AttaCK) exploit a weakness in Four-way handshake process between a user’s device trying to connect and a WI-FI Network. It allows an attacker unauthorized access to the network without knowing the password and the possibility of performing Man-In-The-Middle Attack to sniff or modifying the data.

KRACK Attack: Example against 4-way handshake  

In a key reinstallation attack, the adversary tricks a victim into reinstalling an already-in-use key. A client initiate a connection and join a network, execute the 4-way handshake to generate encryption key. The same encryption key will install after receiving message 3 of 4-way handshake. Once the key is installed, the same encryption key is used to encrypt the normal data using the encryption protocol. In case of message drop or lost, Access Point will retransmit the message 3 if it did not receive an appropriate acknowledgement response and client receive message 3 multiple times and will reinstall the same encryption key and thereby reset the transmit packet number (nonce) and receive replay counter used by encryption protocol.

An attacker can force these nonce resets by collecting and replaying retransmissions of message 3 of 4-way handshake. By forcing nonce reuse in this manner, the encryption protocol can be attacked, e.g., packets can be replayed, decrypted, and/or forged.

 

Impact: 

1. Data in transit can be read by the attacker.
2. Data in transit may be modified if WIFI implemented with WPA-TKIP or GCMP protocols and more can be done.

Ways to protect yourself 

1. Update your devices, operating systems and perimeter devices with latest update and configure them to automatic updates with latest patches
2. Keep all your IT devices up to date and upgraded with latest versions.
3. Use VPN, will encrypt all your internet traffic and could protect you from this types of attack.
4. Always use SLL over your application like Secured HTTP, FTP and more.
5. Use LAN connection instead of WIFI for your critical business functions till patch is available for your AP/Device/System.

Affected Vendor Products:

Refer link: http://www.kb.cert.org/vuls/byvendor?searchview&Query=FIELD+Reference=228519&SearchOrder=4

 

Vendors released KRACK Patched:

Refer link: https://www.fixkrack.com/