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@vanhoefm vanhoefm/findmac.py
Last active Jun 24, 2020

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#!/usr/bin/python
from scapy.all import *
import random
# number of times to inject probe for one bit (combat packet loss)
ATTEMPTS_PER_BIT = 3
# time to wait for ACK in seconds
SNIFFTIME = 0.1
def randmac():
mac = [0] * 6
for i in xrange(6):
mac[i] = random.randint(0, 256)
return ":".join([format(byte, '02x') for byte in mac])
def parsemac(macstr):
parts = macstr.replace("-", ":").split(":")
if len(parts) != 6:
raise ValueError("MAC does not consist of 6 parts (separated by : or -)")
return [int(byte, 16) for byte in parts]
def is_ack(p):
return Dot11 in p and p.type == 1 and p.subtype == 13
def find_fixed_bits(s, mac):
# eventually contains the real MAC address
orgmac = [0] * 6
# random MAC address, used as sender, to which the target will send an ACK
srcmac = randmac()
# for all the bits - FIXME: Don't consider H.O. bit of first MAC byte
for i in range(6):
for bit in range(8):
# flip the bit at current position
currbit = mac[i] & (1 << bit)
mac[i] ^= (1 << bit)
# convert modified mac to string
strmac = ":".join([format(byte, '02x') for byte in mac])
print "Probing", strmac, "...",
replied = False
for attempt in range(ATTEMPTS_PER_BIT):
# inject data packet to modified MAC address
packet = Dot11(type="Data", subtype=4, FCfield="from-DS",
addr1=strmac, addr2=srcmac, addr3=strmac)
s.send(RadioTap()/packet)
# Sniff air for ACK to modified MAC
l = sniff(lfilter=lambda p: is_ack(p) and p.addr1 == srcmac, count=1,
timeout=SNIFFTIME, opened_socket=s)
# We we got an ACK, don't need to try again
if len(l) == 1:
replied = True
break
print replied
# If client replied, original bit is different from the one currently set,
# otherwise it's equal to original bit.
if replied:
orgmac[i] |= (~currbit) & (1 << bit)
else:
orgmac[i] |= currbit
# flip bit back to original value
mac[i] ^= (1 << bit)
# Done, return original MAC
return orgmac
if __name__ == "__main__":
if len(sys.argv) != 3:
print "Usage:", sys.argv[0], "interface macaddr"
quit(1)
try:
mac = parsemac(sys.argv[2])
conf.iface = sys.argv[1]
random.seed()
# Open up read/write socket so we don't miss the ACK
L2socket = conf.L2socket
s = L2socket(type=ETH_P_ALL, iface=conf.iface)
# Now find the MAC
orgmac = find_fixed_bits(s, mac)
s.close()
print "\nReal MAC address:", ":".join(format(byte, "02x") for byte in orgmac), "\n"
except ValueError, e:
print "Invalid MAC address:", e
except socket.error, e:
print "Error with provided interface:", e
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