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1# SECUREAUTH LABS. Copyright 2020 SecureAuth Corporation. All rights reserved. 

2# 

3# This software is provided under under a slightly modified version 

4# of the Apache Software License. See the accompanying LICENSE file 

5# for more information. 

6# 

7# Description: 

8# Initial [MS-RCPH] Interface implementation 

9# 

10# Authors: 

11# Arseniy Sharoglazov <mohemiv@gmail.com> / Positive Technologies (https://www.ptsecurity.com/) 

12# 

13 

14import re 

15import binascii 

16from struct import unpack 

17 

18from impacket import uuid, ntlm, system_errors, nt_errors, LOG 

19from impacket.dcerpc.v5.rpcrt import DCERPCException 

20 

21from impacket.uuid import EMPTY_UUID 

22from impacket.http import HTTPClientSecurityProvider, AUTH_BASIC 

23from impacket.structure import Structure 

24from impacket.dcerpc.v5.rpcrt import MSRPCHeader, \ 

25 MSRPC_RTS, PFC_FIRST_FRAG, PFC_LAST_FRAG 

26 

27class RPCProxyClientException(DCERPCException): 

28 parser = re.compile(r'RPC Error: ([a-fA-F0-9]{1,8})') 

29 

30 def __init__(self, error_string=None, proxy_error=None): 

31 rpc_error_code = None 

32 

33 if proxy_error is not None: 

34 try: 

35 search = self.parser.search(proxy_error) 

36 rpc_error_code = int(search.group(1), 16) 

37 except: 

38 error_string += ': ' + proxy_error 

39 

40 DCERPCException.__init__(self, error_string, rpc_error_code) 

41 

42 def __str__(self): 

43 if self.error_code is not None: 

44 key = self.error_code 

45 if key in system_errors.ERROR_MESSAGES: 

46 error_msg_short = system_errors.ERROR_MESSAGES[key][0] 

47 return '%s, code: 0x%x - %s' % (self.error_string, self.error_code, error_msg_short) 

48 elif key in nt_errors.ERROR_MESSAGES: 

49 error_msg_short = nt_errors.ERROR_MESSAGES[key][0] 

50 return '%s, code: 0x%x - %s' % (self.error_string, self.error_code, error_msg_short) 

51 else: 

52 return '%s: unknown code: 0x%x' % (self.error_string, self.error_code) 

53 else: 

54 return self.error_string 

55 

56################################################################################ 

57# CONSTANTS 

58################################################################################ 

59 

60RPC_OVER_HTTP_v1 = 1 

61RPC_OVER_HTTP_v2 = 2 

62 

63# Errors which might need handling 

64 

65# RPCProxyClient internal errors 

66RPC_PROXY_REMOTE_NAME_NEEDED_ERR = 'Basic authentication in RPC proxy is used, ' \ 

67 'so coudn\'t obtain a target NetBIOS name from NTLMSSP to connect.' 

68 

69# Errors below contain a part of server responses 

70RPC_PROXY_INVALID_RPC_PORT_ERR = 'Invalid RPC Port' 

71RPC_PROXY_CONN_A1_0X6BA_ERR = 'RPC Proxy CONN/A1 request failed, code: 0x6ba' 

72RPC_PROXY_CONN_A1_404_ERR = 'CONN/A1 request failed: HTTP/1.1 404 Not Found' 

73RPC_PROXY_RPC_OUT_DATA_404_ERR = 'RPC_OUT_DATA channel: HTTP/1.1 404 Not Found' 

74RPC_PROXY_CONN_A1_401_ERR = 'CONN/A1 request failed: HTTP/1.1 401 Unauthorized' 

75RPC_PROXY_HTTP_IN_DATA_401_ERR = 'RPC_IN_DATA channel: HTTP/1.1 401 Unauthorized' 

76 

77 

78# 2.2.3.3 Forward Destinations 

79FDClient = 0x00000000 

80FDInProxy = 0x00000001 

81FDServer = 0x00000002 

82FDOutProxy = 0x00000003 

83 

84RTS_FLAG_NONE = 0x0000 

85RTS_FLAG_PING = 0x0001 

86RTS_FLAG_OTHER_CMD = 0x0002 

87RTS_FLAG_RECYCLE_CHANNEL = 0x0004 

88RTS_FLAG_IN_CHANNEL = 0x0008 

89RTS_FLAG_OUT_CHANNEL = 0x0010 

90RTS_FLAG_EOF = 0x0020 

91RTS_FLAG_ECHO = 0x0040 

92 

93# 2.2.3.5 RTS Commands 

94RTS_CMD_RECEIVE_WINDOW_SIZE = 0x00000000 

95RTS_CMD_FLOW_CONTROL_ACK = 0x00000001 

96RTS_CMD_CONNECTION_TIMEOUT = 0x00000002 

97RTS_CMD_COOKIE = 0x00000003 

98RTS_CMD_CHANNEL_LIFETIME = 0x00000004 

99RTS_CMD_CLIENT_KEEPALIVE = 0x00000005 

100RTS_CMD_VERSION = 0x00000006 

101RTS_CMD_EMPTY = 0x00000007 

102RTS_CMD_PADDING = 0x00000008 

103RTS_CMD_NEGATIVE_ANCE = 0x00000009 

104RTS_CMD_ANCE = 0x0000000A 

105RTS_CMD_CLIENT_ADDRESS = 0x0000000B 

106RTS_CMD_ASSOCIATION_GROUP_ID = 0x0000000C 

107RTS_CMD_DESTINATION = 0x0000000D 

108RTS_CMD_PING_TRAFFIC_SENT_NOTIFY = 0x0000000E 

109 

110################################################################################ 

111# STRUCTURES 

112################################################################################ 

113 

114# 2.2.3.1 RTS Cookie 

115class RTSCookie(Structure): 

116 structure = ( 

117 ('Cookie','16s=b"\\x00"*16'), 

118 ) 

119 

120# 2.2.3.2 Client Address 

121class EncodedClientAddress(Structure): 

122 structure = ( 

123 ('AddressType','<L=(0 if len(ClientAddress) == 4 else 1)'), 

124 ('_ClientAddress','_-ClientAddress','4 if AddressType == 0 else 16'), 

125 ('ClientAddress',':'), 

126 ('Padding','12s=b"\\x00"*12'), 

127 ) 

128 

129# 2.2.3.4 Flow Control Acknowledgment 

130class Ack(Structure): 

131 structure = ( 

132 ('BytesReceived','<L=0'), 

133 ('AvailableWindow','<L=0'), 

134 ('ChannelCookie',':',RTSCookie), 

135 ) 

136 

137# 2.2.3.5.1 ReceiveWindowSize 

138class ReceiveWindowSize(Structure): 

139 structure = ( 

140 ('CommandType','<L=0'), 

141 ('ReceiveWindowSize','<L=262144'), 

142 ) 

143 

144# 2.2.3.5.2 FlowControlAck 

145class FlowControlAck(Structure): 

146 structure = ( 

147 ('CommandType','<L=1'), 

148 ('Ack',':',Ack), 

149 ) 

150 

151# 2.2.3.5.3 ConnectionTimeout 

152class ConnectionTimeout(Structure): 

153 structure = ( 

154 ('CommandType','<L=2'), 

155 ('ConnectionTimeout','<L=120000'), 

156 ) 

157 

158# 2.2.3.5.4 Cookie 

159class Cookie(Structure): 

160 structure = ( 

161 ('CommandType','<L=3'), 

162 ('Cookie',':',RTSCookie), 

163 ) 

164 

165# 2.2.3.5.5 ChannelLifetime 

166class ChannelLifetime(Structure): 

167 structure = ( 

168 ('CommandType','<L=4'), 

169 ('ChannelLifetime','<L=1073741824'), 

170 ) 

171 

172# 2.2.3.5.6 ClientKeepalive 

173# 

174# By the spec, ClientKeepalive value can be 0 or in the inclusive 

175# range of 60,000 through 4,294,967,295. 

176# If it is 0, it MUST be interpreted as 300,000. 

177# 

178# But do not set it to 0, it will cause 0x6c0 rpc error. 

179class ClientKeepalive(Structure): 

180 structure = ( 

181 ('CommandType','<L=5'), 

182 ('ClientKeepalive','<L=300000'), 

183 ) 

184 

185# 2.2.3.5.7 Version 

186class Version(Structure): 

187 structure = ( 

188 ('CommandType','<L=6'), 

189 ('Version','<L=1'), 

190 ) 

191 

192# 2.2.3.5.8 Empty 

193class Empty(Structure): 

194 structure = ( 

195 ('CommandType','<L=7'), 

196 ) 

197 

198# 2.2.3.5.9 Padding 

199class Padding(Structure): 

200 structure = ( 

201 ('CommandType','<L=8'), 

202 ('ConformanceCount','<L=len(Padding)'), 

203 ('Padding','*ConformanceCount'), 

204 ) 

205 

206# 2.2.3.5.10 NegativeANCE 

207class NegativeANCE(Structure): 

208 structure = ( 

209 ('CommandType','<L=9'), 

210 ) 

211 

212# 2.2.3.5.11 ANCE 

213class ANCE(Structure): 

214 structure = ( 

215 ('CommandType','<L=0xA'), 

216 ) 

217 

218# 2.2.3.5.12 ClientAddress 

219class ClientAddress(Structure): 

220 structure = ( 

221 ('CommandType','<L=0xB'), 

222 ('ClientAddress',':',EncodedClientAddress), 

223 ) 

224 

225# 2.2.3.5.13 AssociationGroupId 

226class AssociationGroupId(Structure): 

227 structure = ( 

228 ('CommandType','<L=0xC'), 

229 ('AssociationGroupId',':',RTSCookie), 

230 ) 

231 

232# 2.2.3.5.14 Destination 

233class Destination(Structure): 

234 structure = ( 

235 ('CommandType','<L=0xD'), 

236 ('Destination','<L'), 

237 ) 

238 

239# 2.2.3.5.15 PingTrafficSentNotify 

240class PingTrafficSentNotify(Structure): 

241 structure = ( 

242 ('CommandType','<L=0xE'), 

243 ('PingTrafficSent','<L'), 

244 ) 

245 

246COMMANDS = { 

247 0x0: ReceiveWindowSize, 

248 0x1: FlowControlAck, 

249 0x2: ConnectionTimeout, 

250 0x3: Cookie, 

251 0x4: ChannelLifetime, 

252 0x5: ClientKeepalive, 

253 0x6: Version, 

254 0x7: Empty, 

255 0x8: Padding, 

256 0x9: NegativeANCE, 

257 0xA: ANCE, 

258 0xB: ClientAddress, 

259 0xC: AssociationGroupId, 

260 0xD: Destination, 

261 0xE: PingTrafficSentNotify, 

262} 

263 

264# 2.2.3.6.1 RTS PDU Header 

265# The RTS PDU Header has the same layout as the common header of 

266# the connection-oriented RPC PDU as specified in [C706] section 12.6.1, 

267# with a few additional requirements around the contents of the header fields. 

268class RTSHeader(MSRPCHeader): 

269 _SIZE = 20 

270 commonHdr = MSRPCHeader.commonHdr + ( 

271 ('Flags','<H=0'), # 16 

272 ('NumberOfCommands','<H=0'), # 18 

273 ) 

274 

275 def __init__(self, data=None, alignment=0): 

276 MSRPCHeader.__init__(self, data, alignment) 

277 self['type'] = MSRPC_RTS 

278 self['flags'] = PFC_FIRST_FRAG | PFC_LAST_FRAG 

279 self['auth_length'] = 0 

280 self['call_id'] = 0 

281 

282# 2.2.4.2 CONN/A1 RTS PDU 

283# 

284# The CONN/A1 RTS PDU MUST be sent from the client to the outbound proxy on the OUT channel to 

285# initiate the establishment of a virtual connection. 

286class CONN_A1_RTS_PDU(Structure): 

287 structure = ( 

288 ('Version',':',Version), 

289 ('VirtualConnectionCookie',':',Cookie), 

290 ('OutChannelCookie',':',Cookie), 

291 ('ReceiveWindowSize',':',ReceiveWindowSize), 

292 ) 

293 

294# 2.2.4.5 CONN/B1 RTS PDU 

295# 

296# The CONN/B1 RTS PDU MUST be sent from the client to the inbound proxy on the IN channel to 

297# initiate the establishment of a virtual connection. 

298class CONN_B1_RTS_PDU(Structure): 

299 structure = ( 

300 ('Version',':',Version), 

301 ('VirtualConnectionCookie',':',Cookie), 

302 ('INChannelCookie',':',Cookie), 

303 ('ChannelLifetime',':',ChannelLifetime), 

304 ('ClientKeepalive',':',ClientKeepalive), 

305 ('AssociationGroupId',':',AssociationGroupId), 

306 ) 

307 

308# 2.2.4.4 CONN/A3 RTS PDU 

309# 

310# The CONN/A3 RTS PDU MUST be sent from the outbound proxy to the client on the OUT channel to 

311# continue the establishment of the virtual connection. 

312class CONN_A3_RTS_PDU(Structure): 

313 structure = ( 

314 ('ConnectionTimeout',':',ConnectionTimeout), 

315 ) 

316 

317# 2.2.4.9 CONN/C2 RTS PDU 

318# 

319# The CONN/C2 RTS PDU MUST be sent from the outbound proxy to the client on the OUT channel to 

320# notify it that a virtual connection has been established. 

321class CONN_C2_RTS_PDU(Structure): 

322 structure = ( 

323 ('Version',':',Version), 

324 ('ReceiveWindowSize',':',ReceiveWindowSize), 

325 ('ConnectionTimeout',':',ConnectionTimeout), 

326 ) 

327 

328# 2.2.4.51 FlowControlAckWithDestination RTS PDU 

329class FlowControlAckWithDestination_RTS_PDU(Structure): 

330 structure = ( 

331 ('Destination',':',Destination), 

332 ('FlowControlAck',':',FlowControlAck), 

333 ) 

334 

335################################################################################ 

336# HELPERS 

337################################################################################ 

338def hCONN_A1(virtualConnectionCookie=EMPTY_UUID, outChannelCookie=EMPTY_UUID, receiveWindowSize=262144): 

339 conn_a1 = CONN_A1_RTS_PDU() 

340 conn_a1['Version'] = Version() 

341 conn_a1['VirtualConnectionCookie'] = Cookie() 

342 conn_a1['VirtualConnectionCookie']['Cookie'] = virtualConnectionCookie 

343 conn_a1['OutChannelCookie'] = Cookie() 

344 conn_a1['OutChannelCookie']['Cookie'] = outChannelCookie 

345 conn_a1['ReceiveWindowSize'] = ReceiveWindowSize() 

346 conn_a1['ReceiveWindowSize']['ReceiveWindowSize'] = receiveWindowSize 

347 

348 packet = RTSHeader() 

349 packet['Flags'] = RTS_FLAG_NONE 

350 packet['NumberOfCommands'] = len(conn_a1.structure) 

351 packet['pduData'] = conn_a1.getData() 

352 

353 return packet.getData() 

354 

355def hCONN_B1(virtualConnectionCookie=EMPTY_UUID, inChannelCookie=EMPTY_UUID, associationGroupId=EMPTY_UUID): 

356 conn_b1 = CONN_B1_RTS_PDU() 

357 conn_b1['Version'] = Version() 

358 conn_b1['VirtualConnectionCookie'] = Cookie() 

359 conn_b1['VirtualConnectionCookie']['Cookie'] = virtualConnectionCookie 

360 conn_b1['INChannelCookie'] = Cookie() 

361 conn_b1['INChannelCookie']['Cookie'] = inChannelCookie 

362 conn_b1['ChannelLifetime'] = ChannelLifetime() 

363 conn_b1['ClientKeepalive'] = ClientKeepalive() 

364 conn_b1['AssociationGroupId'] = AssociationGroupId() 

365 conn_b1['AssociationGroupId']['AssociationGroupId'] = RTSCookie() 

366 conn_b1['AssociationGroupId']['AssociationGroupId']['Cookie'] = associationGroupId 

367 

368 packet = RTSHeader() 

369 packet['Flags'] = RTS_FLAG_NONE 

370 packet['NumberOfCommands'] = len(conn_b1.structure) 

371 packet['pduData'] = conn_b1.getData() 

372 

373 return packet.getData() 

374 

375def hFlowControlAckWithDestination(destination, bytesReceived, availableWindow, channelCookie): 

376 rts_pdu = FlowControlAckWithDestination_RTS_PDU() 

377 rts_pdu['Destination'] = Destination() 

378 rts_pdu['Destination']['Destination'] = destination 

379 rts_pdu['FlowControlAck'] = FlowControlAck() 

380 rts_pdu['FlowControlAck']['Ack'] = Ack() 

381 rts_pdu['FlowControlAck']['Ack']['BytesReceived'] = bytesReceived 

382 rts_pdu['FlowControlAck']['Ack']['AvailableWindow'] = availableWindow 

383 

384 # Cookie of the channel for which the traffic received is being acknowledged 

385 rts_pdu['FlowControlAck']['Ack']['ChannelCookie'] = RTSCookie() 

386 rts_pdu['FlowControlAck']['Ack']['ChannelCookie']['Cookie'] = channelCookie 

387 

388 packet = RTSHeader() 

389 packet['Flags'] = RTS_FLAG_OTHER_CMD 

390 packet['NumberOfCommands'] = len(rts_pdu.structure) 

391 packet['pduData'] = rts_pdu.getData() 

392 

393 return packet.getData() 

394 

395def hPing(): 

396 packet = RTSHeader() 

397 packet['Flags'] = RTS_FLAG_PING 

398 

399 return packet.getData() 

400 

401################################################################################ 

402# CLASSES 

403################################################################################ 

404class RPCProxyClient(HTTPClientSecurityProvider): 

405 RECV_SIZE = 8192 

406 default_headers = {'User-Agent' : 'MSRPC', 

407 'Cache-Control': 'no-cache', 

408 'Connection' : 'Keep-Alive', 

409 'Expect' : '100-continue', 

410 'Accept' : 'application/rpc', 

411 'Pragma' : 'No-cache' 

412 } 

413 

414 def __init__(self, remoteName=None, dstport=593): 

415 HTTPClientSecurityProvider.__init__(self) 

416 self.__remoteName = remoteName 

417 self.__dstport = dstport 

418 

419 # Chosen auth type 

420 self.__auth_type = None 

421 

422 self.init_state() 

423 

424 def init_state(self): 

425 self.__channels = {} 

426 

427 self.__inChannelCookie = uuid.generate() 

428 self.__outChannelCookie = uuid.generate() 

429 self.__associationGroupId = uuid.generate() 

430 self.__virtualConnectionCookie = uuid.generate() 

431 

432 self.__serverConnectionTimeout = None 

433 self.__serverReceiveWindowSize = None 

434 self.__availableWindowAdvertised = 262144 # 256k 

435 self.__receiverAvailableWindow = self.__availableWindowAdvertised 

436 self.__bytesReceived = 0 

437 

438 self.__serverChunked = False 

439 self.__readBuffer = b'' 

440 self.__chunkLeft = 0 

441 

442 self.rts_ping_received = False 

443 

444 def set_proxy_credentials(self, username, password, domain='', lmhash='', nthash=''): 

445 LOG.error("DeprecationWarning: Call to deprecated method set_proxy_credentials (use set_credentials).") 

446 self.set_credentials(username, password, domain, lmhash, nthash) 

447 

448 def set_credentials(self, username, password, domain='', lmhash='', nthash='', aesKey='', TGT=None, TGS=None): 

449 HTTPClientSecurityProvider.set_credentials(self, username, password, 

450 domain, lmhash, nthash, aesKey, TGT, TGS) 

451 

452 def create_rpc_in_channel(self): 

453 headers = self.default_headers.copy() 

454 headers['Content-Length'] = '1073741824' 

455 

456 self.create_channel('RPC_IN_DATA', headers) 

457 

458 def create_rpc_out_channel(self): 

459 headers = self.default_headers.copy() 

460 headers['Content-Length'] = '76' 

461 

462 self.create_channel('RPC_OUT_DATA', headers) 

463 

464 def create_channel(self, method, headers): 

465 self.__channels[method] = HTTPClientSecurityProvider.connect(self, self._rpcProxyUrl.scheme, 

466 self._rpcProxyUrl.netloc) 

467 

468 auth_headers = HTTPClientSecurityProvider.get_auth_headers(self, self.__channels[method], 

469 method, self._rpcProxyUrl.path, headers)[0] 

470 

471 headers_final = {} 

472 headers_final.update(headers) 

473 headers_final.update(auth_headers) 

474 

475 self.__auth_type = HTTPClientSecurityProvider.get_auth_type(self) 

476 

477 # To connect to an RPC Server, we need to let the RPC Proxy know 

478 # where to connect. The target RPC Server name and its port are passed 

479 # in the query of the HTTP request. The target RPC Server must be the ncacn_http 

480 # service. 

481 # 

482 # The utilized format: /rpc/rpcproxy.dll?RemoteName:RemotePort 

483 # 

484 # For RDG servers, you can specify localhost:3388, but in other cases you cannot 

485 # use localhost as there will be no ACL for it. 

486 # 

487 # To know what RemoteName to use, we rely on Default ACL. It's specified 

488 # in the HKLM\SOFTWARE\Microsoft\Rpc\RpcProxy key: 

489 # 

490 # ValidPorts REG_SZ COMPANYSERVER04:593;COMPANYSERVER04:49152-65535 

491 # 

492 # In this way, we can at least connect to the endpoint mapper on port 593. 

493 # So, if the caller set remoteName to an empty string, we assume the target 

494 # is the RPC Proxy server itself, and get its NetBIOS name from the NTLMSSP. 

495 # 

496 # Interestingly, if the administrator renames the server after RPC Proxy installation 

497 # or joins the server to the domain after RPC Proxy installation, the ACL will remain 

498 # the original. So, sometimes the ValidPorts values have the format WIN-JCKEDQVDOQU, and 

499 # we are not able to use them. 

500 # 

501 # For Exchange servers, the value of the default ACL doesn't matter as they 

502 # allow connections by their own mechanisms: 

503 # - Exchange 2003 / 2007 / 2010 servers add their own ACL, which includes 

504 # NetBIOS names of all Exchange servers (and some other servers). 

505 # This ACL is regularly and automatically updated on each server. 

506 # Allowed ports: 6001-6004 

507 # 

508 # 6001 is used for MS-OXCRPC 

509 # 6002 is used for MS-OXABREF 

510 # 6003 is not used 

511 # 6004 is used for MS-OXNSPI 

512 # 

513 # Tests on Exchange 2010 show that MS-OXNSPI and MS-OXABREF are available 

514 # on both 6002 and 6004. 

515 # 

516 # - Exchange 2013 / 2016 / 2019 servers process RemoteName on their own 

517 # (via RpcProxyShim.dll), and the NetBIOS name format is supported only for 

518 # backward compatibility. 

519 # 

520 # ! Default ACL is never used, so there is no way to connect to the endpoint mapper! 

521 # 

522 # Allowed ports: 6001-6004 

523 # 

524 # 6001 is used for MS-OXCRPC 

525 # 6002 is used for MS-OXABREF 

526 # 6003 is not used 

527 # 6004 is used for MS-OXNSPI 

528 # 

529 # Tests show that all protocols are available on the 6001 / 6002 / 6004 ports via 

530 # RPC over HTTP v2, and the separation is only used for backward compatibility. 

531 # 

532 # The pure ncacn_http endpoint is available only on the 6001 TCP/IP port. 

533 # 

534 # RpcProxyShim.dll allows you to skip authentication on the RPC level to get 

535 # a faster connection, and it makes Exchange 2013 / 2016 / 2019 RPC over HTTP v2 

536 # endpoints vulnerable to NTLM-Relaying attacks. 

537 # 

538 # If the target is Exchange behind Microsoft TMG, you most likely need to specify 

539 # the remote name manually using the value from /autodiscover/autodiscover.xml. 

540 # Note that /autodiscover/autodiscover.xml might not be available with 

541 # a non-outlook User-Agent. 

542 # 

543 # There may be multiple RPC Proxy servers with different NetBIOS names on 

544 # a single external IP. We store the first one's NetBIOS name and use it for all 

545 # the following channels. 

546 # It's acceptable to assume all RPC Proxies have the same ACLs (true for Exchange). 

547 if not self.__remoteName and self.__auth_type == AUTH_BASIC: 

548 raise RPCProxyClientException(RPC_PROXY_REMOTE_NAME_NEEDED_ERR) 

549 

550 if not self.__remoteName: 

551 ntlmssp = self.get_ntlmssp_info() 

552 self.__remoteName = ntlmssp[ntlm.NTLMSSP_AV_HOSTNAME][1].decode('utf-16le') 

553 self._stringbinding.set_network_address(self.__remoteName) 

554 LOG.debug('StringBinding has been changed to %s' % self._stringbinding) 

555 

556 if not self._rpcProxyUrl.query: 

557 query = self.__remoteName + ':' + str(self.__dstport) 

558 self._rpcProxyUrl = self._rpcProxyUrl._replace(query=query) 

559 

560 path = self._rpcProxyUrl.path + '?' + self._rpcProxyUrl.query 

561 

562 self.__channels[method].request(method, path, headers=headers_final) 

563 self._read_100_continue(method) 

564 

565 def _read_100_continue(self, method): 

566 resp = self.__channels[method].sock.recv(self.RECV_SIZE) 

567 

568 while resp.find(b'\r\n\r\n') == -1: 

569 resp += self.__channels[method].sock.recv(self.RECV_SIZE) 

570 

571 # Continue responses can have multiple lines, for example: 

572 # 

573 # HTTP/1.1 100 Continue 

574 # Via: 1.1 FIREWALL1 

575 # 

576 # Don't expect the response to contain "100 Continue\r\n\r\n" 

577 if resp[9:23] != b'100 Continue\r\n': 

578 try: 

579 # The server (IIS) may return localized error messages in 

580 # the first line. Tests shown they are in UTF-8. 

581 resp = resp.split(b'\r\n')[0].decode("UTF-8", errors='replace') 

582 

583 raise RPCProxyClientException('RPC Proxy Client: %s authentication failed in %s channel' % 

584 (self.__auth_type, method), proxy_error=resp) 

585 except (IndexError, KeyError, AttributeError): 

586 raise RPCProxyClientException('RPC Proxy Client: %s authentication failed in %s channel' % 

587 (self.__auth_type, method)) 

588 

589 def create_tunnel(self): 

590 # 3.2.1.5.3.1 Connection Establishment 

591 packet = hCONN_A1(self.__virtualConnectionCookie, self.__outChannelCookie, self.__availableWindowAdvertised) 

592 self.get_socket_out().send(packet) 

593 

594 packet = hCONN_B1(self.__virtualConnectionCookie, self.__inChannelCookie, self.__associationGroupId) 

595 self.get_socket_in().send(packet) 

596 

597 resp = self.get_socket_out().recv(self.RECV_SIZE) 

598 

599 while resp.find(b'\r\n\r\n') == -1: 

600 resp += self.get_socket_out().recv(self.RECV_SIZE) 

601 

602 if resp[9:12] != b'200': 

603 try: 

604 # The server (IIS) may return localized error messages in 

605 # the first line. Tests shown they are in UTF-8. 

606 resp = resp.split(b'\r\n')[0].decode("UTF-8", errors='replace') 

607 

608 raise RPCProxyClientException('RPC Proxy CONN/A1 request failed', proxy_error=resp) 

609 except (IndexError, KeyError, AttributeError): 

610 raise RPCProxyClientException('RPC Proxy CONN/A1 request failed') 

611 

612 if b'Transfer-Encoding: chunked' in resp: 

613 self.__serverChunked = True 

614 

615 # If the body is here, let's send it to rpc_out_recv1() 

616 self.__readBuffer = resp[resp.find(b'\r\n\r\n') + 4:] 

617 

618 # Recieving and parsing CONN/A3 

619 conn_a3_rpc = self.rpc_out_read_pkt() 

620 conn_a3_pdu = RTSHeader(conn_a3_rpc)['pduData'] 

621 conn_a3 = CONN_A3_RTS_PDU(conn_a3_pdu) 

622 self.__serverConnectionTimeout = conn_a3['ConnectionTimeout']['ConnectionTimeout'] 

623 

624 # Recieving and parsing CONN/C2 

625 conn_c2_rpc = self.rpc_out_read_pkt() 

626 conn_c2_pdu = RTSHeader(conn_c2_rpc)['pduData'] 

627 conn_c2 = CONN_C2_RTS_PDU(conn_c2_pdu) 

628 self.__serverReceiveWindowSize = conn_c2['ReceiveWindowSize']['ReceiveWindowSize'] 

629 

630 def get_socket_in(self): 

631 return self.__channels['RPC_IN_DATA'].sock 

632 

633 def get_socket_out(self): 

634 return self.__channels['RPC_OUT_DATA'].sock 

635 

636 def close_rpc_in_channel(self): 

637 return self.__channels['RPC_IN_DATA'].close() 

638 

639 def close_rpc_out_channel(self): 

640 return self.__channels['RPC_OUT_DATA'].close() 

641 

642 def check_http_error(self, buffer): 

643 if buffer[:22] == b'HTTP/1.0 503 RPC Error': 

644 raise RPCProxyClientException('RPC Proxy request failed', proxy_error=buffer) 

645 

646 def rpc_out_recv1(self, amt=None): 

647 # Read with at most one underlying system call. 

648 # The function MUST return the maximum amt bytes. 

649 # 

650 # Strictly speaking, it may cause more than one read, 

651 # but that is ok, since that is to satisfy the chunked protocol. 

652 sock = self.get_socket_out() 

653 

654 if self.__serverChunked is False: 

655 if len(self.__readBuffer) > 0: 

656 buffer = self.__readBuffer 

657 self.__readBuffer = b'' 

658 else: 

659 # Let's read RECV_SIZE bytes and not amt bytes. 

660 # We would need to check the answer for HTTP errors, as 

661 # they can just appear in the middle of the stream. 

662 buffer = sock.recv(self.RECV_SIZE) 

663 

664 self.check_http_error(buffer) 

665 

666 if len(buffer) <= amt: 

667 return buffer 

668 

669 # We received more than we need 

670 self.__readBuffer = buffer[amt:] 

671 return buffer[:amt] 

672 

673 # Check if the previous chunk is still there 

674 if self.__chunkLeft > 0: 

675 # If the previous chunk is still there, 

676 # just give the caller what we already have 

677 if amt >= self.__chunkLeft: 

678 buffer = self.__readBuffer[:self.__chunkLeft] 

679 # We may have recieved a part of a new chunk 

680 self.__readBuffer = self.__readBuffer[self.__chunkLeft + 2:] 

681 self.__chunkLeft = 0 

682 

683 return buffer 

684 else: 

685 buffer = self.__readBuffer[:amt] 

686 self.__readBuffer = self.__readBuffer[amt:] 

687 self.__chunkLeft -= amt 

688 

689 return buffer 

690 

691 # Let's start to process a new chunk 

692 buffer = self.__readBuffer 

693 self.__readBuffer = b'' 

694 

695 self.check_http_error(buffer) 

696 

697 # Let's receive a chunk size field which ends with CRLF 

698 # For Microsoft TMG 2010 it can cause more than one read 

699 while buffer.find(b'\r\n') == -1: 

700 buffer += sock.recv(self.RECV_SIZE) 

701 self.check_http_error(buffer) 

702 

703 chunksize = int(buffer[:buffer.find(b'\r\n')], 16) 

704 buffer = buffer[buffer.find(b'\r\n') + 2:] 

705 

706 # Let's read at least our chunk including final CRLF 

707 while len(buffer) - 2 < chunksize: 

708 buffer += sock.recv(chunksize - len(buffer) + 2) 

709 

710 # We should not be using any information from 

711 # the TCP level to determine HTTP boundaries. 

712 # So, we may have received more than we need. 

713 if len(buffer) - 2 > chunksize: 

714 self.__readBuffer = buffer[chunksize + 2:] 

715 buffer = buffer[:chunksize + 2] 

716 

717 # Checking the amt 

718 if len(buffer) - 2 > amt: 

719 self.__chunkLeft = chunksize - amt 

720 # We may have recieved a part of a new chunk before, 

721 # so the concatenation is crucual 

722 self.__readBuffer = buffer[amt:] + self.__readBuffer 

723 

724 return buffer[:amt] 

725 else: 

726 # Removing CRLF 

727 return buffer[:-2] 

728 

729 def send(self, data, forceWriteAndx=0, forceRecv=0): 

730 # We don't use chunked encoding for IN channel as 

731 # Microsoft software is developed this way. 

732 # If you do this, it may fail. 

733 self.get_socket_in().send(data) 

734 

735 def rpc_out_read_pkt(self, handle_rts=False): 

736 while True: 

737 response_data = b'' 

738 

739 # Let's receive common RPC header and no more 

740 # 

741 # C706 

742 # 12.4 Common Fields 

743 # Header encodings differ between connectionless and connection-oriented PDUs. 

744 # However, certain fields use common sets of values with a consistent 

745 # interpretation across the two protocols. 

746 # 

747 # This MUST recv MSRPCHeader._SIZE bytes, and not MSRPCRespHeader._SIZE bytes! 

748 # 

749 while len(response_data) < MSRPCHeader._SIZE: 

750 response_data += self.rpc_out_recv1(MSRPCHeader._SIZE - len(response_data)) 

751 

752 response_header = MSRPCHeader(response_data) 

753 

754 # frag_len contains the full length of the packet for both 

755 # MSRPC and RTS 

756 frag_len = response_header['frag_len'] 

757 

758 # Receiving the full pkt and no more 

759 while len(response_data) < frag_len: 

760 response_data += self.rpc_out_recv1(frag_len - len(response_data)) 

761 

762 # We need to do the Flow Control procedures 

763 # 

764 # 3.2.1.1.4 

765 # This protocol specifies that only RPC PDUs are subject to the flow control abstract data 

766 # model. RTS PDUs and the HTTP request and response headers are not subject to flow control. 

767 if response_header['type'] != MSRPC_RTS: 

768 self.flow_control(frag_len) 

769 

770 if handle_rts is True and response_header['type'] == MSRPC_RTS: 

771 self.handle_out_of_sequence_rts(response_data) 

772 else: 

773 return response_data 

774 

775 def recv(self, forceRecv=0, count=0): 

776 return self.rpc_out_read_pkt(handle_rts=True) 

777 

778 def handle_out_of_sequence_rts(self, response_data): 

779 packet = RTSHeader(response_data) 

780 

781 #print("=========== RTS PKT ===========") 

782 #print("RAW: %s" % binascii.hexlify(response_data)) 

783 #packet.dump() 

784 # 

785 #pduData = packet['pduData'] 

786 #numberOfCommands = packet['NumberOfCommands'] 

787 # 

788 #server_cmds = [] 

789 #while numberOfCommands > 0: 

790 # numberOfCommands -= 1 

791 # 

792 # cmd_type = unpack('<L', pduData[:4])[0] 

793 # cmd = COMMANDS[cmd_type](pduData) 

794 # server_cmds.append(cmd) 

795 # pduData = pduData[len(cmd):] 

796 # 

797 #for cmd in server_cmds: 

798 # cmd.dump() 

799 #print("=========== / RTS PKT ===========") 

800 

801 # 2.2.4.49 Ping RTS PDU 

802 if packet['Flags'] == RTS_FLAG_PING: 

803 # 3.2.1.2.1 PingTimer 

804 # 

805 # If the SendingChannel is part of a Virtual Connection in the Outbound Proxy or Client roles, the 

806 # SendingChannel maintains a PingTimer that on expiration indicates a PING PDU must be sent to the 

807 # receiving channel. The PING PDU is sent to the receiving channel when no data has been sent within 

808 # half of the value of the KeepAliveInterval. 

809 

810 # As we do not do long-term connections with no data transfer, 

811 # it means something on the server-side is going wrong. 

812 self.rts_ping_received = True 

813 LOG.error("Ping RTS PDU packet received. Is the RPC Server alive?") 

814 

815 # Just in case it's a long operation, let's send PING PDU to IN Channel like in xfreerdp 

816 # It's better to send more than one PING packet as it only 20 bytes long 

817 packet = hPing() 

818 self.send(packet) 

819 self.send(packet) 

820 # 2.2.4.24 OUT_R1/A2 RTS PDU 

821 elif packet['Flags'] == RTS_FLAG_RECYCLE_CHANNEL: 

822 raise RPCProxyClientException("The server requested recycling of a virtual OUT channel, " \ 

823 "but this function is not supported!") 

824 # Ignore all other messages, most probably flow control acknowledgments 

825 else: 

826 pass 

827 

828 def flow_control(self, frag_len): 

829 self.__bytesReceived += frag_len 

830 self.__receiverAvailableWindow -= frag_len 

831 

832 if (self.__receiverAvailableWindow < self.__availableWindowAdvertised // 2): 

833 self.__receiverAvailableWindow = self.__availableWindowAdvertised 

834 packet = hFlowControlAckWithDestination(FDOutProxy, self.__bytesReceived, 

835 self.__availableWindowAdvertised, self.__outChannelCookie) 

836 self.send(packet) 

837 

838 def connect(self): 

839 self.create_rpc_in_channel() 

840 self.create_rpc_out_channel() 

841 self.create_tunnel() 

842 

843 def disconnect(self): 

844 self.close_rpc_in_channel() 

845 self.close_rpc_out_channel() 

846 self.init_state()