mysql-dump-hashes.nse uses password field instead of authentication_string for MySQL 5.7+ versions

[maksyche]

Describe the bug
MySQL changed password field name to authentication_string in the 5.7 version, but mysql-dump-hashes.nse script still uses the old field name which causes this problem:

NSOCK INFO [0.7460s] nsock_trace_handler_callback(): Callback: READ SUCCESS for EID 50 [*.*.*.*:3306] (54 bytes): 2......#42S22Unknown column 'password' in 'field list'

To Reproduce
Just run nmap with mysql-dump-hashes script against MySQL 5.7+ version. For example: nmap -p 3306 <ip> --script mysql-dump-hashes --script-args='username=root,password=secret' --script-trace

Expected behavior
Script should print hashes for the MySQL 5.7+ version.

Version info (please complete the following information):

• OS: Kali Linux 2020.4
• Nmap version 7.91 ( https://nmap.org )
  Platform: x86_64-pc-linux-gnu
  Compiled with: liblua-5.3.3 openssl-1.1.1g libssh2-1.8.0 libz-1.2.11 libpcre-8.39 nmap-libpcap-1.7.3 nmap-libdnet-1.12 ipv6
  Compiled without:
  Available nsock engines: epoll poll select

Additional context
I see the hardcoded password field in the source code: https://github.com/nmap/nmap/blob/master/scripts/mysql-dump-hashes.nse. Line 87 "SELECT DISTINCT CONCAT(user, ':', password) FROM mysql.user WHERE password <> ''"

[Herostere]

Hello.

You are right.
There must be a verification for the MySQL version, and if the version is > 5.6 the script should call:
"SELECT DISTINCT CONCAT(user, ':', authentication_string) FROM mysql.user WHERE authentication_string <> ''"

Here is the updated code:

local mysql = require "mysql"
local nmap = require "nmap"
local shortport = require "shortport"
local stdnse = require "stdnse"

description = [[
Dumps the password hashes from an MySQL server in a format suitable for
cracking by tools such as John the Ripper.  Appropriate DB privileges (root) are required.

The <code>username</code> and <code>password</code> arguments take precedence
over credentials discovered by the mysql-brute and mysql-empty-password
scripts.
]]

---
-- @usage
-- nmap -p 3306 <ip> --script mysql-dump-hashes --script-args='username=root,password=secret'
--
-- @output
-- PORT     STATE SERVICE
-- 3306/tcp open  mysql
-- | mysql-dump-hashes:
-- |   root:*9B500343BC52E2911172EB52AE5CF4847604C6E5
-- |   debian-sys-maint:*92357EE43977D9228AC9C0D60BB4B4479BD7A337
-- |_  toor:*14E65567ABDB5135D0CFD9A70B3032C179A49EE7
--
-- @args username the username to use to connect to the server
-- @args password the password to use to connect to the server
--

author = "Patrik Karlsson"
license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
categories = {"auth", "discovery", "safe"}


dependencies = {"mysql-empty-password", "mysql-brute"}

portrule = shortport.port_or_service(3306, "mysql")

local arg_username = stdnse.get_script_args(SCRIPT_NAME .. ".username")
local arg_password = stdnse.get_script_args(SCRIPT_NAME .. ".password") or ""

local function fail(err) return stdnse.format_output(false, err) end

local function getCredentials()
  -- first, let's see if the script has any credentials as arguments?
  if ( arg_username ) then
    return { [arg_username] = arg_password }
  -- next, let's see if mysql-brute or mysql-empty-password brought us anything
  elseif nmap.registry.mysqlusers then
    -- do we have root credentials?
    if nmap.registry.mysqlusers['root'] then
      return { ['root'] = nmap.registry.mysqlusers['root'] }
    else
      -- we didn't have root, so let's make sure we loop over them all
      return nmap.registry.mysqlusers
    end
  -- last, no dice, we don't have any credentials at all
  end
end

local function mysqlLogin(socket, username, password)
  local status, response = mysql.receiveGreeting( socket )
  if ( not(status) ) then
    return response
  end
  -- Herostere
  return mysql.loginRequest( socket, { authversion = "post41", charset = response.charset }, username, password, response.salt ), response.version
  -- return mysql.loginRequest( socket, { authversion = "post41", charset = response.charset }, username, password, response.salt )
  --
end


action = function(host, port)
  local creds = getCredentials()
  if ( not(creds) ) then
    stdnse.debug2("No credentials were supplied, aborting ...")
    return
  end

  local result = {}
  for username, password in pairs(creds) do
    local socket = nmap.new_socket()
    if ( not(socket:connect(host, port)) ) then
      return fail("Failed to connect to server")
    end

    -- Herostere
    local status,version = mysqlLogin(socket, username, password)
    -- local status, response= mysqlLogin(socket, username, password)
    --
    if ( status ) then
      -- Herostere
      local versionNumber = tonumber(version:sub(1,3))
      local query = ''
      if versionNumber > 5.6 then
	query = "SELECT DISTINCT CONCAT(user, ':', authentication_string) FROM mysql.user WHERE authentication_string <> ''"
      else
        query = "SELECT DISTINCT CONCAT(user, ':', password) FROM mysql.user WHERE password <> ''" 
      end
      -- local query = "SELECT DISTINCT CONCAT(user, ':', password) FROM mysql.user WHERE password <> ''" 
      -- 
      local status, rows = mysql.sqlQuery( socket, query )
      socket:close()
      if ( status ) then
        result = mysql.formatResultset(rows, { noheaders = true })
        break
      end
    else
      socket:close()
    end
  end

  if ( result ) then
    return stdnse.format_output(true, result)
  end
end

No big changes as you can see. I marked the zone I edited for you to be able to find it quickly.
This is the first time I've read code in Lua. My solution may not be the most elegant.