Hi. I just got a site to manage, but am not too sure about the code the previous guy wrote. I'm pasting the login procedure below, could you have a look and tell me if there are any security vulnerabilities? At first glance, it seems like one could get in through SQL injection or manipulating cookies and the ?m= parameter.

define ( 'CURRENT_TIME', time ()); / / Current time. 
define ( 'ONLINE_TIME_MIN', (CURRENT_TIME - BOTNET_TIMEOUT)); / / Minimum time for the status of "Online". 
define ( 'DEFAULT_LANGUAGE', 'en'); / / Default language. 
define ( 'THEME_PATH', 'theme'); / / folder for the theme. 

/ / HTTP requests. 
define ( 'QUERY_SCRIPT', basename ($ _SERVER [ 'PHP_SELF'])); 
define ( 'QUERY_SCRIPT_HTML', QUERY_SCRIPT); 
define ( 'QUERY_VAR_MODULE', 'm'); / / variable contains the current module. 
define ( 'QUERY_STRING_BLANK', QUERY_SCRIPT. '? m ='); / / An empty query string. 
define ( 'QUERY_STRING_BLANK_HTML', QUERY_SCRIPT_HTML. '? m ='); / / Empty query string in HTML. 
define ( 'CP_HTTP_ROOT', str_replace ( '\ \', '/', (! empty ($ _SERVER [ 'SCRIPT_NAME'])? dirname ($ _SERVER [ 'SCRIPT_NAME']):'/'))); / / root of CP. 

/ / The session cookie. 
define ( 'COOKIE_USER', 'p'); / / Username in the cookies. 
define ( 'COOKIE_PASS', 'u'); / / user password in the cookies. 
define ( 'COOKIE_LIVETIME', CURRENT_TIME + 2592000) / / Lifetime cookies. 
define ( 'COOKIE_SESSION', 'ref'); / / variable to store the session. 
define ( 'SESSION_LIVETIME', CURRENT_TIME + 1300) / / Lifetime of the session. 

////////////////////////////////////////////////// ///////////////////////////// 
/ / Initialize. 
////////////////////////////////////////////////// ///////////////////////////// 

/ / Connect to the database. 
if (! ConnectToDB ()) die (mysql_error_ex ()); 

/ / Connecting topic. 
require_once (THEME_PATH. '/ index.php'); 

/ / Manage login. 
if (! empty ($ _GET [QUERY_VAR_MODULE])) 
( 
  / / Login form. 
  if (strcmp ($ _GET [QUERY_VAR_MODULE], 'login') === 0) 
  ( 
    UnlockSessionAndDestroyAllCokies (); 

    if (isset ($ _POST [ 'user']) & & isset ($ _POST [ 'pass'])) 
    ( 
      $ user = $ _POST [ 'user']; 
      $ pass = md5 ($ _POST [ 'pass']); 

      / / Check login. 
      if (@ mysql_query ( "SELECT id FROM cp_users WHERE name = '". addslashes ($ user). "' AND pass = '". addslashes ($ pass). "' AND flag_enabled = '1 'LIMIT 1") & & @ mysql_affected_rows () == 1) 
      ( 
        if (isset ($ _POST [ 'remember']) & & $ _POST [ 'remember'] == 1) 
        ( 
          setcookie (COOKIE_USER, md5 ($ user), COOKIE_LIVETIME, CP_HTTP_ROOT); 
          setcookie (COOKIE_PASS, $ pass, COOKIE_LIVETIME, CP_HTTP_ROOT); 
        ) 

        LockSession (); 
        $ _SESSION [ 'Name'] = $ user; 
        $ _SESSION [ 'Pass'] = $ pass; 
        / / UnlockSession (); 

        header ( 'Location:'. QUERY_STRING_BLANK. 'home'); 
      ) 
      else ShowLoginForm (true); 
      die (); 
    ) 

    ShowLoginForm (false); 
    die (); 
  ) 

  / / Output 
  if (strcmp ($ _GET [ 'm'], 'logout') === 0) 
  ( 
    UnlockSessionAndDestroyAllCokies (); 
    header ( 'Location:'. QUERY_STRING_BLANK. 'login'); 
    die (); 
  ) 
) 

////////////////////////////////////////////////// ///////////////////////////// 
/ / Check the login data. 
////////////////////////////////////////////////// ///////////////////////////// 

$ logined = 0, / / flag means, we zalogininy. 

/ / Log in session. 
LockSession (); 
if (! empty ($ _SESSION [ 'name']) & &! empty ($ _SESSION [ 'pass'])) 
( 
  if (($ r = @ mysql_query ( "SELECT * FROM cp_users WHERE name = '". addslashes ($ _SESSION [' name'])."' AND pass = ' ". addslashes ($ _SESSION [' pass']). " 'AND flag_enabled = '1' LIMIT 1 ")))$ logined = @ mysql_affected_rows (); 
) 
/ / Login through cookies. 
if ($ logined! == 1 & &! empty ($ _COOKIE [COOKIE_USER]) & &! empty ($ _COOKIE [COOKIE_PASS])) 
( 
  if (($ r = @ mysql_query ( "SELECT * FROM cp_users WHERE MD5 (name )='". addslashes ($ _COOKIE [COOKIE_USER ])."' AND pass = '". addslashes ($ _COOKIE [COOKIE_PASS]). " 'AND flag_enabled = '1' LIMIT 1 ")))$ logined = @ mysql_affected_rows (); 
) 
/ / Unable to login. 
if ($ logined! == 1) 
( 
  UnlockSessionAndDestroyAllCokies (); 
  header ( 'Location:'. QUERY_STRING_BLANK. 'login'); 
  die (); 
) 

/ / Get the user data. 
$ _USER_DATA = @ Mysql_fetch_assoc ($ r); 
if ($ _USER_DATA === false) die (mysql_error_ex ()); 
$ _SESSION [ 'Name'] = $ _USER_DATA [ 'name']; 
$ _SESSION [ 'Pass'] = $ _USER_DATA [ 'pass']; 

/ / Connecting language. 
if (@ strlen ($ _USER_DATA [ 'language'])! = 2 | |! SafePath ($ _USER_DATA [ 'language']) | |! file_exists ( 'system / lng .'.$_ USER_DATA [' language '].' . php'))$_ USER_DATA [ 'language'] = DEFAULT_LANGUAGE; 
require_once ( 'system / lng .'.$_ USER_DATA [' language'].'. php '); 

UnlockSession ();