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Vom Nutzer übermittelte Daten>>

Verwendung von Register Globals

Warnung

Dieses Feature ist seit PHP 5.3.0 DEPRECATED (veraltet). Sich auf dieses Feature zu verlassen ist in keiner Weise empfehlenswert.

Ein Feature von PHP zur Erhöhung der Sicherheit ist die Konfiguration von PHP mit register_globals = off. Mit Deaktivierung der Möglichkeit, irgendeine vom Benutzer übertragenen Variable in den PHP Code zu injizieren, können Sie die Anzahl "vergifteter" Variablen reduzieren, welche ein potentieller Angreifer zufügen könnte. Dieser benötigt mehr Zeit, um sich Übermittlungen auszudenken, und Ihre internen Variablen sind effektiv von den übergebenen Benutzervariablen isoliert.

Während dies den benötigten Aufwand mit PHP zu arbeiten leicht erhöht ist dargelegt, dass die Vorteile gegenüber dem Aufwand klar überwiegen.

Beispiel #9 Mit register_globals=on arbeiten

<?php
if ($username) {  // kann vom User mit get/post/cookies übermittelt werden
    
$good_login 1;
}

if (
$good_login == 1) { // kann vom User mit get/post/cookies übermittelt werden
    
fpassthru ("/highly/sensitive/data/index.html");
}
?>

Beispiel #10 Mit register_globals = off arbeiten

<?php
if($_COOKIE['username']){
    
// kann nur von einem Cookie kommen
    
$good_login 1;
    
fpassthru ("/highly/sensitive/data/index.html");
}
?>
Dies weise genutzt ist es auch möglich, präventive Messungen durchzuführen, um bei versuchten Vorstößen zu warnen. Wenn Sie im Voraus wissen, woher eine Variable kommen soll, können Sie prüfen, ob die übermittelten Daten nicht einen unpassenden Weg genommen haben. Obwohl dies nicht garantiert, dass Daten nicht nur ausgedacht sind, erfordert es von einem Angreifer, auch den richtigen Weg zu finden.

Beispiel #11 Entdecken einfacher Manipulationen von Variablen

<?php
if ($_COOKIE['username'] &&
    !
$_POST['username'] &&
    !
$_GET['username'] ) {
    
// Durchführen anderer Checks, ob der Benutzername gültig ist...
    
$good_login 1;
    
fpassthru ("/highly/sensitive/data/index.html");
} else {
   
mail("admin@example.com""Possible breakin attempt"$_SERVER['REMOTE_ADDR']);
   echo 
"Security violation, admin has been alerted.";
   exit;
}
?>
Natürlich bedeutet ein einfaches Deaktivieren von register_globals nicht, dass Ihr Code nun automatisch sicher ist. Jeder Teil mit Daten sollte auch auf andere Arten geprüft werden. Überprüfen Sie immer die Eingaben von Benutzern und initialisieren Sie Ihre Variablen! Um Ihre Skripte auf nicht initialisierte Variablen zu prüfen, können Sie error_reporting() so einstellen, dass Fehler des Levels E_NOTICE angezeigt werden.

Sie knnen die On und Off Einstellungen von register_globals emulieren, nheres hierzu finden Sie in den FAQ.

Hinweis: Superglobals: Hinweis zur Verfügbarkeit

Seit PHP 4.1.0 stehen superglobale Arrays wie $_GET, $_POST,$_SERVER, etc. zur Verfügung. Weitere Informationen können Sie dem Abschnitt zu superglobals entnehmen.


13 BenutzerBeiträge:
- Beiträge aktualisieren...
Andrew dot GuertinNO at SPAMuvm dot edu
19.06.2009 21:35
It's not mentioned anywhere, but it seems register globals also affects file uploads.

When a file is uploaded (with in this case, <input type="file" name="coconut">), the following variables appear:

["_FILES"]=>
array(1) {
  ["coconut"]=>
  array(5) {
    ["name"]=>
    string(14) "mozicon128.png"
    ["type"]=>
    string(9) "image/png"
    ["tmp_name"]=>
    string(14) "/tmp/phpWgtRBx"
    ["error"]=>
    int(0)
    ["size"]=>
    int(15113)
  }
}

When register globals is turned on, the following variables also appear:
["coconut_name"]=>
string(14) "mozicon128.png"
["coconut_type"]=>
string(9) "image/png"
["coconut"]=>
string(14) "/tmp/phpWgtRBx"
["coconut_size"]=>
int(15113)
lester burlap
23.03.2009 18:00
It would make this whole issue a lot less confusing for less-experienced PHP programmers if you just explained:

- $myVariable no longer works by default
- $_GET['myVariable'] works just fine

I'm embarrassed to say it's taken me six months since my ISP upgraded to PHP5 figure this out.  I've completely rewritten scripts to stop using GET variables altogether.

I'm dumb.
claude dot pache at gmail dot com
15.01.2009 14:52
Beware that all the solutions given in the comments below for emulating register_global being off are bogus, because they can destroy predefined variables you should not unset. For example, suppose that you have

<?php $_GET['_COOKIE'] == 'foo'; ?>

Then the simplistic solutions of the previous comments let you lose all the cookies registered in the superglobal "$_COOKIE"! (Note that in this situation, even with register_global set to "on", PHP is smart enough to not mess predefined variables such as  $_COOKIE.)

A proper solution for emulating register_global being off is given in the FAQ, as stated in the documentation above.
subarea AT webfire DOT biz
19.11.2008 12:38
your webspace provider has register-globals activated by standard and you don't have a chance to turn it off? no problem anymore, here is your solution...

<?php
// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
// this is just a workaround to kill all through register globals imported vars!
// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
// place this script after session_start() to be sure you unregister_globals('_SESSION');
// that's all, now all through "register_globals" assigned vars are deleted from scope.
// ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

if (ini_get('register_globals') == 1)
{
if (
is_array($_REQUEST)) foreach(array_keys($_REQUEST) as $var_to_kill) unset($$var_to_kill);
if (
is_array($_SESSION)) foreach(array_keys($_SESSION) as $var_to_kill) unset($$var_to_kill);
if (
is_array($_SERVER))  foreach(array_keys($_SERVER)  as $var_to_kill) unset($$var_to_kill);
                                                                        unset(
$var_to_kill);
}
?>

hope you like it ;)

greetz subarea
 
georg_gruber at yahoo dot com
27.10.2008 22:21
BEWARE of using register_globals = On, it's not only bad karma but highly dangerous.

Consider the following coding:

<?php
// assume $_SESSION['user'] = array('Hello', 'World');
// assume session_start() was called somewhere before.

   
print('<pre>Contents of array $_SESSION[\'user\']');
   
print_r($_SESSION['user']);
    print(
'<hr>Contents of array $user (PHP SETUP register_globals = On)');
   
print_r($user);
    print(
'</pre>');
?>

If you manipulate $user you'll manipulate $_SESSION['user'] as well with PHP SETUP register_globals = On.

So please avoid it at any cost, no serious programmer would ever want to have register_globals = On.
bohwaz
31.08.2008 23:39
<?php

// Unregister_globals: unsets all global variables set from a superglobal array
// --------------------
// This is useful if you don't know the configuration of PHP on the server the application
// will be run
// Place this in the first lines of all of your scripts
// Don't forget that the register_global of $_SESSION is done after session_start() so after
// each session_start() put a unregister_globals('_SESSION');

function unregister_globals()
{
    if (!
ini_get('register_globals'))
    {
        return
false;
    }

    foreach (
func_get_args() as $name)
    {
        foreach (
$GLOBALS[$name] as $key=>$value)
        {
            if (isset(
$GLOBALS[$key]))
                unset(
$GLOBALS[$key]);
        }
    }
}

unregister_globals('_POST', '_GET', '_COOKIE', '_REQUEST', '_SERVER', '_ENV', '_FILES');

?>
moore at hs-furtwangen dot de
14.07.2008 22:19
I had a look at the post from Dice, in which he suggested the function unregister_globals(). It didn't seem to work - only tested php 4.4.8 and 5.2.1 - so I made some tweaking to get it running. (I had to use $GLOBALS due to the fact that $$name won't work with superglobals).

<?php
//Undo register_globals
function unregister_globals() {
    if (
ini_get('register_globals')) {
       
$array = array('_REQUEST', '_FILES');
        foreach (
$array as $value) {
            if(isset(
$GLOBALS[$value])){
                foreach (
$GLOBALS[$value] as $key => $var) {
                    if (isset(
$GLOBALS[$key]) && $var === $GLOBALS[$key]) {
                       
//echo 'found '.$key.' = '.$var.' in $'.$value."\n";                   
                       
unset($GLOBALS[$key]);
                    }
                }
            }
        }
    }
}
?>

The echo was for debuging, thought it might come in handy.
fab dot mariotti at [google]gmail dot com
16.04.2008 21:59
For my application I defined two functions:
wit_set_gv('space','key','value')
wit_get_gv('space','key')
Forgive the "wit_" prefix but the gv stays for Global Variable.

Maybe I should start with a simple version:
wit_set_gv('key','value')
wit_get_gv('key')

This way you would set or get a global/session value.
The register_globals (on or off), session state and/or
superglobal variables will be handled by these functions.

I did add a 'space' item because I wanted to have control
on what goes to/comes from where. As an example if I call:
wit_get_gv('WIT_CONF','URL')
I know that I have to check for a global variable named
WIT_CONF which also gives me a positive responce
on isset($WIT_CONF['URL']). In this case $WIT_CONF
is global and static. But I can also set up a $WIT_STATE
variable which will represent the state of the transaction.
Using the code of WIT_set_gv() and WIT_get_gv(), with the help
of a simple few lines (in my case: include globals.inc.php)
definition script I handle this problem.

In my case, for example, if 'WIT_STATE' (or other names)
is not a defined globally available variable I default to check
for a session variable.

For example you might warn or stop if a requested named variable
matches a $_POST, $_GET or $_SESSION variable name while you
do not expect so. i.e. all my private data has a wit_ prefix
but no public request has (shouldn't have) this prefix.

Oopss. I do realize that this comment might not be in the proper
place. i.e. "register_globals". Indeed it might give some advice
to users still using register_globals and willing to change the
code for a "better" solution. Of course                                                                                the simple switching to "register_globals = off" might not solve
the securities issues.

Cheers
F
Dice
16.04.2008 6:46
To expand on the nice bit of code Mike Willbanks wrote and Alexander tidied up, I turned the whole thing in a function that removes all the globals added by register_globals so it can be implemented in an included functions.php and doesn't litter the main pages too much.

<?php
//Undo register_globals
function unregister_globals() {
    if (
ini_get(register_globals)) {
       
$array = array('_REQUEST', '_SESSION', '_SERVER', '_ENV', '_FILES');
        foreach (
$array as $value) {
            foreach (
$GLOBALS[$value] as $key => $var) {
                if (
$var === $GLOBALS[$key]) {
                    unset(
$GLOBALS[$key]);
                }
            }
        }
    }
}
?>
Ruquay K Calloway
1.04.2008 15:59
While we all appreciate the many helpful posts to get rid of register_globals, maybe you're one of those who just loves it.  More likely, your boss says you just have to live with it because he thinks it's a great feature.

No problem, just call (below defined):

<?php register_globals(); ?>

anywhere, as often as you want.  Or update your scripts!

<?php
/**
 * function to emulate the register_globals setting in PHP
 * for all of those diehard fans of possibly harmful PHP settings :-)
 * @author Ruquay K Calloway
 * @param string $order order in which to register the globals, e.g. 'egpcs' for default
 */
function register_globals($order = 'egpcs')
{
   
// define a subroutine
   
if(!function_exists('register_global_array'))
    {
        function
register_global_array(array $superglobal)
        {
            foreach(
$superglobal as $varname => $value)
            {
                global $
$varname;
                $
$varname = $value;
            }
        }
    }
   
   
$order = explode("\r\n", trim(chunk_split($order, 1)));
    foreach(
$order as $k)
    {
        switch(
strtolower($k))
        {
            case
'e':    register_global_array($_ENV);        break;
            case
'g':    register_global_array($_GET);        break;
            case
'p':    register_global_array($_POST);        break;
            case
'c':    register_global_array($_COOKIE);    break;
            case
's':    register_global_array($_SERVER);    break;
        }
    }
}
?>
Tumasch
13.12.2007 14:50
In addition to Mike Willbanks post:

Put this to the beginning of every file or to a functions.inc.php and call it every time before start working with user variables.
This will prevent problems with wrong initalized variables or users who try to break your application.

And this has an extra bonus: Applications which still work are also register_globasl = off enabled!

<?php
//
// If register_globals is on, delete all variables exept the ones in the array
//
if (ini_get('register_globals')) {
    foreach (
$GLOBALS as $int_temp_name => $int_temp_value) {
        if (!
in_array($int_temp_name, array (
               
'GLOBALS',
               
'_FILES',
               
'_REQUEST',
               
'_COOKIE',
               
'_SERVER',
               
'_ENV',
               
'_SESSION',
               
ini_get('session.name'),
               
'int_temp_name',
               
'int_temp_value'
           
))) {
            unset (
$GLOBALS[$int_temp_name]);
        }
    }
}
//
// Now, (re)import the variables
//
if (isset ($_REQUEST['pass']))
   
$ext_pass = $_REQUEST['pass'];
if (isset (
$_REQUEST['user']))
   
$ext_user = $_REQUEST['user'];
if (isset (
$_REQUEST['action']))
   
$ext_action = $_REQUEST['action'];
//
// Cleanup entries
//
$int_pass = (isset ($ext_pass) ? preg_replace("'[^A-Z]'", "", $ext_pass) : '');
$int_user = (isset ($ext_user) ? preg_replace("'[]A-Za-z0-9áäàâãëèéêïìîóöòôõúüùû \.^\$\!\_-()'", "", $ext_user) : '');
$int_action = (isset ($ext_action) ? intval($ext_action) : '');
//
// Import Session variables
//
if (isset ($_SESSION)) {
    foreach (
$_SESSION as $int_temp_key => $int_temp_value) {
        if (
$int_temp_value != '') {
            $
$int_temp_key = $int_temp_value;
        }
    }
}
//
// Import Cookie variables
//
if (isset ($_COOKIE)) {
    foreach (
$_COOKIE as $int_temp_key => $int_temp_value) {
        if (
$int_temp_value != '') {
            $
$int_temp_key = $int_temp_value;
        }
    }
}
//
// From here on, work only with $int_ variables and you're safe!
//
?>

With this you can prevent a lot of different problems!
alan hogan
20.07.2007 5:08
Useful for shared hosting or scripts that you are sharing with other people.
<?php
// Effectively turn off dangerous register_globals without having to edit php.ini
if (ini_get(register_globals))  // If register_globals is enabled
{ // Unset $_GET keys
 
foreach ($_GET as $get_key => $get_value) {
    if (
ereg('^([a-zA-Z]|_){1}([a-zA-Z0-9]|_)*$', $get_key)) eval("unset(\${$get_key});");
  }
// Unset $_POST keys
 
foreach ($_POST as $post_key => $post_value) {
    if (
ereg('^([a-zA-Z]|_){1}([a-zA-Z0-9]|_)*$', $post_key)) eval("unset(\${$post_key});");

  }
// Unset $_REQUEST keys
 
foreach ($_REQUEST as $request_key => $request_value) {
    if (
ereg('^([a-zA-Z]|_){1}([a-zA-Z0-9]|_)*$', $request_key)) eval("unset(\${$request_key});");
  }
}
?>
dav at thedevelopersalliance dot com
18.12.2003 7:38
import_request_variables() has a good solution to part of this problem - add a prefix to all imported variables, thus almost eliminating the factor of overriding internal variables through requests. you should still check data, but adding a prefix to imports is a start.



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