错误报告
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.
使用 Register Globals
可能 PHP 中最具争议的变化就是从 PHP » 4.2.0 版开始配置文件中 register_globals 的默认值从 on 改为 off 了。对此选项的依赖是如此普遍以至于很多人根本不知道它的存在而以为 PHP 本来就是这么工作的。本节会解释用这个指令如何写出不安全的代码，但要知道这个指令本身没有不安全的地方，误用才会。
当 register_globals 打开以后，各种变量都被注入代码，例如来自 HTML 表单的请求变量。再加上 PHP 在使用变量之前是无需进行初始化的，这就使得更容易写出不安全的代码。这是个很艰难的抉择，但 PHP 社区还是决定默认关闭此选项。当打开时，人们使用变量时确实不知道变量是哪里来的，只能想当然。但是 register_globals 的关闭改变了这种代码内部变量和客户端发送的变量混杂在一起的糟糕情况。下面举一个错误使用 register_globals 的例子：
Example#1 错误使用 register_globals = on 的例子
<?php
// 当用户合法的时候，赋值 $authorized = true
if (authenticated_user()) {
$authorized = true;
}
// 由于并没有事先把 $authorized 初始化为 false，
// 当 register_globals 打开时，可能通过GET auth.php?authorized=1 来定义该变量值
// 所以任何人都可以绕过身份验证
if ($authorized) {
include "/highly/sensitive/data.php";
}
?>
当 register_globals = on 的时候，上面的代码就会有危险了。如果是 off，$authorized 就不能通过如 URL 请求等方式来改变，这样就好多了，尽管初始化变量是一个良好的编程习惯。比如说，如果在上面的代码执行之前加入 $authorized = false 的话，无论 register_globals 是 on 还是 off 都可以，因为用户状态被初始化为未经认证。
另一个例子是关于会话的。当 register_globals = on 的时候，$username 也可以用在下面的代码中，但要意识到 $username 也可能会从其它途径进来，比如说通过 URL 的 GET。
Example#2 使用会话时同时兼容 register_globals on 和 off 的例子
<?php
// 我们不知道 $username 的来源，但很清楚 $_SESSION 是
// 来源于会话数据
if (isset($_SESSION['username'])) {
echo "Hello <b>{$_SESSION['username']}</b>";
} else {
echo "Hello <b>Guest</b><br />";
echo "Would you like to login?";
}
?>
采取相应的预防措施以便在伪造变量输入的时候给予警告是完全有可能的。如果事先确切知道变量是哪里来的，就可以检查所提交的数据是否是从不正当的表单提交而来。不过这不能保证变量未被伪造，这需要攻击者去猜测应该怎样去伪造。如果不在乎请求数据来源的话，可以使用 $_REQUEST 数组，它包括了 GET、POST 和 COOKIE 的所有数据。详情可参见本手册的来自 PHP 之外的变量。
Example#3 探测有害变量
<?php
if (isset($_COOKIE['MAGIC_COOKIE'])) {
// MAGIC_COOKIE 来自 cookie
// 这样做是确保是来自 cookie 的数据
} elseif (isset($_GET['MAGIC_COOKIE']) || isset($_POST['MAGIC_COOKIE'])) {
mail("admin@example.com", "Possible breakin attempt", $_SERVER['REMOTE_ADDR']);
echo "Security violation, admin has been alerted.";
exit;
} else {
// 这一次请求中并没有设置 MAGIC_COOKIE 变量
}
?>
当然，单纯地关闭 register_globals 并不代表所有的代码都安全了。对于每一段提交上来的数据，都要对其进行具体的检查。永远要验证用户数据和对变量进行初始化！把 error_reporting() 设为 E_NOTICE 级别可以检查未初始化的变量。
更多关于模拟 register_globals 为 on 或 off 的信息，请见此 FAQ。
Note: Superglobals 可用性说明 自 PHP 4.1.0 起，可以使用超全局数组变量例如 $_GET，$_POST 和 $_SERVER 等等。更多信息请阅读手册中的 superglobals。
add a note
User Contributed Notes使用 Register Globals
moore at hs-furtwangen dot de
15-Jul-2008 04:19
15-Jul-2008 04:19
stranger at teuton dot org
10-Jul-2008 07:48
10-Jul-2008 07:48
RE: Anonymous on oirinely at yahoo dot com
Actually oirinely is correct. With register_globals on any key in $_SESSION becomes a global variable when session_start() happens. This means that assigning a value to any variable that has the same name as any existing $_SESSION key (when register_globals is on and session_start() has happened) is the same as assigning to $_SESSION
e.g.
<?php
session_start();
$_SESSION['foo'] = 1;
$foo = 2;
echo $_SESSION['foo'];
?>
result = 1
Anonymous
29-Apr-2008 07:14
29-Apr-2008 07:14
oirinely at yahoo dot com -
that piece of code will not print another value unless it looks like this:
<?php
$_SESSION['value'] = 'some value';
$value = 'another value';
$_SESSION['value'] = $value; // with this line in, $_SESSION['value'] now equals $value so it will be insecure
echo $_SESSION['value'];
?>
fab dot mariotti at [google]gmail dot com
17-Apr-2008 03:59
17-Apr-2008 03:59
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-Apr-2008 12:46
16-Apr-2008 12:46
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
01-Apr-2008 09:59
01-Apr-2008 09:59
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;
$$varname = $value;
}
}
}
$order = explode("\r\n", trim(chunk_split($order, 1)));
foreach($order as $k)
{
switch(strtolower($k))
{
case 'e': register_global_array($_ENV); break;
case 'g': register_global_array($_GET); break;
case 'p': register_global_array($_POST); break;
case 'c': register_global_array($_COOKIE); break;
case 's': register_global_array($_SERVER); break;
}
}
}
?>
subarea
21-Mar-2008 12:43
21-Mar-2008 12:43
If you have no access to php.ini and the solution with
the .htaccess entry (php_flag register_globals 0)
also doesn't work or you are just a little bit paranoid,
you can use the following script.
this is just a workaround to kill all (through register globals) imported vars!
<?php
foreach(array_keys($_REQUEST) as $var_to_kill) unset($$var_to_kill);
foreach(array_keys($_SESSION) as $var_to_kill) unset($$var_to_kill);
foreach(array_keys($_SERVER) as $var_to_kill) unset($$var_to_kill);
unset($var_to_kill);
?>
if you like it, just drop me a line...
greetz subarea
dot dot dot dot dot alexander at gmail dot com
09-Mar-2008 10:19
09-Mar-2008 10:19
@ Mike Willbanks's post
This is an even cleaner version of your code:
<?php
if( ini_get(register_globals) ) {
/* genocide the damn registered globals if they are on */
foreach( $_REQUEST as $key => $var ){
if( $var === $$key ){
unset($$key);
}
}
}
?>
oirinel at yahoo dot com
19-Dec-2007 04:35
19-Dec-2007 04:35
when using register_globals=On be careful since using something like:
$_SESSION['value'] = 'some value';
$value = 'another value';
echo $_SESSION['value']; // !!! will print 'another value' !!!!
Hope this will save someone from headaches and from loosing hours!
Tumasch
13-Dec-2007 09:50
13-Dec-2007 09:50
In addition to Mike Willbanks post:
Put this to the beginning of every file or to a functions.inc.php and call it every time before start working with user variables.
This will prevent problems with wrong initalized variables or users who try to break your application.
And this has an extra bonus: Applications which still work are also register_globasl = off enabled!
<?php
//
// If register_globals is on, delete all variables exept the ones in the array
//
if (ini_get('register_globals')) {
foreach ($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!
Mike Willbanks
05-Sep-2007 11:40
05-Sep-2007 11:40
Sorry the last php code I submitted was formatted nice but I changed some things for readability and didn't implement it across the board. Here is the correct code:
<?php
if (ini_get(register_globals)) {
$rg = array_keys($_REQUEST);
foreach($rg as $var)
{
if ($_REQUEST[$var] === $$var)
{
unset($$var);
}
}
}
?>
Mike Willbanks
30-Aug-2007 02:15
30-Aug-2007 02:15
Alans code may get rid of globals but it is slow since it is doing regular expressions on each of the input items. Then to add on more time the code is being passed through eval.
Besides the slower performance, his code is not checking to see if the variable may have been changed at any state before this code is being done.
There might be auto_prepended files or include files that might need to run before it. He is also going through get and post and lastly request which is a little silly seeing as request will contain the get, post and cookie so he has run get and post twice.
Here is a more effective fix that will take all the keys in request which become variable names and checks to make sure that the variables match then unsets the element.
<?php
if (ini_get(register_globals)) {
$rg = array_keys($_REQUEST);
foreach($rg as $var)
{
if ($_REQUEST[$v] === $$v)
{
unset($$v);
}
}
}
?>
alan hogan
20-Jul-2007 11:08
20-Jul-2007 11:08
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});");
}
}
?>
Timbo
14-Jul-2007 11:25
14-Jul-2007 11:25
In response to the above post by Caliwebman at yahoo dot com, a.k.a. "Gentle Warrior" who complained about the lack of documentation on register_globals:
I think this code snippet will address the *main* source of his confusion:
<?
function readyToBeAProgrammer()
{
$stuff=$_URINALYSIS['test'];
if($stuff == THC)
{
return false;
}
else
{
return true;
}
// register_globals is all about knowing where your variables are really coming from
// what if a malicious user tried to pass off
// $stuff=$_GET['someone_elses_drop']; // as $stuff ?
// preventing this kind of substitution is the whole point
// of disabling register_globals
}
if(!readyToBeAProgrammer())
{
die("Switch to coffee, man!");
}
?>
P.S., let's give it up in appreciation for the moderators who must sit though and clean up these boards, facetious posts like mine included...
caliwebman at yahoo dot com
10-Jul-2007 06:29
10-Jul-2007 06:29
U know what I find incredibly insane? The fact that no where on the first pages <<<PLURAL does anyone even suggest where to find this code. And IF it exists in a file called "register_globals-etc..." than I have no clue why none of my sites have this file. It amazes me that we here on this side have made things so incredibly difficult on ourselves and the newer coders. Why? I thought that was what Microsoft was doing but quite honestly follks, we here on this side have MS beat when it comes to making things MUCH more of a challenge than they need be.
PLEASE, please dumb things down. And if you can't? ASK someone who is NOT in your bubble of code to review what you are writing in your dirstructions.... directions.... ask someoen like your MOM or DAD who know nothing of the code.
We sure would get going mch more quickly if we all paid attenttion to this simple rule.... and lastly, the front end designers are finally getting it together..... thank you, but again, remember, THE 3 CLICK RULE!!!
Peace,
Gentle Warrior
Scott
29-Jun-2007 01:19
29-Jun-2007 01:19
I couldn't get any of the suggested ways to disable register_globals to work in what I believe to be an Apache environment, where even phpinfo() is disabled. I finally had to resort to
foreach(array_keys($_REQUEST) as $field)
{
unset(${$field});
}
to get the $_REQUEST array without auto-setting all the request variables. I'm somewhat new to the whole PHP thing and wonder if there is a downside to this that I don't see.
someone at example dot com
18-Apr-2007 03:14
18-Apr-2007 03:14
In reply to yyalcinkaya at ku edu tr you could just do this with $_REQUEST:
foreach($_REQUEST as $k => $v)
{
${$k} = $v;
}
...though doing something like this is asking for a world of trouble IMHO.
yyalcinkaya at ku edu tr
28-Mar-2007 06:37
28-Mar-2007 06:37
if you want to keep register_globals off you can use this codes instead.
foreach($_POST AS $key => $value) {
${$key} = $value;
}
foreach($_GET AS $key => $value) {
${$key} = $value;
}
alan at xensource dot com
16-Nov-2005 01:00
16-Nov-2005 01:00
From the PHP Manual page on Using register_globals:
Do not use extract() on untrusted data, like user-input ($_GET, ...). If you do, for example, if you want to run old code that relies on register_globals temporarily, make sure you use one of the non-overwriting extract_type values such as EXTR_SKIP and be aware that you should extract in the same order that's defined in variables_order within the php.ini.
Dexter at dexpark dot com
06-Nov-2005 10:59
06-Nov-2005 10:59
For Apache users or webhosters, you can set the
php_flag register_globals on/off in a VirtualHost context.
dyer85 at gmail dot com
05-Nov-2005 02:10
05-Nov-2005 02:10
I'd suggest taking a look at php.net's source code for these user notes, if you want to get ideas on some nice ways to collect and validate user data.
http://php.net/source.php?url=/manual/add-note.php
hbinduni at gmail dot com
30-Oct-2005 05:06
30-Oct-2005 05:06
[quote]
If you're under an Apache environment that has this option enabled, but you're on shared hosting so have no access to php.ini, you can unset this value for your own site by placing the following in an .htaccess file in the root:
php_flag register_globals 0
[/quote]
adding php_flag in .htaccess under apache 2 will cause internal server error. according to apache 2 manual, php_flag should goes to <virtual> or <directory> section.
ramosa (0) gmail dotty com
25-Sep-2005 12:24
25-Sep-2005 12:24
Here's a one liner that works both with register globals on or off, and is even secure enough when it's on, as you make sure you init the var.
Using the ?: operator
$variable = isset($_GET["variable"]) ? $_GET["variable"] : "";
kcinick at ciudad dot com dot ar
19-May-2005 06:12
19-May-2005 06:12
if you plan to use php_admin_value register_globals [0-1] inside <VirtualHost> in apache, forget it, it don't show any error messages in the configuration, but at the time of running, it enable and disables register_globals at random request, if you need to customize this param to multiple virtual host, put it in a <Directory> directives, it works fine there...
PD: same for safe_mode, etc...
ryanwray at gmail dot com
24-Nov-2004 11:03
24-Nov-2004 11:03
In reply to ben at nullcreations dot net:
This is true of the super-global $_SESSION, as it will always be processed last (it is not considered in variables_order directive)
However, it is possible to over-write other data, namely GET, POST, COOKIE, ENVIROMENT and SERVER.
Of course, what you can overwrite will depend on the directive variables_order - by default, you could overwrite GET and POST data via COOKIE (because cookie data is processed last out of the three which should not really be of great concern.
My below code is irrelevant unless extract or another method which does the same thing (ie. I have seen variable variables used before to reach the same affect) is used.
ben at nullcreations dot net
23-Nov-2004 08:53
23-Nov-2004 08:53
Just a note to all the people who think $_SESSION can be poisoned by register_globals - it can't.
Consider the fact that GET/POST/COOKIE is Processed *before* sessions are. This means that even if you have register_globals on, and they write to $_SESSION, $_SESSION will just get reset again with the appropriate values.
Some people take to using extract() as a means to simulate register_globals in scripts where they're not sure what the server environment will be - this is when you should worry about such things. The reason is because extract() can concievably occur after GET/POST/COOKIE and SESSION processing.
snarkles <anything at $myname dot net>
20-May-2004 03:06
20-May-2004 03:06
If you're under an Apache environment that has this option enabled, but you're on shared hosting so have no access to php.ini, you can unset this value for your own site by placing the following in an .htaccess file in the root:
php_flag register_globals 0
The ini_set() function actually accomplishes nothing here, since the variables will have already been created by the time the script processes the ini file change.
And since this is the security chapter, just as a side note, another thing that's helpful to put into your .htaccess is:
<Files ".ht*">
deny from all
</Files>
That way no one can load .htaccess in their browser and have a peek at its contents.
Sorry, not aware of a similar workaround for IIS. :\
dav at thedevelopersalliance dot com
18-Dec-2003 02:38
18-Dec-2003 02:38
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.