Глава 32. Сокрытие PHP

В общем случае внесение неясности ненамного улучшает защищенность системы. Но бывают случаи, когда следует использовать малейшую возможность.

Несколько несложных методик могут помочь вам скрыть PHP, что усложняет работу потенциального взломщика, который пытается найти брешь в вашей системе. Установив опцию expose_php = off в конфигурационном файле php.ini, вы уменьшите количество доступной хакеру информации.

Еще одна методика заключается в настройке веб-сервера таким образом, чтобы он обрабатывал файлы с различными расширениями как PHP-скрипты. Это можно указать как в .htaccess файлах, так и конфигурационном файле Apache. В таком случае вы сможете использовать при написании кода нестандартные расширения:
Пример 32-1. Маскировка PHP под другие языки программирования
# Теперь PHP-скрипты могут иметь те же расширения, что и другие языки программирования AddType application/x-httpd-php .asp .py .pl
Или скрыть его совсем:
Пример 32-2. Использование неизвестных расширений для PHP-скриптов
# Теперь PHP-скрипты могут иметь неизвестные типы файлов AddType application/x-httpd-php .bop .foo .133t
Также можно спрятать его под видом HTML-кода, что приведет к потере производительности, так как все HTML файлы будут обрабатываться как PHP-код:
Пример 32-3. Маскировка PHP-кода под html-файлы
# Теперь PHP-скртпы могут выглядеть как обыкновенный HTML AddType application/x-httpd-php .htm .html
Чтобы достичь желаемого эффекта, вы должны переименовать все ваши скрипты в соответствии с выбранным вами расширением. Описанное в этом разделе документации повышение безопасности через сокрытие PHP имеет мало недостатков при небольших затратах.

Сокрытие PHP

marpetr at NOSPAM dot gmail dot com
11-Apr-2006 05:18


I think the best way to hide PHP on Apache and Apache itself is this:



httpd.conf

-------------

# ...

# Minimize 'Server' header information

ServerTokens Prod

# Disable server signature on server generated pages

ServerSignature Off

# ...

# Set default file type to PHP

DefaultType application/x-httpd-php

# ...



php.ini

------------

; ...

expose_php = Off

; ...



Now the URLs will look like this:

http://my.server.com/forums/post?forumid=15



Now hacker knows only that you are using Apache.

ahmad at unikomcenter dot com
05-Mar-2006 10:05


I am use this script to hidding PHP:



index.php

--------------

<?php



// PARSING QUERY STRING

$QS=explode("&",$_SERVER['QUERY_STRING']);

$QS=explode('/',$QS[0]);



// IF Modul is Undefined set it to index

if (!$QS[0]) $MODUL='index';

else $MODUL=strtolower($QS[0]);



// WE can make a Variable $_QUERY

// for alternative _GET

for ($i=1;$i<count($QS);$i+=2)

{

    $_QUERY[$NVAR]=$NVAR=$QS[$i];

    $$NVAR=$QS[$i+1];

}



// Check the Modul is exists?

if (!file_exists("modul_directory/{$MODUL}.php"))

    $MODUL="index";



#### THIS IS EXAMPLE TO IMPLEMENTATION THE SCRIPT

// Load The Template

include("template.php");

// Load The Module

include("modul_directory/{$MODUL}.php");

// Load The Footer

include("footer.php");



?>



we can access the modul in URL like this:

=================================



www.example.com/?forum/topic/20

- it mean load the modul forum.php, and set the _QUERY['topic']=20



www.foo.com/?voting/id/54/type/piechart&choice=2

- it mean load the modul voting.php, and set the _QUERY['id']=54 and _QUERY['type']='piechart' and set _GET['choice']=2

eric at ericwing dot net
20-Jan-2006 09:20


Something that has not been mentioned here is also the PHPSESSION id that will be displayed in the URL when passing it from page to page using GET.  If users have cookies set to off, this will be visible. This can be reset before any session_start() call with ini_set(). Be aware however that this can't be changed in this way if you use autho session start.

dyer85 at gmail dot com
31-Dec-2005 12:55


Although it's probably obvious to most people, Yavuz Darendelioglu's post below utilizes a method that will only work on a *nix OS, not Windows, and probably not Mac.



Also, his regex uses some superfluous matching, instead, write the redirect like so: (you don't really need to use absolute path when redirecting to a resource on the same server, either):



RedirectMatch (?:awstats|xmlrpc) /deny.php

28-Dec-2005 07:29


Even you hide your PHP, requests for bugy scripts still come. 

No matter whether you have the script on your server or not.



You can make an additional step for those requests. Since the host now trying that buggy script  then, in the future when a new bug arises it will be tried  by that host again with a high possibility. So banning that host completey at its first attempt may be a good idea. For  this,



1- Add Permanent links for those requests in your httpd.conf:

RedirectMatch permanent (.*)awstats(.*)$ http://your_server/your_script.html



RedirectMatch permanent (.*)xmlrpc(.*)$ http://your_server/your_script.html

and add whatever you want to ban.



2- Write following code in your_script.html

<?

$host= $_SERVER['REMOTE_ADDR'];

$dropit = "iptables -A INPUT -i eth0 -p tcp -s $host -m multiport --destination-ports 80,25,22 -j DROP";

shell_exec($dropit);

exit

?>



Yavuz Darendelioglu

user at pampelhuber dot invalid
18-Dec-2005 04:32


It is unnecessary, to let every Pampelhuber inspect your 'php.ini' files.

Put the following into the .htaccess of your htdocuments' root:



#Obscure 'php.ini' files (where they exist)

RedirectMatch 404 .*php\.ini$

jtw90210
30-Jun-2005 01:19


In order to get the PATH_INFO to work in order to pass parameters using a hidden program/trailing slash/"pretty url" in more recent versions of PHP you MUST add "AcceptPathInfo On" to your httpd.conf. 



AddType application/x-httpd-php .php .html

AcceptPathInfo On



Try it out with your phpinfo page and you'll be able to search for PATH_INFO. 



http://yourserver.com/myphpinfo.php/showmetheway



If you want to drop the .php use one or both of these:

DefaultType application/x-httpd-php

ForceType application/x-httpd-php

25-May-2005 01:06


You could also do this in .htaccess when you use Apache and your configuration allows you to override :



<Files test>

    ForceType application/x-httpd-php

</Files>



That way, you can use the URL test?pop=true without having to fake it by using test/index.php.



See the Apache manual for more info: http://httpd.apache.org/docs/mod/mod_mime#forcetype

benjamin at sonntag dot fr
24-May-2005 09:14


In response to the previous messages, for apache, there is a easier way to set files without "." to be executed by PHP, just put this in a ".htaccess" file : 



DefaultType  application/x-httpd-php

dimitar at bastun dot net
17-Jan-2005 09:13


In case there are an Internal Server error(error 500) using the old code below in an .htaccess file, you can replace it with the code modification that must solve the problem.



Old code

-----------



<Files ~ "^[^\.]+$">

       ForceType application/x-httpd-php

</Files>



Replacement of the code above(code modification)

------------------------------------------------------------



AddHandler server-parsed .php

<Files ~ "^[^\.]+$">

SetHandler application/x-httpd-php

</Files>



Regards,

Dimitar Tanev

Nikolai-Zujev-(at)-Gmail-dot-Com
22-Sep-2004 12:22


Assign files w/o extension to php interpreter

without using ReWrite module



[clip httpd.conf]



<Files ~ "^[^\.]+$">

        ForceType application/x-httpd-php

</Files>



[/clip]

php at vfmedia dot de
15-Jun-2004 06:21


I�ve found an easy way to hide php code and the uri is searchable by google and others...(only for unix or linux)



At first I have some rules in my hide.conf (i made an extra .conf for it (apache 2.0))



For example when I want to mask the index.php



<Files index>

 ForceType application/x-httpd-php

 </Files>



My problem is, that my code should be readable...



so I made an extra folder for example srv/www/htdocs/static_output



My phpcode is in the includefolder....(for ex. mnt/source/index.php)



Then I made a link in the shell  > ln mnt/source/index.php srv/www/htdocs/static_output/index



So the code is readable (with .php extension) in my includefolder and there is only the link in the srv folder without extension(which is called by the browser...).

12-May-2004 08:20


Keep in mind, if your really freaked out over hiding PHP, GD will expose you.



Go ahead - make an image with GD and open with a text editor.. Somewhere in there you'll see a comment with gd & php all over it.

php at user dot net
10-Apr-2004 06:36


What about this in a .htaccess file :



RewriteEngine on

RewriteRule    ^$    /index.php    [L]

RewriteRule    ^([a-zA-Z0-9\-\_/]*)/$    /$1/index.php    [L]

RewriteRule    ^([a-zA-Z0-9\-\_/]*)\.(html|htm)$    /$1.php    [L]

RewriteRule    ^([a-zA-Z0-9\-\_/]*)$    /$1.php    [L]



Typing "sub.domain.foo/anything" loads "/anything/index.php" if 'anything' is a directory, else it loads "/anything.php".



I'm sure you can find mutch better, but it works great on my site :)

mmj
14-Mar-2004 05:58


You can see if somebody's using PHP just by adding the following to the end of the URL:

?=PHPB8B5F2A0-3C92-11d3-A3A9-4C7B08C10000

If the page is using PHP, this will show the PHP credits.



Setting expose_php to Off in php.ini prevents this.

Elora at alexandria dot cc
13-Feb-2004 03:30


<bminton at efn dot org>'s suggestion won't work. All someone has to do is look at "foo.com/dir/" and try "foo.com/dir/index.html", "foo.com/dir/index.php", "foo.com/dir/index.cgi", until no 403/404 is returned.

ldemailly at qualysNOSPAM dot com
27-Oct-2003 08:17


adding MultiViews to your apache Options config

lets you hide/omit .php in the url without any rewriting, etc...

l0rdphi1 at liquefyr dot com
21-Jul-2003 04:02


More fun includes files without file extensions.



Simply add that ForceType application/x-httpd-php bit to an Apache .htaccess and you're set.



Oh yea, it gets even better when you play with stuff like the following:



substr($_SERVER['PATH_INFO'],1);



e.g. www.yoursite.com/somepage/55



And:



foreach ( explode('/',$_SERVER['PATH_INFO']) as $pair ) {

    list($key,$value) = split('=',$pair,2);

    $param[$key] = stripslashes($value);

}



e.g. www.yoursite.com/somepage/param1=value1/param2=value2/etc=etc



Enjoy =)

Bryce Nesbitt at Obviously.COM
27-Mar-2003 08:24


Using the .php extension for all your scripts is not necessary, and in fact can be harmful (by exposing too much information about your server, and by limiting what you can do in the future without breaking links). There are several ways to hide your .php script extension:



(1) Don't hard code file types at all.  Don't specify any dots, and most web servers will automatically find your .php, .html, .pdf, .gif or other matching file. This is called canonical URL format:

     www.xxxxxx.com/page

    www.xxxxxx.com/directory/

This gives you great flexibility to change your mind in the future, and prevents Windows browsers from making improper assumptions about the file type.



(2) In an Apache .htaccess file use:

    RewriteEngine on

    RewriteRule page.html page.php



(3) Force the webserver to interpret ALL .html files as .php:

    AddType application/x-httpd-php .php3 .php .html

bminton at efn dot org
27-Feb-2003 12:05


Another technique is to have every file be named index.php and be in it's own directory.  Then instead of using for instance http://my.site/foo.php you could use http://my.site/foo/ where foo is a directory with a file called index.php in it.

29-Jan-2003 10:53


PS. If you want to use pretty URLs (i.e. hide your .php extensions) AND you have safe-mode=on, the previous example (ForceType) won't work for you.  The problem is that safe-mode forces Apache to honor trailing characters in a requested URL.  This means that:



http://www.foo.com/home 



would still be processed by the home script in our doc root, but for:



http://www.foo.com/home/contact_us.html



apache would actually look for the /home/contact_us.html file in our doc root.



The best solution I've found is to set up a virtual host (which I do for everything, even the default doc root) and override the trailing characters handling within the virtual host.  So, for a virtual host listening on port 8080, the apache directives would look like this:



<VirtualHost *:8080>

    DocumentRoot /web/doc_root

    Alias /home "/web/doc_root/home.php"

    AcceptPathInfo On

</VirtualHost>



Some people might question why we are overriding the trailing characters handling (with the AcceptPathInfo directive) instead of just turning safe-mode=off.  The reason is that safe mode sets global limitations on the entire server, which can then be turned on or left off for each specific virtual host.  This is the equivilent of blocking all connections on a firewall, and then opening up only the ones you want, which is a lot safer than leaving everything open globally, and assuming your programmers will never overlook a possible security hole.

Azureash
27-Jan-2003 04:34


Another way to hide your .php extensions is to use the Apache ForceType directive (which is often referred to as pretty URLs.)  Basically you force Apache to parse a file as PHP that matches the trailing directory name in your URL.



For example, place this directive in your Apache httpd.conf file:

<Location /home>

     ForceType application/x-httpd-php

</Location>



and create a php file name "home" in your doc root.  This file should not have a .php extension, and can be a php template file.  Combined with a function to strip out URL parameters, this can create a new templating system, which can effectively hide your file extensions.



In this example,

http://www.foo.com/home/bar.html



would actually use the home script we created, and then the "bar.html" could be used to specify content to include.

Kevin Vincent
23-Jan-2003 05:43


Just a thought but if you have changed the extensions that php interprets I would assume you've also changed header.php and footer.php files to the new extension.



EG:



index.php, somefile.php, header.php, footer.php...



Change the Apache directive so PHP interprets .kev files and rename your files:



index.kev, somefile.kev, header.kev, footer.kev



If you leave header and footer as PHP files then it won't understand how to interpret them.

sth at panix dot com
04-Aug-2002 12:45


The flipside to this is, if you're running a version of 

PHP/Apache which is not known to have exploitable bugs (usually the latest stable version at the time), and an attacker sees this, they may give up before even trying. If they don't, they may continue to attempt their exploit(s).



It really depends on the type of attacker. The educated, security advisory reading attacker vs. script kiddie on the street.



If you're keeping up on patches, version exposition should not be a problem for you.

m1tk4 at hotmail dot com
22-Jul-2002 05:53


I usually do:



<code>

RewriteEngine on<br>

RewriteOptions inherit<br>

RewriteRule (.*)\.htm[l]?(.*) $1.php$2 [nocase]<br>

</code>



in .htaccess. You'll need mod_rewrite installed for this .

yasuo_ohgaki at yahoo dot com
26-Jan-2002 03:59


To hide PHP, you need following php.ini settings



expose_php=Off 

display_errors=Off



and in httpd.conf



ServerSignature Off

(min works, but I prefer off)

istvan dot takacsNOSPAM at hungax dot com
30-Dec-2001 09:42


And use the


ServerTokens min


directive in your httpd.conf to hide installed PHP modules in apache.