What are the best practices for avoid xss attacks in a PHP site

Posted by rikh on Stack Overflow See other posts from Stack Overflow or by rikh
Published on 2008-09-16T11:20:02Z Indexed on 2010/04/18 2:03 UTC
Read the original article Hit count: 439

Filed under:

php

|

xss

|

best-practices

|

security

I have PHP configured so that magic quotes are on and register globals are off.

I do my best to always call htmlentities() for anything I am outputing that is derived from user input.

I also occasionally seach my database for common things used in xss attached such as...

<script

What else should I be doing and how can I make sure that the things I am trying to do are always done.

© Stack Overflow or respective owner

Related posts about php

Magento, NGINX, PHP-FPM, APC, MEMCACHED, 16gb Ram CentOS, Spiking PHP-FPM to 100% CPU

as seen on Server Fault - Search for 'Server Fault'
I have been trying to resolve my issue of spiking cpu caused by php-fpm processes. I've reduced the php-fpm config settings to: pm = ondemand pm.max_children = 12 pm.start_servers = 2 pm.min_spare_servers = 2 pm.max_spare_servers = 10 pm.max_requests = 500 php_admin_value[memory_limit] = 128M Problem… >>> More
PHP Pear Installation on CentOS

as seen on Server Fault - Search for 'Server Fault'
[root@ip ~]# yum install php-pear* Reducing CentOS-5 Testing to included packages only Finished Setting up Install Process Package 1:php-pear-1.8.1-2.el5.centos.noarch already installed and latest versio … >>> More
Apache configurations for php "AddType text/html php" or "AddType application/x-httpd-php php .php"

as seen on Server Fault - Search for 'Server Fault'
I am taking over an application server and discover that it contain the following settings: AddType text/html php Although it works, but my understanding is that it should set as following: AddType application/x-httpd-php php .php What are the key differences between the two settings?… >>> More
mod_rewrite settings causes server to throw HTTP 500 errors instead of 404

as seen on Server Fault - Search for 'Server Fault'
Hello. I have a server with VBulletin forum (working under Apache 2.2, CentOS). The default settings for it in .htaccess are as follows: RewriteEngine on RewriteCond %{HTTP_HOST} ^gsmforum\.ru RewriteRule (.*) http://www.gsmforum.ru/$1 [R=301,L] # If you are having problems or are using VirtualDocumentRoot… >>> More
Problems installing Memcache (PECL extension)

as seen on Server Fault - Search for 'Server Fault'
I have installed memcached fine, and now I will need to install PECL extension memcache. Im running RedHat x86_64 es5. The installation gives me this: downloading memcache-2.2.6.tgz ... Starting to download memcache-2.2.6.tgz (35,957 bytes) ..........done: 35,957 bytes 11 source files, building running:… >>> More

Related posts about xss

XSS filtering function in PHP

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, Does anyone know of a good function out there for filtering generic input from forms? Zend_Filter_input seems to require prior knowledge of the contents of the input and I'm concerned that using something like HTML Purifier will have a big performance impact. What about something like : http://snipplr… >>> More
A way around XSS?

as seen on Stack Overflow - Search for 'Stack Overflow'
In my page I have an script reference to the autoHeight.js file below. I also have an iframe that I want to resize using this code. In firebug I get this error Error: Permission denied for <http://www.siena.edu> to get property HTMLDocument.body from <https://siteframework.siena.edu>… >>> More
Why isn't ValidateRequest="true" enough for XSS prevention?

as seen on Stack Overflow - Search for 'Stack Overflow'
In the notes for Step 1 in the "How To: Prevent Cross-Site Scripting in ASP.NET" it is stated that you should "not rely on ASP.NET request validation. Treat it as an extra precautionary measure in addition to your own input validation." Why isn't it enough? >>> More
How Google Wave cannot be XSS injected by a widget

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, If you've used google wave you probabely seen that you can insert widgets that are made by third parties without approval. the Question is : How this widgets can't inject XSS or steal the cookies, Are the widgets loaded in an <iframe> ? if yes, then how they can't redirect google wave… >>> More
Why Google Wave & iGoogle cannot be XSS injected by a widget

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, If you've used google wave or iGoogle you probabely seen that you can insert widgets that are made by third parties without approval. the Question is : How this widgets can't inject XSS or steal the cookies, Are the widgets loaded in an <iframe> ? if yes, then how they can't redirect… >>> More