This site is the archived OWASP Foundation Wiki and is no longer accepting Account Requests.
To view the new OWASP Foundation website, please visit https://owasp.org
Difference between revisions of "PHP Security Cheat Sheet"
Amna Khalid (talk | contribs) |
Amna Khalid (talk | contribs) |
||
| Line 3: | Line 3: | ||
This article is focused on providing PHP-specific guidance to securing web applications. | This article is focused on providing PHP-specific guidance to securing web applications. | ||
| − | = PHP | + | = PHP General Guidelines for Secure Web Applications = |
| − | == | + | == PHP Version == |
| + | Use '''PHP 5.3.8'''. Stable versions are always safer then the beta ones. | ||
| − | == Use | + | == Framework== |
| + | Use a framework like '''Zend''' or '''Symfony'''. Try not to re-write the code again and again. Also avoid dead codes. | ||
| − | == | + | == Directory== |
| + | Code with most of your code outside of the webroot. This is automatic for Symfony and Zend. Stick to these frameworks. | ||
| + | |||
| + | == Hashing Extension == | ||
| + | Not every PHP installation has a working '''mhash''' extension, so if you need to do hashing, check it before using it. Otherwise you can't do SHA-256 | ||
| + | |||
| + | == Cryptographic Extension == | ||
| + | Not every PHP installation has a working '''mcrypt''' extension, and without it you can't do AES. Do check if you need it. | ||
| + | |||
| + | == Authentication and Authorization == | ||
| + | There is no authentication or authorization classes in native PHP. Use '''ZF''' or '''Symfony''' instead. | ||
== Input nput validation == | == Input nput validation == | ||
Use $_dirty['foo'] = $_GET['foo'] and then $foo = validate_foo($dirty['foo']); | Use $_dirty['foo'] = $_GET['foo'] and then $foo = validate_foo($dirty['foo']); | ||
| − | == | + | == Use PDO or ORM == |
| + | Use PDO with prepared statements or an ORM like Doctrine | ||
| − | == | + | == Use PHP Unit and Jenkins == |
| + | When developing PHP code, make sure you develop with PHP Unit and Jenkins - see http://qualityassuranceinphpprojects.com/pages/tools.html for more details. | ||
| − | == | + | == Use Stefan Esser's Hardened PHP Patch == |
| + | Consider using Stefan Esser's Hardened PHP patch - http://www.hardened-php.net/suhosin/index.html | ||
| + | (not maintained now, but the concepts are very powerful) | ||
| − | == | + | == Avoid Global Variables== |
| + | In terms of secure coding with PHP, do not use globals unless absolutely necessary | ||
| + | Check your php.ini to ensure register_globals is off Do not run at all with this setting enabled It's extremely dangerous (register_globals has been disabled since 5.0 / 2006, but .... most PHP 4 code needs it, so many hosters have it turned on) | ||
| − | == | + | == Avoid Eval() == |
| + | It basically allows arbitrary PHP code execution, so do not evaluate user supplied input. and if you're not doing that, you can just use PHP directly. eval() is at least 10-100 times slower than native PHP | ||
| − | == | + | == Don't use $_REQUEST == |
| + | Instead of $_REQUEST- use $_GET or $_POST or $_SERVER | ||
| − | == | + | == Protection against RFI== |
| + | Ensure allow_url_fopen and allow_url_include are both disabled to protect against RFI But don't cause issues by using the pattern include $user_supplied_data or require "base" + $user_supplied_data - it's just unsafe as you can input /etc/passwd and PHP will try to include it | ||
| − | == | + | == Regexes (!)== |
| − | ( | + | Watch for executable regexes (!) |
| − | == | + | == Session Rotation == |
| − | + | Session rotation is very easy - just after authentication, plonk in session_regenerate_id() and you're done. | |
| − | == | + | == Be aware of PHP filters == |
| − | + | PHP filters can be tricky and complex. Be extra-conscious when using them. | |
| − | |||
| − | |||
| − | |||
| − | == | + | == Logging == |
| − | + | Set display_errors to 0, and set up logging to go to a file you control, or at least syslog. This is the most commonly neglected area of PHP configuration | |
| − | |||
| − | == | + | == Output encoding == |
| + | Output encoding is entirely up to you. Just do it, ESAPI for PHP is ready for this job. | ||
These are transparent to you and you need to know about them. php://input: takes input from the console gzip: takes compressed input and might bypass input validation http://au2.php.net/manual/en/filters.php | These are transparent to you and you need to know about them. php://input: takes input from the console gzip: takes compressed input and might bypass input validation http://au2.php.net/manual/en/filters.php | ||
Revision as of 05:15, 2 July 2012
- 1 DRAFT CHEAT SHEET - WORK IN PROGRESS
- 2 Introduction
- 3 PHP General Guidelines for Secure Web Applications
- 3.1 PHP Version
- 3.2 Framework
- 3.3 Directory
- 3.4 Hashing Extension
- 3.5 Cryptographic Extension
- 3.6 Authentication and Authorization
- 3.7 Input nput validation
- 3.8 Use PDO or ORM
- 3.9 Use PHP Unit and Jenkins
- 3.10 Use Stefan Esser's Hardened PHP Patch
- 3.11 Avoid Global Variables
- 3.12 Avoid Eval()
- 3.13 Don't use $_REQUEST
- 3.14 Protection against RFI
- 3.15 Regexes (!)
- 3.16 Session Rotation
- 3.17 Be aware of PHP filters
- 3.18 Logging
- 3.19 Output encoding
- 4 Related Cheat Sheets
- 5 Authors and Primary Editors
DRAFT CHEAT SHEET - WORK IN PROGRESS
Introduction
This article is focused on providing PHP-specific guidance to securing web applications.
PHP General Guidelines for Secure Web Applications
PHP Version
Use PHP 5.3.8. Stable versions are always safer then the beta ones.
Framework
Use a framework like Zend or Symfony. Try not to re-write the code again and again. Also avoid dead codes.
Directory
Code with most of your code outside of the webroot. This is automatic for Symfony and Zend. Stick to these frameworks.
Hashing Extension
Not every PHP installation has a working mhash extension, so if you need to do hashing, check it before using it. Otherwise you can't do SHA-256
Cryptographic Extension
Not every PHP installation has a working mcrypt extension, and without it you can't do AES. Do check if you need it.
Authentication and Authorization
There is no authentication or authorization classes in native PHP. Use ZF or Symfony instead.
Input nput validation
Use $_dirty['foo'] = $_GET['foo'] and then $foo = validate_foo($dirty['foo']);
Use PDO or ORM
Use PDO with prepared statements or an ORM like Doctrine
Use PHP Unit and Jenkins
When developing PHP code, make sure you develop with PHP Unit and Jenkins - see http://qualityassuranceinphpprojects.com/pages/tools.html for more details.
Use Stefan Esser's Hardened PHP Patch
Consider using Stefan Esser's Hardened PHP patch - http://www.hardened-php.net/suhosin/index.html (not maintained now, but the concepts are very powerful)
Avoid Global Variables
In terms of secure coding with PHP, do not use globals unless absolutely necessary Check your php.ini to ensure register_globals is off Do not run at all with this setting enabled It's extremely dangerous (register_globals has been disabled since 5.0 / 2006, but .... most PHP 4 code needs it, so many hosters have it turned on)
Avoid Eval()
It basically allows arbitrary PHP code execution, so do not evaluate user supplied input. and if you're not doing that, you can just use PHP directly. eval() is at least 10-100 times slower than native PHP
Don't use $_REQUEST
Instead of $_REQUEST- use $_GET or $_POST or $_SERVER
Protection against RFI
Ensure allow_url_fopen and allow_url_include are both disabled to protect against RFI But don't cause issues by using the pattern include $user_supplied_data or require "base" + $user_supplied_data - it's just unsafe as you can input /etc/passwd and PHP will try to include it
Regexes (!)
Watch for executable regexes (!)
Session Rotation
Session rotation is very easy - just after authentication, plonk in session_regenerate_id() and you're done.
Be aware of PHP filters
PHP filters can be tricky and complex. Be extra-conscious when using them.
Logging
Set display_errors to 0, and set up logging to go to a file you control, or at least syslog. This is the most commonly neglected area of PHP configuration
Output encoding
Output encoding is entirely up to you. Just do it, ESAPI for PHP is ready for this job.
These are transparent to you and you need to know about them. php://input: takes input from the console gzip: takes compressed input and might bypass input validation http://au2.php.net/manual/en/filters.php
Related Cheat Sheets
OWASP Cheat Sheets Project Homepage
Authors and Primary Editors
Andrew van der Stock
