OWASP Cheat Sheet Series: PHP Configuration Cheat Sheet

# PHP Configuration Cheat Sheet

## Introduction

This page is meant to help those configuring PHP and the web server it is running on to be very secure.

Below you will find information on the proper settings for the `php.ini` file and instructions on configuring Apache, Nginx, and Caddy web servers.

For general PHP codebase security please refer to the two following great guides:

- [Paragonie's 2018 PHP Security Guide](https://paragonie.com/blog/2017/12/2018-guide-building-secure-php-software)
- [Awesome PHP Security](https://github.com/guardrailsio/awesome-php-security)

## PHP Configuration and Deployment

### php.ini

Some of following settings need to be adapted to your system, in particular `session.save_path`, `session.cookie_path` (e.g. `/var/www/mysite`), and `session.cookie_domain` (e.g. `ExampleSite.com`).

You should be running a [supported version of PHP](https://www.php.net/supported-versions.php) (as of this writing, 8.1 is the oldest version receiving security support from PHP, though distribution vendors often provide extended support). Review the [core `php.ini` directives](https://www.php.net/manual/ini.core.php) in the PHP Manual for a complete reference on every value in the `php.ini` configuration file.

You can find a copy of the following values in a [ready-to-go `php.ini` file here](https://github.com/danehrlich1/very-secure-php-ini).

#### PHP error handling

```text
expose_php              = Off
error_reporting         = E_ALL
display_errors          = Off
display_startup_errors  = Off
log_errors              = On
error_log               = /valid_path/PHP-logs/php_error.log
ignore_repeated_errors  = Off
```

Keep in mind that you need to have `display_errors` to `Off` on a production server and it's a good idea to frequently notice the logs.

#### PHP general settings

```text
doc_root                = /path/DocumentRoot/PHP-scripts/
open_basedir            = /path/DocumentRoot/PHP-scripts/
include_path            = /path/PHP-pear/
extension_dir           = /path/PHP-extensions/
mime_magic.magicfile    = /path/PHP-magic.mime
allow_url_fopen         = Off
allow_url_include       = Off
variables_order         = "GPCS"
allow_webdav_methods    = Off
session.gc_maxlifetime  = 600
```

`allow_url_*` prevents [LFI](https://www.acunetix.com/blog/articles/local-file-inclusion-lfi/)s to be easily escalated to [RFI](https://www.acunetix.com/blog/articles/remote-file-inclusion-rfi/)s.

#### PHP file upload handling

```text
file_uploads            = On
upload_tmp_dir          = /path/PHP-uploads/
upload_max_filesize     = 2M
max_file_uploads        = 2
```

If your application is not using file uploads, and say the only data the user will enter / upload is forms that do not require any document attachments, `file_uploads` should be turned `Off`.

#### PHP executable handling

```text
enable_dl               = Off
disable_functions       = system, exec, shell_exec, passthru, phpinfo, show_source, highlight_file, popen, proc_open, fopen_with_path, dbmopen, dbase_open, putenv, move_uploaded_file, chdir, mkdir, rmdir, chmod, rename, filepro, filepro_rowcount, filepro_retrieve, posix_mkfifo
disable_classes         =
```

These are dangerous PHP functions. You should disable all that you don't use.

#### PHP session handling

Session settings are some of the MOST important values to concentrate on in configuring. It is a good practice to change `session.name` to something new.

```text
 session.save_path                = /path/PHP-session/
 session.name                     = myPHPSESSID
 session.auto_start               = Off
 session.use_trans_sid            = 0
 session.cookie_domain            = full.qualified.domain.name
 #session.cookie_path             = /application/path/
 session.use_strict_mode          = 1
 session.use_cookies              = 1
 session.use_only_cookies         = 1
 session.cookie_lifetime          = 14400 # 4 hours
 session.cookie_secure            = 1
 session.cookie_httponly          = 1
 session.cookie_samesite          = Strict
 session.cache_expire             = 30
 session.sid_length               = 256
 session.sid_bits_per_character   = 6
```

#### Some more security paranoid checks

```text
session.referer_check   = /application/path
memory_limit            = 50M
post_max_size           = 20M
max_execution_time      = 60
report_memleaks         = On
html_errors             = Off
zend.exception_ignore_args = On
```

### Snuffleupagus

[Snuffleupagus](https://snuffleupagus.readthedocs.io) is the spiritual
descendent of Suhosin for PHP 7 and onwards, with [modern
features](https://snuffleupagus.readthedocs.io/features.html). It's considered
stable, and is usable in production.