Security Tools • Vulnerability Analysis

pcc – PHP Secure Configuration Checker

November 8, 2017
3 Min Read

Check current PHP configuration for potential security flaws.
Simply access this file from your webserver or run on CLI.

Author
This software was written by Ben Fuhrmannek, SektionEins GmbH, in an effort to automate php.ini checks and spend more time on cheerful tasks.

Idea

  • one single file for easy distribution
  • simple tests for each security related ini entry
  • a few other tests – not too complicated though
  • compatible with PHP >= 5.4, or if possible >= 5.0
  • NO complicated/overengineered code, e.g. no classes/interfaces, test-frameworks, libraries, … -> It is supposed to be obvious on first glance – even for novices – how this tool works and what it does!
  • NO (or very few) dependencies

Usage / Installation

  • CLI: Simply call php phpconfigcheck.php. That’s it. Add -a to see hidden results as well, -h for HTML output and -j for JSON output.
  • WEB: Copy this script to any directory accessible by your webserver, e.g. your document root. See also ‘Safeguards’ below.
    The output in non-CLI mode is HTML by default. This behaviour can be changed by setting the environment variable PCC_OUTPUT_TYPE=text or PCC_OUTPUT_TYPE=json.
    Some test cases are hidden by default, specifically skipped, ok and unknown/untested. To show all results, use phpconfigcheck.php?showall=1. This does not apply to JSON output, which returns all results by default.
    To control the output format in WEB mode use phpconfigcheck.php?format=..., where the value of format maybe one of text, html or json. For example: phpconfigcheck.php?format=text. The format parameter takes precedence over PCC_OUTPUT_TYPE.

Safeguards
Most of the time it is a good idea to keep security related issues such as your PHP configuration to yourself. The following safeguards have been implemented:

  • mtime check: This script stops working in non-CLI mode after two days. Re-arming the check can be done by touch phpconfigcheck.php or by copying the script to your server again (e.g. via SCP). This check can be disabled by setting the environment variable: PCC_DISABLE_MTIME=1, e.g. SetEnv PCC_DISABLE_MTIME 1 in apache’s .htaccess.
  • source IP check: By default only localhost (127.0.0.1 and ::1) can access this script. Other hosts may be added by setting PCC_ALLOW_IP to a your IP address or a wildcard pattern, e.g. SetEnv PCC_ALLOW_IP 10.0.0.* in .htaccess. You may also choose to access your webserver via SSH Port forwarding, e.g. ssh -D or ssh -L.

Troubleshooting

  • disabled functions: This scripts needs a few functions to work properly, such as ini_get() and stat(). If one of these functions is blacklisted (or not whitelisted) then execution will fail or produce invalid output. In these cases it is possible to temporarily put Suhosin in simulation mode and omit disable_functions. To be on the safe side, relaxed security configuration can be done with .htaccess in a separate directory. Also, this script may be called from command line with your webserver’s configuration, e.g. php -n -c /etc/.../php.ini phpconfigcheck.php.
  • CLI: Older PHP versions don’t known about SAPI name ‘cli’ and use CGI style output even on cli. Workaround: PCC_OUTPUT_TYPE=text /opt/php/php-5.1.6/bin/php phpconfigcheck.php

WARNING
This tool will only support you setting up a secure PHP environment. Nothing else. Your setup, software or any related configuration may still be vulnerable, even if this tool’s output suggests otherwise.

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