Q. I run a small Apache based webserver for my personal use and it is shared with friends and family. However, most script kiddie try to exploit php application such as wordpress using exec() , passthru() , shell_exec() , system() etc functions. How do I disable these functions to improve my php script security?
A. PHP has a lot of functions which can be used to crack your server if not used properly. You can set list of functions in php.ini using disable_functions directive. This directive allows you to disable certain functions for security reasons. It takes on a comma-delimited list of function names. disable_functions is not affected by Safe Mode. This directive must be set in php.ini For example, you cannot set this in httpd.conf.
Open php.ini file:
# vi /etc/php.ini
Find disable_functions and set new list as follows:
disable_functions =exec,passthru,shell_exec,system,proc_open,popen,curl_exec,curl_multi_exec,parse_ini_file,show_source
Save and close the file. Restart httpd:
# service httpd restart
{ 3 comments… read them below or add one }
This is not enought because you can always use “`” that will bypass these limitation.
I guess if you really need those functions, you can overwrite the configuration using ini_set function in your script to enable them for a particular site.
Davide you are wrong “`” using shell_exec function so if we disable shell_exec then “`” will be disabled too