Today, a friend reported that one of the apps I provide as a community service was down. Its WebCalendar component complained that magic_quotes_gpc was no longer enabled, which I quickly confirmed by dropping in a phpinfo() call. The remedy was also quick and easy: add a local php.ini with:
magic_quotes_gpc = On
This automatically adds slashes to escape quotes and other characters in GET, POST, and Cookie strings (hence “gpc”). The PHP code then removes these via stripslashes and similar techniques.
Magic_quotes_gpc is no longer considered a good way to guard against SQL injection attacks, so the PHP Security Consortium and others now recommend against it. I suspect this is why my hosting service changed their global setting to off, but security-wise, that was a step in the wrong direction.
Many PHP apps that support magic quotes are coded to work even if it’s turned off, and the get_magic_quotes_gpc() ? stripslashes template for doing this is seemingly everywhere. Fortunately, WebCalendar checks for this, but many apps don’t. Disabling magic quotes was probably done to force apps to change, but it’s more likely apps will continue to work and developers and admins won’t realize that they are suddenly far more susceptible to injection attacks. A better approach would have been to just let it die with the 5.3 upgrade.