Security - Keeping It Off The Web

The topic of website security is seldom brought up among non-programmers andthose who may not be technically inclined, yet if you operate a website, it isan issue of substantial concern to you.

Addressed in this article is a nearly universal problem, it affects almostevery single PHP or CGI script I've ever seen. We won't delve into thetechnical issues too far, this is intended for the web site owner, someone whomight install the occasional PHP file or CGI script. I will assume you are nota software developer.

A general rule I like to follow when installing php scripts or web applicationsis this: If it doesn't need to be on the web, it shouldn't be there. This isobvious, but it has implications that are not always clear.

What we are mainly referring to is configuration and to a lesser extent,program libraries and source code. It may also apply to files and otherresources that are controlled through a script interface. An example of thiswould be scripts that charge money for downloading files or set up newsletters.

Lets start with an example, we'll call it program.php. In our example,program.php is a database application using mysql to store information.

For our script to do it's job, it will need access to your mysql password anduser-name. It may also need access to many other program files and so-forth.

During installation, a control panel probably asked for your mysql credentials,it may even have asked you to change the file permissions on a configurationfile of some sort. You've probably been through this type of install process at one time or another.

What it will do next, is write your database password and other privateinformation to a configuration file. This usually happens without yourknowledge, it is also where our problems begin.

Most people don't catch this right away, if the configuration file is inthe same directory (or sub-directory) it is web accessible. Quite often it is a php file, usually with write permissions turned on.

The extension .php does afford some degree of protection, under normalcircumstances these files aren't sent to a visitors browser but it is stillunsafe.

If someone makes a slight mistake in the configuration or .htaccess file, itwill dump the actual contents of "conf.php" to the users web browser, completewith your database password and other private information.

As anyone who has been around web servers very long can tell you, this isa common occurrence. I've personally seen it happen on several occasions.

Furthermore, many other web editing tools need to create backup files,resulting in something like config.php.BAK or perhaps config.php.tmp.

We now have a file ripe for hackers and other would-be intruders to gain accessto your mysql database passwords as well as any other private informationkept there.

What is most alarming is that almost every single off the shelf web basedprogram exhibits this very problem in some form or another.

You may ask yourself why a competent software designer would do such a thing? Why is it so common?

The answer is simplicity and market value. Customers demand software that iseasy to install. It is actually done this way for your convenience.

Scripts that store everything in one directory make it easy for you, thewebsite owner, to install and manage. Web software customers have come to demand this sort of thing.

Most software designers are aware of this problem, this is why they oftenchoose to write configuration into a .php file, it gives you some protection atthe expense of introducing other potentially security problems we won't coverhere.

While java servlet technology provides WEB-INF/ (a secure place to store thistype of information) most PHP or CGI environments do not offer such anenvironment.

Furthermore some web servers use something called "safe mode" which is amisguided attempt to make PHP "secure", operating in this mode forces a softwaredeveloper to write insecure programs in the manner I've just outlined.

For those of you who have inspected your website, good job! you've probablydiscovered you do have this problem. The next question is "What can be done"?

The correct approach is to relocate your configuration files (and any otherinformation that shouldn't be web accessible) to a place safely outside yourdocument root (sometimes called your "web folder") after you have done this,you shouldn't be able to access the files with a web browser, not even witha password.

I generally like to use the HOME directory, but it doesn't matter as long asit's safely kept well away from the prying eyes of would-be hackers.

With many scripts, this is not very practical, particularly if you have alreadyinstalled them. At this point, damage control may be your only option.

If you're using apache, you can give yourself some added protection in the formof an .htaccess file, this is still not not secure, but it's certainly betterthan nothing at all. In "safe" mode, this may be your only option.

There are also things you can do via the language itself, but I won't coverthem here.

After you have done this, it is important to make a note to yourself about it.When backing up your website, you will need to include not only the web pages,but these other files that you now have safely tucked outside your webdirectory.

If you are unable to solve the problem, (for example the web script won't allowyou to locate these files elsewhere) Simply being aware of it can go a long waytoward protecting your website from future attackers. Now that you know, you can keep an eye out for any backup files that may have been created by other tools.

Try not to be too tough on whoever wrote the program, chances are they choseto do it this way for the convenience of their users. I can attest from firsthand experience, if you don't store configuration data this way, customerscan become annoyed and rarely understand your reasoning.