Why is register globals bad in php

You may want to read about the very useful ternary operator. If you found this article helpful, please click the "thumb's up" button below. Doing so lets the E-E community know what is valuable for E-E members and helps provide direction for future articles. If you have questions or comments, please add them. Ask a related question. Commented: Ray I have a somewhat silly question for you.

Is it a bad practice to initialize all of your variables with PHP? I think it comes from VB coding. Most Valuable Expert This award recognizes tech experts who passionately share their knowledge with the community and go the extra mile with helpful contributions. Author of the Year This award recognizes authors who provide insightful, original works that bring value and awareness to the tech community.

Author Commented: I recommend that you initialize variables. Not all of my code does this but it is a really great idea. PHP does not require it. Quel Fromage. Get Access. Get access with a 7-day free trial. Try a week for free to see if you belong. Experts Exchange Take hold of your future. All rights reserved. Web application security is a young and evolving discipline.

This book teaches best practices that are theoretically sound, so that you can sleep at night instead of worrying about the new attacks and techniques that are constantly being developed by those with malicious intentions.

However, it is wise to keep yourself informed of new advances in the field, and there are a few resources that can help:. This chapter provides the foundation for the rest of the book. It focuses on teaching you the principles and practices that are prerequisities for the lessons that follow. PHP has many unique features that make it very well-suited for web development.

Common tasks that are cumbersome in other languages are a cinch in PHP, and this has both advantages and disadvantages. If you remember writing CGI applications in C in your early days of web application development, you know how tedious form processing can be.

This makes writing PHP applications very easy and convenient, but it also poses a security risk. Alone, it does not create a security vulnerability—a developer must make a mistake.

However, the detailed information that PHP provides can be displayed to a malicious attacker, and this is undesirable. It is important to make sure that this information is never shown to the general public. All error-reporting behavior can be modified at any level, so if you are on a shared host or are otherwise unable to make changes to files such as php. For example, you can create a function that handles only warnings:. PHP 5 also provides support for exceptions. You can adopt many principles to develop more secure applications.

I have chosen a small, focused list of the principles that I consider to be most important to a PHP developer. These principles are intentionally abstract and theoretical in nature. Their purpose is to provide a broad perspective that can guide you as you focus on the details. Consider them your road map. Defense in Depth is a well-known principle among security professionals. It describes the fact that there is value in redundant safeguards, and history supports this.

The principle of Defense in Depth extends beyond programming. A skydiver who has ever needed to use a reserve canopy can attest to the value in having a redundant safeguard.

After all, the main canopy is never meant to fail. A redundant safeguard can potentially save the day when the primary safeguard fails. In the context of programming, adhering to Defense in Depth requires that you always have a backup plan. If a particular safeguard fails, there should be another to offer some protection. For example, it is a good practice to prompt a user to reauthenticate before performing some important action, even if there are no known flaws in your authentication logic.

Although Defense in Depth is a sound principle, be aware that security safeguards become more expensive and less valuable as they are accrued. I used to drive a car that had a valet key.

This key worked only in the ignition, so it could not be used to unlock the console, the trunk, or even the doors—it could be used only to start the car. I could give this key to someone parking my car or simply leave it in the ignition , and I was assured that the key could be used for no other purpose. It makes sense to give a key to a parking attendant that cannot be used to open the console or trunk. After all, you might want to lock your valuables in these locations.

Of course, this is because my perspective was that of revoking privilege—I was considering why the parking attendant should be denied the privilege of opening the doors. This is not a good perspective to take when developing web applications.

Instead, you should consider why a particular privilege is necessary, and provide all entities with the least amount of privilege required for them to fulfill their respective responsibilities. One reason why the valet key cannot open the doors is that the key can be copied. Such a copy can be used to steal the car at a later date. This situation might seem unlikely it is , but this illustrates why granting an unnecessary privilege can increase your risk, even if the increase is slight.

Minimizing risk is a key component of secure application development. It is not necessary that you be able to think of all of the ways that a particular privilege can be exploited. In fact, it is practically impossible for you to be able to predict the actions of every potential attacker. What is important is that you grant only least privilege.

This minimizes risk and increases security. Complication breeds mistakes, and mistakes can create security vulnerabilities. This simple truth is why simplicity is such an important characteristic of a secure application. Unnecessary complexity is as bad as an unnecessary risk. Contrast this with the following:.

The primary remote sources are HTTP clients browsers and databases. If you properly track data, you should be able to identify when data is exposed. The primary source of exposure is the Internet, and you want to be particularly mindful of data that is exposed over the Internet because it is a very public network. However, the exposure of sensitive data should be minimized as much as possible. For example, if a user enters payment information, you should use SSL to protect the credit card information as it travels from the client to your server.

If you display this credit card number on a verification page, you are actually sending it back to the client, so this page should also be protected with SSL. In this particular scenario, displaying the credit card number to the user increases its exposure. SSL does mitigate the risk, but a better approach is to eliminate the exposure altogether by displaying only the last four digits or any similar approach.

This is probably the most simply and painless variant. But this will be more error prone. Using the IDE will probably give you better results with less effort.

So there's definitely some extra work being done there but enough to detriment the speed of the whole app? I really doubt it Not unless you're on really old hardware or doing it a lot.

For simple apps, just making sure you've only included it once should suffice but if you're still getting redefine errors, you could something like this:.