How Secure Are PHP Session Variables for Storing User Authorization Levels?

The Security of PHP Session Variables

When implementing a secure login system, storing user authorization levels in PHP session variables may seem like a straightforward solution. However, it's essential to consider the potential security vulnerabilities associated with this approach.

Session variables are generally more secure than cookies, but they can still be compromised through server-level hacks. Therefore, it's crucial to implement additional security measures to mitigate these risks.

One recommended approach is IP checking. This involves verifying the user's IP address each time they access a page. However, this method has limitations, particularly for users behind intranet firewalls or those with dynamic IP addresses.

Alternatively, using a nonce (a per-page token) can enhance security. Each page checks if the current nonce matches the stored one. This helps prevent session stealing but may result in the dreaded "Clicking back will cause this page to break" error.

It's important to note that storing the user's session ID as a cookie can also expose them to security vulnerabilities. Therefore, cookies should not be used in conjunction with AJAX, as this combination can increase the risk of exploitation.

In conclusion, while PHP session variables offer greater security than cookies, they still require additional security measures such as IP checking or nonce-based validation to mitigate potential session stealing vulnerabilities.

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