How to prevent connection address escaping in php

In the field of web development, the PHP language is often used to write applications. It has excellent functions and easy-to-learn features. However, when using PHP to write web applications, we often need to process user input and prevent Possible security vulnerabilities. One of the common vulnerabilities is the connection address escape attack, if you want to protect your web application from such attacks, continue reading this article.

What is a connection address escape attack?

Connection address escape attacks, also known as HTTP parameter pollution vulnerabilities, refer to attackers controlling the behavior of web applications by tampering with parameter values ​​​​in URLs or form submissions, thereby achieving illegal access or performing inappropriate operations. the goal of.

For example, suppose we have a login page where users need to enter their username and password to log in. The submission address of the login form is http://www.example.com/login.php. When the user submits the form, the entered username and password will be encoded into the following GET parameter string:

http: //www.example.com/login.php?username=alice&password=123456

In this case, if an attacker wants to attack our application, they can change the server by adding other parameters The behavior of end-side processing of forms, for example:

http://www.example.com/login.php?username=alice&password=123456&isAdmin=true

Here, the attacker added a file named isAdmin parameter and set its value to true, which may grant administrator privileges to the web application, allowing it to perform many dangerous operations.

How to prevent connection address escape attacks?

In order to prevent connection address escaping attacks, we need to verify and filter the data submitted by users through forms or URLs to ensure that they do not affect our code execution. Here are several ways to prevent connection address escaping attacks:

1. Use the POST method instead of the GET method

The GET method passes form data as URL parameters, while the POST method Use the HTTP request body to pass data. The POST method is more secure than the GET method because the form data is not exposed in the URL and cannot be tampered with through the URL. So, if you can use the POST method to submit data, then use it!

2. Set default values ​​for all parameters

When the parameters received by the web page are empty, if they are not properly purified, it may lead to the so-called parameters of the attacker. Contamination attack. To prevent this attack, it is best to always set a default value for all parameters in your code.

For example, if we want to get a GET parameter named name, we can use the following code:

$name = !empty($_GET['name']) ? $_GET[' name'] : '';

This ensures that even if the "name" parameter is unset or empty, the code will continue to execute without causing errors or vulnerabilities.

3. Effective verification and filtering of input values

Any form data submitted by users should be verified and filtered to prevent unnecessary security threats. Here are some examples of input validation and filtering:

• Use PHP’s filter_var function to filter form data:

$username = filter_var($_POST['username'], FILTER_SANITIZE_STRING);

This will safely filter input values ​​in your code to ensure no malicious content exists.

• Prevent cross-site scripting attacks:

$comment = htmlspecialchars($_POST['comment']);

Use the htmlspecialchars() function Implement HTML escaping to prevent submitted comments from containing executable scripts, thereby protecting user security.

• Prevent SQL injection:

$username = mysqli_real_escape_string($connection, $_POST['username']);

Use the mysqli_real_escape_string() function Safely use user-entered strings as SQL queries and prevent SQL injection attacks.

Conclusion

Connection address escape attacks can cause serious security vulnerabilities in web applications. In order to avoid connection address escaping attacks, we need to validate and filter user input. This article introduces several effective preventive measures, hoping to help readers and strengthen the security of the website.

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