PHP programming practices to prevent cross-site request forgery attacks

PHP programming practices to prevent cross-site request forgery attacks

With the development of the Internet, Web applications are becoming more and more popular. However, web applications also face a wide range of network attacks, one of which is the Cross-Site Request Forgery (CSRF) attack. In this article, we will explore how to use PHP programming techniques to prevent CSRF attacks and provide relevant code examples.

The principle of a CSRF attack is that the attacker uses the user's logged-in identity to send requests that can perform malicious operations to the target website without the user's knowledge. The purpose of this is to achieve the attacker's illegal purpose, such as making changes to user accounts, deleting sensitive information, etc.

In order to prevent CSRF attacks, we can adopt the following programming practices:

1. Verify the source of the request: First, add a hidden field in the form of the website, which contains a random The generated token. When the user submits the form, the server checks to see if the token exists and is valid. This way, if the source of the request is untrustworthy, the server will refuse to execute the request. The following is a sample code that implements this feature:

<?php
// 生成 CSRF 令牌
$token = bin2hex(random_bytes(32));
$_SESSION['csrf_token'] = $token;

// 在表单中添加隐藏域
echo '<input type="hidden" name="csrf_token" value="' . $token . '">';

// 验证 CSRF 令牌
if ($_POST['csrf_token'] !== $_SESSION['csrf_token']) {
    die('Invalid CSRF token');
}
// 继续处理请求
// ...
?>

2. Set the secure SameSite Cookie attribute: In order to prevent cross-site requests, we can set the Cookie's SameSite attribute to "strict" or " lax". This ensures that the cookie can only be sent in the same context as its originating site. The following is a sample code for setting SameSite properties:

<?php
// 设置 Cookie 的 SameSite 属性
session_set_cookie_params(['samesite' => 'strict']);
session_start();
?>

3. Add a verification code mechanism: In addition to the above methods, we can also add a verification code mechanism to increase security. When a user performs a sensitive operation (such as changing a password), the user is required to enter a verification code to ensure that the user is the real initiator of the operation.

In order to protect web applications from CSRF attacks, we must take a series of measures, including verifying the source of the request, setting secure SameSite Cookie attributes and using a verification code mechanism. These programming practices can greatly reduce the risk of CSRF attacks and improve the security of web applications.

However, it is worth noting that these methods are not absolutely safe. Hackers are also constantly developing new attack techniques. Therefore, we need to pay close attention to network security trends and constantly update and improve our protection strategies.

In short, preventing CSRF attacks programmatically is an important part of protecting the security of web applications. By verifying the source of the request, setting the secure SameSite Cookie attribute, and adding a verification code mechanism, we can greatly reduce the risk of CSRF attacks. I hope this article can help readers understand and apply these protective measures.

Reference:

• OWASP CSRF Prevention Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html
• PHP session management : https://www.php.net/manual/en/features.sessions.php

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