Understand threats and take control: The art of PHP cross-site request forgery (CSRF) prevention

1. Principle of CSRF attack

php editor Zimo takes you to delve into the art of PHP cross-site request forgery (CSRF) prevention. CSRF attacks are one of the network security threats that perform malicious operations by disguising user requests. It is crucial to understand how to identify and prevent CSRF attacks. Let us learn together how to gain insight into potential threats, master global controls, and ensure website security.

2. How to prevent CSRF attacks

2.1 Using form tokens

Form tokens are a simple CSRF prevention measure. Include a randomly generated token in each form and validate the token on the server side. If the tokens do not match, the request is rejected.

2.2 Using sync token

Synchronization tokens are similar to form tokens, but they are more secure . A copy of the synchronization token is stored on both the client and server sides and compared on each request. If the tokens do not match, the request is rejected.

2.3 Using anti-CSRF token

Anti-CSRF tokens are a more advanced CSRF prevention measure. It uses the Referer field in the Http request header to verify the source of the request. If the Referer field does not match, the request is rejected.

2.4 Other precautions

In addition to the above methods, there are other measures to prevent CSRF attacks, including:

• Enable HTTP Strict Transport Security (HSTS) protocol
• Use Content Security Policy (CSP)
• Use Cross-Origin Resource Sharing (CORS)

3. Demo code

The following is a sample code that demonstrates how to use form tokens to prevent CSRF attacks:

<?PHP
session_start();

// 生成随机令牌
$token = bin2hex(random_bytes(16));

// 将令牌存储到会话中
$_SESSION["csrf_token"] = $token;
?>

<fORM action="process.php" method="post">
<input type="hidden" name="csrf_token" value="<?php echo $token; ?>">
<input type="text" name="username">
<input type="passWord" name="password">
<input type="submit" value="Login">
</form>

<?php
// 处理表单
if (isset($_POST["csrf_token"]) && $_POST["csrf_token"] === $_SESSION["csrf_token"]) {
// 表单已验证，可以安全地处理数据
} else {
// 表单未验证，拒绝请求
echo "Invalid CSRF token.";
}
?>

4 Conclusion

CSRF attacks are a serious threat, but they can be avoided by taking appropriate precautions. By using form tokens, sync tokens, anti-CSRF tokens, and other defenses, developers can protect their sites from CSRF attacks.

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