Build a fortress that is impregnable: a solid shield against PHP cross-site request forgery (CSRF)

php editor Yuzai will show you how to build a strong fortress and build an airtight line of defense to resist cross-site request forgery (CSRF) attacks. This article will introduce the principles and harms of CSRF attacks in detail, and share some effective preventive measures to help developers strengthen security protection when writing PHP applications to ensure the security of user data and systems. Let us learn together how to build a solid shield and protect the security of the online world!

Cross-site request forgery (CSRF) is a common WEB Security vulnerability that allows an attacker to perform malicious actions as a victim without authorization. . CSRF attacks are usually initiated by inducing users to click on malicious links or open malicious websites. The attacker takes advantage of the user's trust and prompts the victim to unknowingly access the attacker's server and carry the victim's identity. Verify information and send attacker-crafted requests to the victim's web application. Attackers can use these requests to perform various malicious operations, such as modifying or deleting sensitive data, conducting fraudulent transactions, sending spam, etc.

2. The dangers of cross-site request forgery (CSRF)

The harm of CSRF attacks is huge, and it may lead to the following serious consequences:

• Steal sensitive information: Attackers can use CSRF attacks to steal victims' sensitive information, such as usernames, passwords, credit card numbers, social security numbers, etc.
• Perform malicious operations: Attackers can use CSRF attacks to perform various malicious operations, such as modifying or deleting the victim's personal information, conducting fraudulent transactions, sending spam, etc.
• Damage a website’s reputation: CSRF attacks can damage a website’s reputation, causing users to lose trust in the website.

3. Measures to prevent CSRF attacks

In order to prevent CSRF attacks, the following measures can be taken:

1. Verify the request source: When processing a user request, verify whether the request source is legitimate. You can use one of the following methods:

• Origin request header: Check the Origin request header to ensure that the request comes from a legitimate source.
• Referer request header: Check the Referer request header to ensure that the request comes from the page the user is currently on.
• SameSite Cookie: Set SameSite Cookie to prevent cross-site request forgery attacks.

2. Use a random number token: Generate a unique random number token in each user session and pass the token as a parameter to the server in each request. The server verifies the validity of the token when processing the request and rejects the request if the token is invalid.
3. Implement strict cross-domain restrictions: Implement strict cross-domain restrictions on the website and prohibit requests from other domains from accessing the website's sensitive resources.
4. Strictly check user input: Strictly check user input to prevent user input from containing malicious code or scripts.
5. Use security frameworks and libraries: Use security frameworks and libraries, such as Symfony, Laravel, etc. These frameworks and libraries usually already include CSRF protection functions.

4. Demonstration code to prevent CSRF attacks in PHP

<?PHP
// 从表单中获取数据
$username = $_POST["username"];
$passWord = $_POST["password"];

// 验证随机数令牌
if (!isset($_POST["token"]) || $_POST["token"] !== $_SESSioN["token"]) {
// 令牌无效，拒绝请求
die("Invalid token");
}

// 验证用户身份
if ($username === "admin" && $password === "password") {
// 登录成功
echo "Login success";
} else {
// 登录失败
echo "Login failed";
}
?>

5. Conclusion

CSRF attacks are a common web security vulnerability that can have serious security consequences. By taking effective preventive measures, such as verifying the source of requests, using random number tokens, implementing strict cross-domain restrictions, strictly checking user input, and using security frameworks and libraries, you can effectively prevent CSRF attacks and ensure that web applications safety.

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