Security measures for PHP and CGI: How to prevent your website from being hacked

Security protection measures for PHP and CGI: How to prevent websites from being attacked by hackers

With the popularity and development of the Internet, website security issues have attracted more and more attention. PHP and CGI, as commonly used web programming languages, also need to strengthen security measures to prevent hacker attacks. This article will introduce some security protection measures for PHP and CGI and provide corresponding code examples.

1. Verify user input

User input is the most vulnerable part to hackers. The risk of being attacked can be greatly reduced by validating and filtering user input. Here are some common user input validation code examples.

1.1. For string input, you can use the filter function to filter user input to prevent common injection attacks.
Sample code:

$input = $_GET['input'];
$filteredInput = filter_var($input, FILTER_SANITIZE_STRING);

1.2. For numeric input, you can use the is_numeric() function to verify to ensure that the input is a valid number.
Sample code:

$input = $_GET['input'];
if(!is_numeric($input)){
    die("Invalid input");
}

1.3. For inputs in specific formats such as email addresses and URLs, regular expressions can be used for verification.
Sample code:

$email = $_GET['email'];
if(!preg_match("/^w+([.-]?w+)*@w+([.-]?w+)*(.w{2,3})+$/", $email)){
    die("Invalid email");
}

2. Password security

Password is an important protection for user accounts. It is very necessary to take some measures to improve the security of passwords.

2.1. Use the password hash function

When storing user passwords, you should use a hash function to encrypt and store the password to protect the security of the user password.
Sample code:

$password = $_POST['password'];
$hashedPassword = password_hash($password, PASSWORD_DEFAULT);
// 存储 $hashedPassword 到数据库

2.2. Password strength requirements

Set password strength requirements, such as password length, complexity, etc., to remind users to set secure passwords.
Sample code:

$password = $_POST['password'];
if(strlen($password) < 8){
    die("密码长度至少为8位");
}

3. File upload

The file upload function is one of the common functions in the website, but it is also a potential security risk. Here are some common security measures.

3.1. File type verification

Verify the legality of the file by checking the file extension or MIME type to avoid the upload of some malicious files.
Sample code:

$file = $_FILES['file'];
$allowedExtensions = ['jpg', 'png', 'gif'];
$allowedMimeTypes = ['image/jpeg', 'image/png', 'image/gif'];
if(!in_array(pathinfo($file['name'], PATHINFO_EXTENSION), $allowedExtensions) 
    || !in_array($file['type'], $allowedMimeTypes)){
    die("不允许上传该类型的文件");
}

3.2. File storage path security

Ensure that the path where the file is stored after uploading is safe to avoid security issues caused by file path leakage.
Sample code:

$savePath = '/path/to/save';
$filename = uniqid().'.jpg'; // 使用唯一的文件名
move_uploaded_file($_FILES['file']['tmp_name'], $savePath.'/'.$filename);

4. SQL injection protection

SQL injection attack is one of the common attack methods. The following are some common measures to prevent SQL injection.

4.1. Use prepared statements

Use prepared statements to bind parameters to prevent SQL injection attacks.
Sample code:

$username = $_POST['username'];
$password = $_POST['password'];
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username AND password = :password");
$stmt->execute([':username' => $username, ':password' => $password]);

4.2. Use parameterized query

Use parameterized query to pass user input as parameters to the database query statement to prevent SQL injection attacks.
Sample code:

$username = $_POST['username'];
$password = $_POST['password'];
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->execute([$username, $password]);

To sum up, through a series of security protection measures such as verifying user input, password security, file upload security, and preventing SQL injection attacks, the security of the website can be greatly improved. , reduce the risk of being attacked by hackers. During the development process, it is necessary to pay more attention to these aspects to protect the information security of the website and users.

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