How to defend against command injection security vulnerabilities in PHP language development?

In the PHP language development process, command injection attack (Command Injection) is a common security vulnerability. Attackers construct malicious commands and inject them into web applications, causing the applications to execute malicious commands. Such attacks can lead to security issues such as confidential data leakage, system paralysis, and even remote command execution. This article will explore how to prevent command injection attacks in PHP language development.

1. Using preprocessors

In PHP development, when using database query statements, you should use parameterized query methods, that is, use preprocessors. This method can reduce the impact of user input on query statements. That is to say, users cannot successfully perform malicious operations by entering malicious SQL statements.

2. Filtering user input

Network transmission between the web application and the server is done through the HTTP protocol. The parameters in the request are transmitted in clear text. Therefore, filtering the request data on a front end can reduce the risk of command injection attacks. Specific methods include:

• For each input parameter, verify whether the parameter is legal, such as checking whether the data entered by the user conforms to the expected format.
• Filter special characters. There are some special characters in HTML and JavaScript that attackers can use to attack applications. Filtering special characters can prevent programs from being affected by attacks.
• Transcode user input data, especially spaces, to prevent SQL injection.

3. Avoid splicing commands directly

When splicing commands, it is easy to cause the risk of command injection attacks. Therefore, method calls, string concatenation, etc. should be avoided to generate statements such as SQL that receive commands. If disguised as a GET or POST request, PHP preset variables should be used to prevent attackers from tampering with these variables. Common preset variables include $_SERVER, $_SESSION, $_COOKIE, and $_ENV. These variables are automatically set by PHP at runtime, so their contents should not be modified directly in the application.

4. Use whitelist

Whitelist refers to the legal restrictions on the input data acceptable to the application. Limiting the scope of requirements is the simplest and most effective defense measure. Therefore, a whitelist should be used during development to limit user input data. The specific implementation can use regular expressions, arrays and other methods to judge and filter the accepted input data.

5. Limit the permissions used by the application

When developing, you need to limit the permissions required for the application to work, such as only giving PHP files minimum reading and writing Permissions to maintain machine and server security. Once an application that can access user data is attacked, serious security issues will arise. Therefore, it is recommended to set the directory where the user data is located to read access when deploying the application.

Conclusion

In PHP language development, command injection attacks are a serious security issue. Security control should be strengthened from multiple levels during development, such as using preprocessors, filtering user input, avoiding direct splicing of commands, using whitelists, and limiting the permissions used by applications. By implementing these security measures, you can avoid command injection attacks and improve the security and stability of your web applications.

The above is the detailed content of How to defend against command injection security vulnerabilities in PHP language development?. For more information, please follow other related articles on the PHP Chinese website!