How to correctly use defensive injection functions in PHP language development?

With the rapid development of the Internet, network security issues have become increasingly prominent. As a scripting language widely used in website and application development, injection vulnerabilities in PHP have always been a popular target for attackers. Therefore, taking effective measures to defend against injection attacks has become one of the essential skills for PHP developers. This article will detail how to correctly use defensive injection functions in PHP language development.

1. The harm of injection attacks

Injection attacks refer to attackers embedding malicious code into the input parameters of a website or application to perform operations harmful to it. This attack method includes SQL injection, OS command injection, XPath injection, etc. A successful injection attack will not only destroy the basic functions of the website or application, but may also lead to data leaks, system crashes, and in severe cases, user information may be stolen and identities may be stolen, causing great losses to users, businesses, and society. .

2. Measures to defend against injection attacks

In order to prevent injection attacks, PHP provides multiple built-in functions for checking, filtering, and escaping user input data. These functions cover different types of injection attacks. Let’s take a look at some common measures to defend against injection attacks.

1. Avoid using vulnerable functions such as eval() and preg_replace(): Functions such as eval() and preg_replace() can parse strings as executable code and are vulnerable to injection attacks. Therefore, it is best to avoid using these functions or switch to safer functions.

2. Use mysqli or PDO instead of the mysql function: The mysql_real_escape_string() function in the MySQL function cannot completely defend against injection attacks and is easily cracked. Therefore, it is better to use mysqli or PDO instead of mysql functions. mysqli and PDO provide more security features such as prepared statements and parameterized queries.

3. Use the filter_input() function to filter user input: User input data is one of the main entrances for injection attacks. Using the filter_input() function can effectively help us filter and verify user input data to avoid injection attacks.

4. Use the htmlspecialchars() function to escape special characters: In order to prevent cross-site scripting attacks (XSS), you should use the htmlspecialchars() function to escape special characters in input and output data, such as <, > ," and other symbols, making them equivalent HTML entities, thereby protecting the information security of the system.

5. Use prepared statements to operate the database: prepared statements are a special query method that can combine parameters with SQL query statements are separated to prevent SQL injection attacks. Using prepared statements to operate the database can effectively reduce injection vulnerabilities.

3. Commonly used defense injection attack functions

In PHP, Commonly used defense injection attack functions include:

1. mysql_real_escape_string(): This function provides a way to escape strings for databases such as MySQL to avoid SQL injection.

2. mysqli_real_escape_string() : Similar to mysql_real_escape_string(), but provides an escape method for new MySQL functions.

3. PDO::quote(): The quote() method places the parameters of the SQL statement in quotes to prevent SQL Injection.

4. filter_input(): The filter_input function is used to avoid malicious input. Multiple types of filters can be set, such as input filtering, escaping, and verification, to avoid injection attacks.

5. preg_replace(): The preg_replace function uses regular expressions to query and replace. However, since this function is similar to the eval() function, it should be used with caution.

4. Summary

Injection attack It is a problem that PHP developers cannot ignore. A simple vulnerability may cause the entire system to paralyze. How to defend against injection attacks has become one of the compulsory skills for PHP developers. During development, different defenses should be selected based on specific scenarios and application occasions. Strategy. This article summarizes common measures to defend against injection attacks and how to use functions to defend against injection attacks. I hope it will be helpful to PHP developers, and let us work together to build a more secure, stable, and reliable Internet world.

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