nodejs query database defense

Methods to Stop SQL Injection

With the rapid development of the Internet, data interaction between applications has become more and more frequent, the use of databases has become more and more important, and SQL injection attacks have become more and more rampant. . SQL injection means that hackers inject malicious code into the SQL statements of the application. When the data is passed into the database, the malicious code can be executed, causing the database data to be leaked or tampered with, greatly damaging the security of the system. In order to prevent SQL injection, Node.js also needs to take corresponding precautions when connecting to the database. This article will introduce several common prevention methods.

1.SQL parameterization

SQL parameterization is one of the more common methods to prevent SQL injection attacks. Its principle is to separate the parameters and values ​​​​in the SQL statement, encode the parameters, and separate them with special characters before sending to the database. In this way, even if a hacker attack injects malicious SQL statements, the database will process them as parameters instead of part of the SQL statement, thus improving the security of the database.

In Node.js, you can use parameterized query modules such as pg-promise or mysql2, etc. The example is as follows:

const pgp = require('pg-promise')();
const db = pgp('postgres://username:password@host:port/database');

const query = 'SELECT * FROM users WHERE name = ${name} AND age = ${age}';
const values = {name: 'Jack', age: 20};

db.any(query, values).then(data => {
  console.log(data);
}).catch(error => {
  console.log(error);
});

As a safe programming practice, it should be noted that Following the principle of least authorization, it's a good idea to verify user-supplied data before performing a retrieval/query. Ensure their type and scope, and whether users have access to the data associated with them.

2. Input validation and filtering

Input validation is an important step before data is sent to the server. Its goal is to ensure that the input data is well-formed and does not contain malicious code.

For example, before performing an insert/update operation on user-submitted data, you can check various aspects such as the type, range, and format of the input data to ensure that the input data exactly matches the expected data type.

In addition, it is also necessary to filter illegal characters in the data. These characters may contain HTML tags with SQL statement fragments or malicious JavaScript code. Node.js provides various modules, such as validator, etc., which can be used to filter and validate input data.

The following is an example of using validator:

const validator = require('validator');

const email = 'example.com';
if (!validator.isEmail(email)) {
  console.log('Invalid email');
}

3. Prevent splicing SQL statements

One of the most common scenarios of SQL injection attacks is to use string splicing SQL in the program statement, thereby embedding unsafe data. An attacker can corrupt the entire query or even obtain sensitive data by entering some code.

For example:

const query = 'SELECT * FROM users WHERE name = ' + name + ' AND age = ' + age;

This way of writing is very dangerous, because the attacker can submit a parameter value like "name = 'xxx; DROP TABLE users;'", and then the entire query will change Into:

SELECT * FROM users WHERE name = xxx; DROP TABLE users; AND age > 20;

This statement will delete the "users" table. In this case, our input validation and parameterized query are meaningless.

Therefore, the best practice is to use parameterized queries instead of string concatenation. There are many ORM and SQL manipulation libraries in Node.js that can be used to avoid string concatenation of SQL statements.

4. Reduce database permissions

In order to minimize database threats caused by SQL injection attacks, we can reduce the permissions of database users to the minimum. Database administrators can limit the permissions of connecting users to avoid misuse or malicious operations.

For example, you can create different database roles for different users and give them different permissions, such as reading data or writing data, etc., thereby limiting their control over the database. The simplest way to limit the operations a database user can perform is through the SQL GRANT and REVOKE statements.

This article introduces some common methods to prevent SQL injection attacks. Although in practice, the above methods do not ensure 100% security, these security best practices can minimize the risk of an application suffering from SQL injection attacks. As a Node.js developer, we should always keep in mind the importance of preventing SQL injection when performing database operations.

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