Security in Node.js Applications: Denying SQL injection attacks

SQL injection is another large class of security exploits, where the attacker puts SQL commands into input data. See for an example.

The best practice for avoiding this problem is to use parameterized database queries, allowing the database driver to prevent SQL injections simply by correctly encoding all SQL parameters. For example, we do this in the SQLite3 model:

db.get(“SELECT * FROM notes WHERE notekey = ?”,     [ key ] …);

This uses a parameterized string, and the value for key is encoded and inserted in the place of the question mark. Most database drivers have a similar feature, and they already know how to encode values into query strings. Even if a miscreant got some SQL into the value of key, because the driver correctly encodes the contents of key the worst that will result is an SQL error message. That automatically renders inert any attempted SQL injection attack.

Contrast this with an alternative we could have written:

db.get(‘SELECT * FROM notes WHERE notekey = ${key}’, …);

The template strings feature of ES6 is very tempting to use everywhere. But it is not appropriate in all circumstances. In this case, the database query parameter would not be screened nor encoded, and if a miscreant can get a custom string to that query it could cause havoc in the database.

In this section, we learned about SQL injection attacks. We learned that the best defense against this sort of attack is the coding practice all coders should follow anyway, namely to use parameterized query methods offered by the database driver.

In the next section, we will learn about an effort in the Node.js community to screen packages for vulnerabilities.

Source: Herron David (2020), Node.js Web Development: Server-side web development made easy with Node 14 using practical examples, Packt Publishing.

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