How do you keep user input safe from malicious code?

User input is essential for any web application that interacts with users, such as forms, surveys, quizzes, comments, or chat. However, user input can also be a source of security risks, as malicious users can try to inject harmful code or commands into your web application, compromising its functionality, data, or users. This is known as code injection, and it can have serious consequences for your web development project. In this article, you will learn how to keep user input safe from malicious code, by following some best practices and using some common tools and techniques.

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1 Validate input

The first step to prevent code injection is to validate user input before processing it. Validation means checking if the input meets certain criteria, such as format, length, type, or range. For example, if you expect a user to enter a phone number, you can validate that the input only contains digits and has a valid length. Validation can be done on both the client-side and the server-side, using JavaScript, HTML, or PHP, depending on your web development stack. Validation can help you filter out invalid or suspicious input, and reject or sanitize it before it reaches your web application logic.

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J Ferin Joseph

10x Salesforce Certified (SFCC,SFMC,SFDC,DXP,AI) | PHP, C#, NodeJS, HTML, JS, CSS | AWS, Heroku | “Learn to Earn Knowledge”
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Field validation is must irrespective of the technology in which the application gets build. Both front-end and back-end has its own methods to validate fields. Front-end will be validated based on the value pattern (text, number, symbols, etc..), content type (image, document, text, etc..). Back-end will be validated based on the form method (POST, GET, etc..), form encryption (plain text, multipart form-data, etc..). Back-end validation should also have validations like CSRF/XSRF, ORIGIN (self, cross) for security purposes additional to regular validation.

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2 Sanitize input

The second step to prevent code injection is to sanitize user input before storing or displaying it. Sanitization means removing or escaping any potentially harmful characters or symbols from the input, such as quotes, brackets, slashes, or semicolons. These characters can be used to break out of the intended context of the input, and execute malicious code or commands. For example, if you display user input in a web page, you can sanitize it by using HTML entities or encoding functions, to prevent cross-site scripting (XSS) attacks. Sanitization can be done on both the server-side and the client-side, using PHP, JavaScript, or HTML, depending on your web development stack. Sanitization can help you prevent malicious input from affecting your web application or your users.

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J Ferin Joseph

10x Salesforce Certified (SFCC,SFMC,SFDC,DXP,AI) | PHP, C#, NodeJS, HTML, JS, CSS | AWS, Heroku | “Learn to Earn Knowledge”
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Input field values sanitation with html encoding and decoding will avoid special characters which can affect there processing at database query level.

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3 Use parameterized queries

The third step to prevent code injection is to use parameterized queries when interacting with databases. Parameterized queries are a way of separating the user input from the SQL query, by using placeholders or parameters instead of directly inserting the input into the query. For example, instead of writing a query like this: sql = "SELECT * FROM users WHERE username = '" + input + "'" You can write a query like this:

sql = "SELECT * FROM users WHERE username = ?"
params = [input]

Parameterized queries can be done on the server-side, using PHP, Python, or Java, depending on your web development stack. Parameterized queries can help you prevent SQL injection attacks, which can compromise your database data or structure.

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4 Use HTTPS and SSL

The fourth step to prevent code injection is to use HTTPS and SSL when transmitting user input over the internet. HTTPS and SSL are protocols that encrypt the communication between your web server and your web browser, making it harder for attackers to intercept, modify, or spoof the user input. For example, if you use HTTPS and SSL, an attacker cannot see or alter the user input in transit, or pretend to be your web server or your web browser. HTTPS and SSL can be enabled on your web server, using certificates and keys, depending on your web development stack. HTTPS and SSL can help you protect the confidentiality and integrity of your user input and your web application.

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Marco Nuñez

Engineering Manager
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In production environments, https with ssl should always be used to ensure secure communication between systems and the client. Certificates can be obtained for free or for a fee, ensuring that the certifying entity is trustworthy. This can easily be seen in the URL when it's not secure, or the browser will indicate it.

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5 Test and update your web application

The fifth step to prevent code injection is to test and update your web application regularly. Testing means checking your web application for any vulnerabilities or errors that could allow code injection, using tools such as scanners, analyzers, or pentesters. For example, you can use tools like OWASP ZAP, Nmap, or Burp Suite, to scan your web application for common code injection flaws, and fix them accordingly. Updating means keeping your web development stack, such as your web server, your database, your programming language, or your frameworks, up to date with the latest security patches and fixes. For example, you can use tools like Composer, NPM, or Pip, to update your web development dependencies, and avoid any known security issues. Testing and updating can help you detect and prevent code injection, and improve your web development security and performance.

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6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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How do you keep user input safe from malicious code?

1

2

3

4

5

6

1 Validate input

2 Sanitize input

3 Use parameterized queries

4 Use HTTPS and SSL

5 Test and update your web application

6 Here’s what else to consider

Web Development

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How do you keep user input safe from malicious code?

1

2

3

4

5

6

1 Validate input

2 Sanitize input

3 Use parameterized queries

4 Use HTTPS and SSL

5 Test and update your web application

6 Here’s what else to consider

Web Development

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