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Lære Input Validation and Sanitization | Best Practices for Secure Software Development
Fundamentals of Information Security for Developers

bookInput Validation and Sanitization

Input validation and sanitization are essential techniques in secure software development.

Note
Definition

Input validation is the process of checking data provided by users or other systems to make sure it is correct, expected, and safe to use. Sanitization involves cleaning or modifying this data to remove anything potentially harmful before using it within your application.

These practices are vital because user input is a common source of security threats. Attackers often exploit weak input handling to steal data, gain unauthorized access, or disrupt services. Without proper checks and cleaning, input can lead to serious issues like SQL injection, cross-site scripting, or system crashes.

Developers use input validation and sanitization daily — for example, when processing form data, file uploads, or API requests. Validation ensures data matches what's expected (like a correctly formatted email), while sanitization removes or neutralizes harmful characters or content.

Ignoring these steps makes applications vulnerable to malicious input and potential data breaches. Proper validation and sanitization greatly reduce these risks and help keep systems secure and reliable.

Key Takeaways: Input Validation and Sanitization

  • Input validation is your first line of defense against malicious data;
  • Always check input against expected formats, types, and length before processing;
  • Use allow-lists (whitelists) rather than block-lists (blacklists) to define valid input;
  • Input sanitization removes or encodes potentially harmful characters from user data;
  • Never trust data from external sources, including users and third-party systems;
  • Combine validation and sanitization for maximum protection against attacks such as SQL injection and cross-site scripting.

By consistently applying these best practices, you reduce vulnerabilities and help ensure your software remains secure against common threats.

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Why is input validation important in secure software development

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bookInput Validation and Sanitization

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Input validation and sanitization are essential techniques in secure software development.

Note
Definition

Input validation is the process of checking data provided by users or other systems to make sure it is correct, expected, and safe to use. Sanitization involves cleaning or modifying this data to remove anything potentially harmful before using it within your application.

These practices are vital because user input is a common source of security threats. Attackers often exploit weak input handling to steal data, gain unauthorized access, or disrupt services. Without proper checks and cleaning, input can lead to serious issues like SQL injection, cross-site scripting, or system crashes.

Developers use input validation and sanitization daily — for example, when processing form data, file uploads, or API requests. Validation ensures data matches what's expected (like a correctly formatted email), while sanitization removes or neutralizes harmful characters or content.

Ignoring these steps makes applications vulnerable to malicious input and potential data breaches. Proper validation and sanitization greatly reduce these risks and help keep systems secure and reliable.

Key Takeaways: Input Validation and Sanitization

  • Input validation is your first line of defense against malicious data;
  • Always check input against expected formats, types, and length before processing;
  • Use allow-lists (whitelists) rather than block-lists (blacklists) to define valid input;
  • Input sanitization removes or encodes potentially harmful characters from user data;
  • Never trust data from external sources, including users and third-party systems;
  • Combine validation and sanitization for maximum protection against attacks such as SQL injection and cross-site scripting.

By consistently applying these best practices, you reduce vulnerabilities and help ensure your software remains secure against common threats.

question mark

Why is input validation important in secure software development

Select the correct answer

Alt var klart?

Hvordan kan vi forbedre det?

Takk for tilbakemeldingene dine!

Seksjon 3. Kapittel 1
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