Validating inputs is the process of ensuring that user-provided data meets expected formats, types, and constraints before being processed by a system. It can include checking for correct data types (e.g., numbers instead of text), enforcing length restrictions, and using whitelists for accepted values.
Input sanitization is the process of cleaning user input to prevent security threats like SQL injection, cross-site scripting (XSS), and command injection. It ensures that data entered into a system is safe by removing or encoding potentially harmful characters.
Validating inputs and proper input sanitization help protect applications from malicious attacks and prevents unintended system behavior. This helps prevent errors, security vulnerabilities, and malicious attacks like SQL injection or cross-site scripting (XSS). Through both processes, applications maintain data integrity and security while reducing the risk of unexpected behavior.
Here is the step-by-step guide to validating inputs and input sanitization.
• Identify all points where your application accepts user input (e.g., form fields, APIs, query strings, file uploads).
• Recognize that any external input, including data from APIs, is potentially untrustworthy.
• Specify the type, format, and range of acceptable data for each input. For example:
• Email: Must match a regex for valid email addresses.
• Age: Must be a number between 18 and 100.
• Text Fields: Limit length and disallow certain special characters.
• Client-Side Validation: Implement basic validation in the front-end for a better user experience. For instance, ensuring that required fields are not left blank.
• Server-Side Validation: Always enforce strict validation on the server side, as client-side checks can be bypassed by attackers.
• Use libraries or frameworks that provide built-in validation functions (e.g., Express.js for Node.js, Django Validators in Python).
• Remove or escape unwanted characters from input to ensure they cannot harm your system. Examples include:
• Stripping HTML tags to prevent cross-site scripting (XSS).
• Escaping special characters like \, ', and " to prevent SQL injection.
• Normalizing data formats, such as trimming white spaces from strings or standardizing date formats.
• Use established libraries or built-in functions to sanitize inputs (e.g., OWASP’s ESAPI for Java, Python’s bleach library).
• Encode user-provided data before rendering it in the browser or other downstream systems. For example:
• Use HTML entity encoding to neutralize special characters like < and >.
• Use parameterized queries or prepared statements for database operations to prevent SQL injection.
• Reject any input that does not meet your predefined criteria. Be explicit in what you allow rather than what you block.
• Use whitelisting (accept known good values) instead of blacklisting (block known bad values), as attackers can find new ways to bypass blacklists.
• Perform security testing to ensure validation and sanitization mechanisms are working. Use automated tools and manual techniques to test for vulnerabilities like SQL injection, XSS, and file upload exploits.
• Log rejected inputs for analysis and to detect potential attack attempts.
• Use monitoring tools to identify unusual patterns in input data that might indicate new attack vectors.
By sanitizing and validating inputs effectively, you safeguard your application against many common vulnerabilities, ensuring better security and a smoother user experience.
Pro Tip: Regularly update your validation logic to address emerging threats and incorporate lessons from security audits. See how Symbiotic's AI Security Tool can help you with all of your secure coding needs by checking out our solutions here.
