During a recent log review, an analyst discovers evidence of successful injection attacks. Which of the following will best address this issue?

Input validation is the best solution because it directly addresses the root cause of injection attacks. By validating all user-supplied input against expected formats, types, and lengths, the application can prevent malicious code or commands from being processed. This ensures that only legitimate data is accepted, neutralizing the injection attempt before it can succeed. Authentication verifies user identity but doesn't prevent an authenticated user from submitting malicious input. Secure cookies protect session integrity but don't stop injection attacks themselves. Static code analysis can identify potential vulnerabilities in code before deployment, but it doesn't actively prevent attacks on a running system; input validation is a runtime control.