Input sanitization and the use of prepared statements or parameterized queries are the most effective process-level remediation strategies for preventing command injection vulnerabilities. This is because they both work to ensure that any command or query executed by the application treats user input as data rather than executable code, thus preventing attackers from interfering with the commands or queries the application runs. Although updating application frameworks and verifying the use of a WAF can provide additional security benefits, they are not direct mitigation strategies for command injection at the process level.