Patched code sample

import subprocess

def apply_ntp_configuration(config):
    """
    Securely applies the NTP configuration.

    This function mitigates command injection by passing the 'ntp_server'
    value as an element in a list to subprocess.run(), rather than
    embedding it in a shell command string.
    """
    ntp_server = config.get('ntp_server')
    if ntp_server:
        # The command is built as a list of arguments.
        # This ensures that the ntp_server value is treated as a single,
        # literal argument and is not interpreted by a shell.
        command = ['ntpdate', ntp_server]

        # Execute the command. shell=False is the default and secure setting.
        # An attacker providing 'some.server; rm -rf /' would cause the
        # ntpdate command to fail, but the 'rm -rf /' part would not be
        # executed.
        try:
            subprocess.run(command, check=True, capture_output=True)
        except (subprocess.CalledProcessError, FileNotFoundError) as e:
            # In a real application, this error would be logged.
            print(f"Failed to update time using '{ntp_server}': {e}")