Siri’s Speech Recognition Lacks Security

Siri is a speech-recognition application found in all iPhone 4S smartphones. This is a software and not an application, because you cannot download it just like other Apps on your phone. You cannot see an icon of this on your screen, but rather a button that you press to activate it. With this kind of setup, it seems that iPhone 4S found its first security issue with Siri.
You can send messages and emails even with your phone locked. No passcode needed to activate it. Is there any way this problem could be avoided?

