Web Start Security and the Cache

Question

Hi,
If the jars are signed and download occurs then webstart will verify the signature and tell the user that jars signed by user xxxxx are about to be run. Then the jars are cached by web start. My question is, what is to stop an attacker from replacing the jars in the cache with malicious ones? Does web start verify the signature on the jars when they are loaded from the cache aswell, thus preventing the jars from being changed? Or does the versioning system web start uses somehow prevent replacing the jars.
Thanks for any help,
Dave.

Answer 1

How would an attacker replace the jars with malicious ones? Through the initial signed jars? That means the initial ones are already malicious anyway, so why bother? After all, the user has already given those signed jars all-permissions anyway...
I'm sure you could devise some other means to do it using virus-like software, but all this would give you far greater control over the users machine than anything those cached jars could ever give you, even if the JNLP client did no checking on its cache whatsoever.