Java socket bridge

So I'm trying to create a socket bridge in Java to allow me to use actual sockets in Javascript. It works like this:
I include the applet where I want to use sockets, get a reference to it with Javascript, and then I can call applet code by using ref.code.

The applet must be signed and given permission so it can make connections to any domain. Only the main thread has these permissions. You also can't call the socket functions directly from Javascript.

My question is if I start a thread from the main thread will it have the same permissions as the main thread? Is it possible to call code from a thread and have that code run in the thread?

>>11

I've heard that having built in features like this for java script is a security vulnerability, but I don't really understand why myself. I guess it could try to open a bunch of sockets on a bunch of ports to find out what port are in use? And reporting results back to a server? Maybe it could try to connect to other machines on your local network, and report results? Or I guess if you are on a LAN, and yall depend on a firewall on the main router for security, then malicious website could have malicious javascript execute on your computer, from within the firewall, and then have less restricted access to the other machines on the LAN? And possibly try to perform some exploits on software listening on ports that would have been blocked by the firewall? Maybe it could open a socket to the host computer and mess up a program listening on a port on your own machine? I dunno.