To download a patch for Microsoft Internet Explorer 3.* and 4.*, follow this link:
For Netscape Navigator/Communicator Versions 2.* , 3.*, and 4.*, go to the following:
In Java the user may or may not be informed that an applet (an executable Java program embedded in a Webpage) is being downloaded into their browser. The real shock comes when a user inadvertantly downloads a hostile applet (an applet which provides an attack against a user's system). There are many different things hostile applets can do to wreak havoc on your system. Among a few of the most noteworthy are the following:
Hostile applets have also been known to have the capability to contact machines behind firewalls, send off a listing of a user's directories, track a user's actions through the web, generate machine code, make directories readable and writeable, and send off email without intention.
This document obtained from infosec. no author mentioned.