Kinds of Attacks:

There are various different types of security attacks which can be mounted on a computer system. A few of them are surprising to people who are new to computer security issues, but they are very real and can be devastating under the right circumstances. The above Table 1 lists a few general types of attacks.

Table Some common types of attacks against computers

Further to these general attacks, Java applets could try another type of attack. Since applets are fetched to your machine and run locally, they can try to suppose your identity and do things while pretending to be you. For instance, machines behind corporate firewalls frequent trust each other more than they trust machines on the wider Internet, so once an applet has begin running on your machine behind the  firewall, it  might  try  to  access  other machines, exploiting their  trust. Another instance is mail forging: once on your machine, an applet might attempt to send threatening or offensive mail that appears to be from you. Of course, Internet mail could be forged from other machines besides your own, but doing it from your own machine creates it a little more convincing.