MS's 1st Immutable “Law�

• If a bad guy can persuade you to run his program on your computer, it's not your computer anymore.

• It's an unfortunate fact of computer science: when a computer program runs, it will do what it's programmed to do, even if it's programmed to be harmful. [...] Once a program is running, it can do anything, up to the limits of what you yourself can do on the machine. [...] It could open every document on the machine, and change the word "will" to "won't" in all of them. [...] It could install a virus. It could create a "back door" that lets someone remotely control your machine. [...]

• That's why it's important to never run, or even download, a program from an untrusted source [...]