My wife’s uncle’s son (cousin?) sent me these questions and asked me to help him with a school project. If he, and his parents, had known how I was going to answer they might not have wanted my thoughts.

What’s the best way to protect your computer from hackers?
About how long does it take for hackers to write a virus for a new computers?
What are viruses?
How do viruses get into your computer?
If a hacker hacks into your computer, can they use it to hack another persons computer?
Are there any other ways to protect your computer from viruses other than fire walls?
What’s the best thing to do if your computer gets a virus?
What’s the worst thing to do if your computer gets a virus?
Are some computers safer from hackers than other computers? If so, what are they?
Can a fire wall be penetrated by hackers?

Let’s start by examining the phraseology. I’m sure the questions were written and assigned by your teacher, but before going into the specifics we need to look at the meaning of the word “hacker”.

* What is a hacker?

If you ask the mass media, law enforcement or security software vendors—that is, people with a vested interest in the answer—you’ll get the standard answer of bad people who want to break into your computer and steal your identity. In fact, that standard answer couldn’t be more wrong. A hacker is just someone who explores technology; someone who pushes the limits of gadgets, software, computers, networks, to make them do things they weren’t necessarily designed to do.

The typical definition of “hacker” actually defines a criminal, plain and simple. A person who would break into your computer, steal your identity, crash your network, unleash viruses, or any of the other doomsday scenarios breathlessly predicted on the nightly news is not a hacker; he is a criminal. A hacker might penetrate an e-commerce Web site’s order processing system to expose a weakness that could lead to identity theft, and do whatever is necessary to ensure that the vulnerability is patched. A criminal would simply steal the credit card numbers. Hackers figured out how to install their own software on the Apple iPhone; a criminal would be more likely to just steal the phone and re-sell it.

Do you see the difference?

With that said, I’ll answer your questions, substituting “criminal” for “hacker” where appropriate.

* What’s the best way to protect your computer from criminals?

Always be aware that there are bad people who want to steal your information or maliciously crash your computer. Awareness of the threat is the first step to protecting yourself.
Practice safe computing. Use strong passwords on your accounts, and different passwords for each account. Keep your operating system updated with the latest security patches, and keep the software you use updated as well. Don’t send personal data, including user names and passwords, in clear when connected to unknown or possibly insecure networks.

* About how long does it take for criminals to write a virus for a new computers?

New vulnerabilities are typically exploited almost immediately after being made public. For example, Microsoft releases a set of security updates on the first Tuesday of every month—so-called “Patch Tuesday.” The day after this has been dubbed “Exploit Wednesday,” because talented malicious programmers are able to reverse-engineer the Microsoft security updates to determine exactly what was fixed, and then release a virus (or other malicious software) to exploit this vulnerability.

* What are viruses?

In general terms, a computer virus is a program that mimics the function of a biological virus; it infects a host (a computer), spreads to other hosts (by email, on malicious Web sites or by other means) and causes damage (deleting files, stealing personal data, etc.).

* How do viruses get into your computer?

Many specific methods are used, but in general computers are infected through exploitation of unpatched vulnerabilities. For example, if Microsoft Internet Explorer has a known vulnerability where opening a certain type of file could crash the browser, a virus could infect such a file and wait for the user to open it. When the file is opened and the browser crashes, the virus is activated and free to do its damage.

Most viruses are transmitted by networks (e.g. Local area networks, Internet, email, file-sharing) but there have been many instances of infected distribution media such as CD-ROMs.

* If a criminal hacks into your computer, can they use it to hack another persons computer?

Yes. This is usually referred to as a “botnet,” or a network of bots—”bot” is a slang term for a usually non-destructive virus that provides an intruder full control of the host computer. Botnets spread using the same methods as regular viruses, but once a certain number of computers are infected they can begin communicating with each other (unknown to the owner of the computer, of course) and using their combined power to overload networks, infect other computers or other malicious activity.

* Are there any other ways to protect your computer from viruses other than fire walls?

Technically a firewall doesn’t protect your computer from viruses; it protects your computer or network from unauthorized intrusion from outside. That intrusion may be for the purpose of spreading a virus, or it may be to break in to a database of credit card numbers or any other reason. That said, there are two basic kinds of firewalls: software and hardware. A software firewall is a program that runs on your computer and monitors the network interface for unauthorized traffic. A hardware firewall is an entirely separate piece of equipment that filters network traffic before it reaches your computer. Either or both may be useful depending on your needs and situation.

Anti-virus software can also be useful to protect your computer against viruses. It’s important to realize that the large anti-virus software vendors have a vested interest in the continuing existence of malicious software, not to mention typically rating quite low in independent surveys. Many free or low-cost anti-virus solutions are available, and most of these are actually better than the major names.

* What’s the best thing to do if your computer gets a virus?

Disconnect it from the network to prevent further spread. Turn it off. Most anti-virus software provides offline recovery tools—that is, a way to remove the virus from your computer while not letting the virus spread or do any more damage. It’s better, though, to practice safe computing and prevent yourself from getting infected in the first place.

* What’s the worst thing to do if your computer gets a virus?

Ignore it.

* Are some computers safer from criminals than other computers? If so, what are they?

I think the question is aimed at describing brands or models of computers, but unfortunately it’s not that simple. Any computer, poorly secured, is vulnerable; conversely, any computer can be properly secured and protected. My computer is relatively safe from penetration and exploitation by criminals because I keep the operating system and software updated, I use firewall and anti-virus software and practice safe computing.

* Can a fire wall be penetrated by criminals?

The only security that can’t be penetrated is turning off and unplugging the machine. Anything else is potentially vulnerable. Security is an ongoing process, and security vendors and criminals are engaged in an ongoing endless cat-and-mouse game where malicious programmers will find a new vulnerability, and security vendors will patch it before it can be exploited. The best way to protect yourself is to stay informed.