A zombie is created when a hacker uses a computer virus or trojan horse to take unauthorized control of a computer in order to use it to perform malicious tasks.
Black hat hackers will work to create a network of zombie computers – a botnet – that includes hundreds, thousands, or up to more than a million infected machines. They then use this network for malicious activity such as spam e-mail distribution and distributed denial of service attacks (DDoS). As a matter of fact, in 2005 more than 80% of all spam worldwide was sent by zombie botnets.
In effect, a zombie computer allows a hacker to perform malicious tasks using someone else’s computer, IP address, and internet bandwidth. This provides the hacker with a layer of protection against being caught, increases the computing and bandwidth resources at their disposal, and if they do get caught it's your IP address that will be flagged as fraudulent and not theirs.
Frequently Asked Questions
What are some signs that my computer is a zombie?
Some of the biggest red flags to watch for according to ZoneAlarm include a sudden decrease in performance when you aren’t using multiple programs, unexplained error messages, frequent computer crashes, messages in your email sent folder that you don’t recognize, and frequent unexpected closing of your browser.
I’m afraid my computer may be a zombie. What should I do?
You should immediately update your antivirus software and run a complete system scan. Since not all antivirus programs are created equal, it wouldn’t be a bad idea to install a second virus-removal program and rescan your computer. If you want to play it completely safe, the only surefire way to revive your computer is to completely wipe your hard drive and reinstall your operating system using the system restore method supplied with your computer.
How do I protect my computer against becoming a zombie?
As the saying goes, the best offense is a good defense. The best way to fix a zombie computer is to avoid getting infected in the first place. To do this always keep your antivirus software up to date, and don’t ever install any applications that your system flags as potentially malicious. In addition, never open an email attachment that you didn’t expect to receive, click on links in suspicious emails.
Why would someone want to create a botnet – a horde army of zombie computers?
The motivation for the malicious tasks accomplished with a botnet – spam distribution, DDoS attacks, pay-per-click fraud, and so forth – tend to fall into two categories: financial gain and to make a point. Spam e-mail is often used to advertise goods for sale, especially black-market prescription drugs. Pay-per-click fraud is often committed to earn advertising commissions for fraudulent clicks. DDoS attacks may either be an extortionary tactic to secure a website ransom, or as a means to prove one’s mettle as a black hat hacker.