Zombie or zombie computers are becoming the number one source of all malware and spam attacks. A zombie is a computer attached to the Internet that has been compromised by a hacker or a computer virus.

Zombies are commonly used for

• Sending spam
• Hack other computers
• Denial of service attacks
• Advertisement click fraud
• Phishing websites

How does the computer become a zombie?

It all begins by an attack of small virus or Trojan horse which finds the way into the compromised computer. The virus then opens a backdoor to the computer and informs the owner of the virus or hacking tool. The Trojans often delete files, disable anti-virus program to make sure that its stealth and sends the computer authentication information to the bad guy. Then the computer joins and works together as part of big a “botnet” where the task is shared by hundreds of computers around the globe.

Computers affected by Trojans can be used to launch attacks against targeted Internet sites. Several famous websites like Yahoo, ebay etc has fell prey to denial of service (DoSS) attack by zombies during 2000-04. It’s estimated that nearly 80% of all spam messages are send by zombies. Usually the owner of the computer ends up paying the band width cost of these attacks. The IP address or the ISP’s are often blacklisted by antivirus companies and it takes years to get the IP reputation back.

Zombies are used for all types of illegal activities to hide detection. When there is a cyber attack the law enforcement officers look for IP address to trace the hacker. Hackers hide behind these zombies putting the computer owner at risk.

How to find out whether my computer is a zombie or not?

• Be suspicious if you are getting huge internet bill
• Be suspicious if the computer is too slow while connected to the internet
• Type the command “netstat” and see how many open connections are there in your computer

How to prevent my computer from acting as zombie?

• As always, update your anti virus program
• Activate the firewall and set tight rules. It might be often annoying to see the firewall pop up questions to allow a program or not, but it’s good.
• Block all unwanted ports in your computer