Destructive Trojans

• Destructive Trojans work similarly to viruses. Once they have been installed, they attack programs by deleting files, folders, registry entries and system components. As a result, the infected programs have slow launch times, freeze during use or eventually crash. Destructive Trojans also alter startup and shutdown functions in the registry and system folders and cause computer performance to drastically deteriorate. The inevitable result is the constant displaying of the "blue screen of death" or a system crash.
  
  

Remote-Access Trojans

• Remote-access Trojans give a hacker control of your computer. Once they have been installed and executed, an attacker can use his computer to monitor browsing activity, alter startup functions and reconfigure registry and system settings. If they are not completely removed from your computer, the result would be a damaged system. Remote-access Trojans are usually hidden in online game downloads and small program downloads. Many websites (e.g,. warez and torrent sites) secretly bundle them together with downloads and infect your computer when you install a downloaded game or program.
  
  

Data-Sending Trojans

• Data-sending Trojans are another elite group of dangerous Trojans that secretly install on your computer, mainly through infected emails and downloaded files from the Internet. Once they have been installed, they provide an attacker with sensitive information such as passwords, credit card numbers and log files. They also install keyloggers, which record keystrokes every time you type personal information. The collected information is then sent to the attacker's server, where it's used to attempt to figure out passwords and credit card numbers.
  
  

Solution

• Run a virus scan frequently to disrupt Trojan processes and delete malicious files linked to them. If you do not have an antivirus program, consider AVG, which is both free and powerful in detecting malicious programs. It is important to clear your browser history and cache frequently to prevent an attacker's access to email addresses, passwords and credit card information. Run anti-malware programs such as Malwarebytes' Anti-Malware to detect and remove Trojans such as rogue anti-spyware programs (e.g., Antivirus 2009) from system folders and the registry.
  
  

Warning

• Do not download programs, games or files from malicious websites (e.g. warez or torrent sites) because there's no telling what is bundled with the downloads. You could unknowingly install a Trojan, which can severely damage system components. Do not open infected emails, which come with attachments and no message. Make sure you update your antivirus program frequently so that it has the latest virus and spyware definitions to combat the latest threats. Do not use the Internet if you do not have an antivirus program installed on your computer, because you're basically rolling out the red carpet for Trojans and other malicious programs.