What is Malware?
Malicious software (malware) is the wide range of software applications developed with a malicious intent. The methods used for malware installation is unlike any other software installation you are accustomed to because malware is installed through devious means. People often use the terms virus and malware interchangeably. However, a virus is a type of malware. Other major malware types include:
A virus contains malicious code that attaches itself to an application. When the infected application is executed, the virus is launched and will attempt to spread to other computers. A virus typically will not cause immediate damage as it needs time to replicate in order to infect other computers. Eventually, the virus will deliver its payload. The payload can cause significant damage such as deletion of critical system files, random reboots of your computer, and can corrupt hard drives and make them unbootable. Viruses are delivered to systems in a variety of ways. Email is the most common method for spreading viruses. For example, spammers will email viruses as attachments and will entice users to download and open the attachment, which in turn will execute the virus. Users can also transmit viruses by using infected USB flash drives. Most operating systems have Autorun enabled, which enable infected USB flash drives to execute the virus as soon as the device is plugged into the machine.
Trojan horses trick users by posing as legitimate applications. For example, a Trojan horse may appear to be a game or a screensaver. A deceived user will download the application and the Trojan horse is released once the user executes the program.
Unlike viruses and Trojan horses, worms do not need to be executed. Worms reside within memory and can travel throughout a network without depending on an infected computer application or interaction. Worms replicate themselves exponentially and can literally crash networks by consuming its bandwidth.
Spyware is installed on a machine without the user’s awareness or consent. Spyware attempts to gather specific user information and send it to a third party. You can determine if your computer is infected with spyware if your Internet home page has suddenly changed, if your web browser redirects web searches, or if additional software has been installed on your machine. Another form of spyware is adware. Adware launches pop-up windows to display unwanted advertisements.
A rootkit is the combination of programs designed to infect your computer without being detected. Your antivirus application communicates with your operating system to identify threats. However, rootkits breaks down this communication process. Consequently, your antivirus software will think that everything is fine and will not report that your computer is infected.