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Types of Threats

Nowadays there are many identified threats that could affect computer systems. New threats are also found frequently. We will provide simple descriptions for the most commonly found threats including viruses, trojans, worms, rootkits, spyware, adware, macros, DoS, etc.


Viruses are any programs that infect other application programs by adding their own code to them and get control of the infected files or the application programs. This explains how a computer virus can damage a computer system.


Trojans can carry out unauthorized actions on computers, such as deleting information on drives, stealing confidential information and so on. This kind of threat is not a virus in the traditional sense of the word (meaning it does not infect other computers). Trojans are widely spread by hackers.


Worms can exploit operating system vulnerabilities to spread itself. The type was named for the way the worms crawl from computer to computer, using networks and e-mail. This feature gives many worms a rather high speed in spreading themselves. Worms can penetrate a computer, search for network addresses of other computers, and send a burst of self-made copies to those addresses. In addition to network addresses, worms often utilize data from e-mail client address books.


Rootkits can modify computer operating systems and hide its own existence and actions such that hackers can undertake on the infected computer.


Spyware programs are designed to collect information from user's computer without their knowledge. These programs monitor and records user activities on computers and sent the information back to the developers. The collected information will be shared with or sold to any third parties.


Adware programs are designed to display advertisements on computer. These programs can also collect personal information on the computer system and send it back to their developers. They can change browser settings and create traffic that the user cannot control.


VBA programs have access to most Microsoft Windows systems such that it can execute when documents are opened. This makes it relatively easy to write computer viruses in VBA codes that are commonly known as macro viruses or simply macros.


DoS (Denial-of-Service) attack is an attempt to make computer resources unavailable to its users by massive external communications requests such that it cannot respond to legitimate traffic or responds slowly. It can make an Internet service or a communication application partly or totally down.