A virus is a malicious program that self-replicates by duplicating itself into another program. In other words, the computer virus spreads by itself into other executable code or documents. The purpose of creating a computer virus is to infect vulnerable systems, gain admin control, and steal user sensitive data. Hackers design computer viruses with malicious intent and prey on online users by tricking them.
Virus are always dormant not until they are caused to execute by circumstances or actions on the computer. In order for a virus to infect your computer, you have to run the infected program, which in turn causes the virus code to be executed.
However, once the virus infects your computer, the virus can infect other computers on the same network. Stealing passwords or data, logging keystrokes, corrupting files, spamming your email contacts, and even taking over your machine are just some of the devastating and irritating things a virus can do. While some viruses can be playful in intent and effect, others can have profound and damaging effects. This includes erasing data or causing permanent damage to your hard disk. Worse yet, some viruses are designed with financial gains in mind.
Types of Computer Viruses
#1. File Viruses: These types of viruses are the most common, and mostly infect open files and program libraries on an operating system. They infect the computer system by targeting executable files (.exe), file infector viruses slow down programs, and damage system files when a user runs them.
#2. Boot Viruses: One of the easier viruses to avoid, this virus hides out in a file on a USB drive or email attachment. When activated, it can infect the system’s master boot record to damage the system. Boot viruses are executed every time a computer is booted so the virus will also be loaded into memory on every startup and spreads to every disk that the system reads. They are typically very difficult to remove, so bootable antivirus disks are needed to fix boot sector viruses.
#3. Network viruses: These viruses travel through network connections and replicate themselves through shared resources including drives and folders. Basically, this type of virus spreads out through Local Network Area (LAN) and through the internet.
#4. Macro viruses: These viruses are embedded in Microsoft Office or PDF files. Many people who are careful about never opening strange applications forget that these sorts of documents can themselves contain executable code. These macro viruses may inflict damage to the document or to other computer software but are relatively harmless, and are often spread as an e-mail virus. Macros are used in most word processing programs such as Microsoft Office in order to automate or simplify recurring tasks in documents.
#5. Web scripting viruses: