A virus is a small piece of malicious software code that can replicate itself and spread from one host to another by attaching itself. Initially, the virus is inactive until the file is opened and used. Viruses are designed to hinder system performance. Because the impact of these viruses can cause loss of confidential data and system failures.
Ex: Blaster, Slammer, Nimda, Code-Red, Creeper.
Types of Viruses:
There are various types of computer viruses that play an important role in the system. A computer gets infected by malicious copywriting and it comes in different forms in a computer system in different ways. Listed below are some computer viruses,
● Boot Sector Virus: This type of virus can take over when the computer starts or restarts. One way to spread is by connecting an infected USB drive to a computer.
● Browser hijacker: This type of virus "captures" certain functions of a browser and you can be automatically redirected to an unwanted website.
● Direct Action Virus: This type of virus starts working when you run a file containing the virus. Otherwise, it remains in sleep mode.
● File Infector Virus: This common virus adds malicious code to executable files. Files that are used to perform certain actions or functions in the system.
● Resident Virus: This is a general term for any virus that resides in the memory of a computer system. A resident virus can be launched at any time during the loading of the operating system.
● Multiparty virus: This type of virus infects and spreads in many ways. It can infect both program files and system sectors.
● Macro virus: Macro viruses are written in the same macro language used in software. Such viruses spread when an infected document is opened, often via email attachments.
● Polymorphic virus: A polymorphic virus changes its code every time an infected file is executed. It does this to avoid antivirus programs.
● Virus replacement: This type of virus is capable of erasing data when it replaces itself. They replicate themselves like any other computer virus, but they also delete data in the process.
● Space filler virus: This type of virus is a rare computer virus that tries to install itself by filling empty parts of a file. Using this virus, it can infect a file without changing the file size, making it difficult to detect.
● Web script virus: This type of virus uses code from web browsers and web pages. If you use such a website, a virus may infect your computer.
How many phases in viruses?
The life cycle of a virus takes place in four stages like Dormant Phase, Propagation Phase, Triggering Phase, Execution Phase.
| Phases | Descriptions |
|---|---|
| Inactive Phase | This is the first phase of a virus, where viruses are in an ideal state and need some activation, thus requiring a date, time or other program action or event. |
| Propagation stage | This is the second stage where the virus creates its own copies. |
| Launch Phase | This is the third phase where viruses are activated and perform their required functions and deliver payloads. |
| Execution Stage | This is the final stage of the virus where the payloads are executed and perform real functions that can be harmless or destructive. Here, the payload is a small piece of malicious code that executes malicious content. |
What are the characteristics of a computer virus?
● Changes to your home page.
● Repetitive popups.
● System slowness.
● Undefined crashes.
● Unknown programs that run in the background when the computer starts.
● Unsolicited emails are being sent from your email account.
How to protect your computer from viruses?
● It is highly recommended to set a strong password (eg Tamil names).
● Use a reliable antivirus product and keep it updated with the latest virus definitions.
● Back up your PC or computer regularly.
● Always check email attachments before opening them.
● Install Ad-block to avoid unwanted ads.
● Run a virus scan frequently.
● Avoid opening suspicious links.
● Avoid clicking on pop-ups.
● View downloads.
Also Read : Types of Malware Threats and How to recognize them
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