Types of Viruses
Computer Virus is known to be a fragment of software, responsible for infecting a computer, by getting installed by itself without taking owner’s approval or consent. Viruses has the ability to get transferred from one computer to another through programs, data files, etc.
Here this content is all about types of viruses that can be present in any computer system.
Classification of Viruses
- Macro Virus
- Boot Sector Virus
- File Virus
- Polymorphic Virus
- Source Code Virus
- Encrypted Virus
- Tunneling Virus
- Stealth Virus
- Armored Virus
- Multipartite Virus
- Browser Hijacker
- Resident Virus
Before having a descriptive idea about each virus, let us first have the idea about the basic definition of virus.
What is Computer Virus?
Virus is basically known to be a program that exhibits such characteristics that it can infect of hinder other programs existing in the computer system by modifying them. Viruses possess self-replicating nature as when it infects any program then in most of the cases, a similar copy of that particular virus is generated.
In general, it is said that viruses damage computer, server, client, or computer network however, it is not always necessary that viruses always turn out to be malicious. Though viruses can have side effects which are not always desirable within the computer system.
In simplest terminology, virus within a computer system can be understood as cold or flu virus within a human body, responsible for hindering the well being of the body.
The development of computer virus within a system causes its spreading from one host to another. Mainly, e-mails, downloaded files, software installations, and some insecured links, etc. can transfer viruses from one computer system to another.
Let us now see the various types of computer viruses in detail.
Macro Virus: Macro viruses are the result of some applications or programs that include macros like doc, pps, xls, and mdb. These basically exists in scripting languages for Microsoft programs like word, excel i.e., spread in Microsoft office thereby infecting the spread sheets.
Different from other viruses that are written in low-level language, macro viruses are written in high-level language such as visual basics. When a program that can execute a macro is run then these viruses are triggered within the system.
Boot Sector Virus: It is known to be one of the traditional viruses and is responsible for infecting the boot sector of the computer system. It basically takes the control over the system when the system starts or boots. Not only computer system, it also infects medias such as floppy disks when connected to the system. However, the file systems are not affected by these viruses and thus another name given to these viruses is memory virus.
It can get spread from one device to another, when an infected storage device is plugged in into the computer system.
File Virus: These viruses unethically get added to end part of crucial files that run the operating system thereby infecting the system. By this, the start of the program gets changed and the control jumps over the actual code and in this way, it hides itself. However, the operating system, unaware of the existence of this virus within the program gives the the same rights to this virus at the time of execution.
Hence, malicious code is inserted by this virus into the executable files. Another name for this virus is parasitic virus.
Polymorphic Virus: Through virus signature, the virus within a program can be identified. A polymorphic virus is the one that avoid its detection by virus signature by changing itself every time during installation. Though the virus do not changes its behaviour but its signature is changed.
Hijacker Virus or Browser Hijacker: This virus is responsible for targeting and modifying browser’s setting of any computer system. Sometimes it is given the name browser redirect virus and the reason behind this is that when this virus is activated within any system, then unknowingly, the browser is directed towards some malicious websites where the user actually does not want to visit.
It changes the browsers setting of a computer system thereby harming the system.
Encrypted Virus: Here the name itself is indicating that this virus appears to exist in encrypted manner and therefore it becomes very difficult to detect it. There is a decryption algorithm that is present within the virus and thus, at the time of execution first the virus undergoes decryption and then its execution is performed.
E-mail Virus: This type of virus is transported by the means of e-mail messages. In order to multiply itself, this virus automatically copy itself and generates mailing copies that get transmitted to hundreds of people that are present in the address book of actual victim.
Logic Bomb: this type of virus brings a logical code intact with it and it remains attached till the time certain conditions are satisfied. When the specific condition resolves then a certain function gets triggered. The condition can be anything such as suppose there is a virus that gets executed when it infects some other hosts. Logic bomb has a subset called time bomb, that has the ability to get triggered at a particular date and time.