Types of Computer Viruses

A virus is program or code that when executed on your computer will cause lots of issues for your computer operating system and its associated file system,furthermore the performance of that computer will significantly decrease.Most viruses are spread by means of replication, this is where it will copy itself to other programs, documents and files on that computer.

Viruses can be placed into four categories namely:

-File Infector
-Boot Sector Infector
-Macro Virus

File Infector
File infector viruses will tend to seek out other files on the computer and then infect them by attaching itself to executable extentions files such as (.exe),(.com), most times these files are used to run programs.File infectors would inject itself into memory and from there it would load into other places.

Boot Sector Infector
A boot sector virus infects the boot sector of a computer hard drive.As the computer reads and execute programs in the boot sector, the virus loads in memory and from there it usually gains control over other computer functions and to different areas of the computer.

Multipartite Infector
A multipartite virus is clearly what the name says,once loaded the virus can infect various areas of a machine at one given time.A good example would be a boot sector virus and a file infector virus bundled in one.These types of virus are very dangerous because they can spread faster and can cripple your system within a short period of time.

Macro Virus
Some programs today have macros capabilities embedded into them which are disabled by default.The problem exists when this capability is enabled and you get infected by a macro virus.This macro virus will automatically load onto the program ultimately corrupting similiar files thus  affecting performances.An example of these programs might be microsoft excel or spreadsheet documents, users should be aware of these and should note that they will affect programs that needs macros to run.You should not open any documents in attachments in emails or from any source without scanning it with an antivirus software.

Polymorphic Virus
The polymorphic type of virus mutates or changes form as it infects other files within your computer system.These types of viruses are usually encrypting in nature which allows them to be hidden easily.Most anti-virus software will find it difficult to remove, it takes usually a combination of anti-virus and  anti-malware software to remedy these.

Metamorphic Virus
Metamorphic Viruses are malicious little programs that have the ability to rewrite and re-encrypt their code upon infecting every new computer, this allows them to hide from anti-virus and anti-malware softwares.As the virus spreads to another machine, it is as though it is a completely new code because of it`s self modifying characteristics.

A worm  usually replicate itself onto whatever media it gets into contact with whether it is on a flash drive, hard drive, emails, etc.These types of virus are completely independent and it will continue to move around replicating itself and whilst it is replicating itself within your computer it could possibly be making your computer vulnerable to outside attack.

 Trojan Horse
A  trojan horse comes under the disguise as though it is a legitimate program e.g a game, software or application, etc ,when in fact it has malicious code hidden deep in its structure.These programs when downloaded and installed on a user`s system they tend to steal data or open communication ports on your computer which will further allow your computer to become vulnerable  while online.

Spyware are programs that gather information about a user`s browsing habits mostly for marketing purposes or to further deliver targeted advertisements.They are usually packaged with legitimate programs and are mostly offered  as free downloads online.

Adware are little programs that are designed to monitor  user`s browsing habits and may further display Ads in the form of pop ups to that user.Some Adware tend to change a user`s browser homepage and replace it with it`s own.Though these programs are not as serious as the others they can be very annoying. 

These are programs written for the purpose of exploiting vulnerabilities within a given computer operating system.Whenever a rootkit gets downloaded onto a computer from the internet it will look for all known vulnerabilities for that specific operating system.Most rootkits are programmed to leave backdoors in your computer so that it can be remotely accessed by third parties. 

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