CATEGORIES OF COMPUTER VIRUSES


There are following basic categories of viruses3.1 Macro Viruses

These viruses infects all the files that contain macros

i.e.doc,pps,xls and Medb, they affect the macros ,templates and

also the documents that are present in the files

Examples are:

• Relax

• bablahs

• Melissa. A

• 097M/Y2K


3.1 Macro Viruses

 These viruses infects all the files that contain macros i.e.doc,pps,xls and mdb,

 they affect the macros ,templates and also the documents that are present in the

 files Examples are:

 Relax

• bablas

• Melissa. A

• 097M/Y2K


 3.2 Memory Resident Viruses

They attack inside the computer memory, it gets activated

when the operating is running and infects all other files, they

are hidden in RAM.

Example are:

• CMJ

• meve

• randex

• mrklunky


3.3 Overwrite Viruses 

These viruses delete the efficient information available in a file,at the end it leaves the file fully or half useless,it replaces the content but do not change the size of the file Examples are: 

• Trj.Reboot 

• way 

• trivial.88.D


3.4 Direct Action Viruses

 These types of virus duplicates and takes action when they are executed, they infect the files in the directory or the folder in it . AUTOEXEC.BAT, they are found in the root directory.

 Example : Vienna virus 

 3.5 Directory Virus 

Other name for this type of virus is cluster virus,they infect the directory of computer it does this by changing the path of file location,located in the disk but after affecting it affects the entire directory. Example is: dir-2 virus 

3.6 Web Scripting Virus

 Mostly the web pages include complex codes with the purpose to create an interactive and interesting content, these codes are used to create unwanted actions, they comes from infected WebPages. Example is: 

JS.Fortnight – a virus that spreads via malicious emails. 


3.7 FAT Viruses

 They attack the file allocation table (FAT) which is the part to store every information. Examples is: the link virus Polymorphic Virus They do their own encrypting and programming in different style when they infect the computer, they use different encryption and algorithms, it makes it difficult for the antivirus to trace it. 

Examples are: 

 Marburg 

• tuareg 

• Satan bug 

• elkern