Types of Computer Viruses
1.    Boot Sector Virus: This type of virus infects the master boot record. It is challenging and a complex task to remove this virus and often requires the system to be formatted. Mostly it spreads through removable media.
2.   Multipartite Virus: This type of virus spreads through multiple ways. It infects both the boot sector and executable files at the same time which allows them to act quickly and spread rapidly.
3.    Polymorphic Virus: These types of viruses are difficult to identify with a traditional anti-virus program. This is because the polymorphic viruses alter its signature pattern whenever it replicates.
4.   Overwrite Virus: This type of virus deletes all the files that it infects. The only possible mechanism to remove is to delete the infected files and the end-user has to lose all the contents in it. Identifying the overwrite virus is difficult as it spreads through emails.
5.    Macro viruses: As the name suggests, the macro viruses particularly target macro language commands in applications like Microsoft Word. The same is implied on other programs too.

  1. File Virus: This type of virus infects executable program files i.e. files with and .EXE.
  2. Stealth Virus: This type of virus is written in a way so as to avoid detection by standard anti-virus software.
    Examples of Viruses
    Some of the known viruses are:
    a.    Trojan horse virus
    b.    Sleeper
    c.     Logic bomb
    d.    Christmas virus
    e.     Jerusalem virus
    f.     Alabama virus
    g.    Code Red
    h.     I love you
    i.      Creeper virus
    j.     Stone
    k.     November 17 e.t.c.
    Sources of Virus
    These are the means through which viruses could be spread from one system to the other.
    i.      Infected memory devices
    ii.    E-mails attachments
    iii.    Internet downloads
    iv.    Infected CD-ROMs
    v.     Illegal duplication of software/cracked software
    Virus warning signs
    Some of the virus warning signs are listed below
    i.     Slowing down of response time
    ii.    Presence of tiny dots
    iii. Wandering cursor across the screen
    iv. Incomplete saving of file
    v.    Corruption of the system set-up instruction
    vi. Appearance of strange characters
    vii.  Insufficient memory space in a hard disk when you have enough memory space
    Virus Detection (Anti-Virus)
    Anti-viruses are also written programs by software developers to stop and curb the spread of virus in a system. Antivirus software is a type of utility software used for scanning and removing viruses from your computer. Once an anti-virus is installed on a system, it will be hard for a virus to enter the system except if the antivirus is outdated. All antivirus can be updated on the internet.
    Examples of antivirus are:
    a.    Norton Anti-virus
    b.    McAfee
    c.    AVG
    d.    Dr. Solomon’s Tool Kit
    e.    Penicillin
    f.     Avast
    g.    Windows defender
    Other Virus preventive measures include:
    1.    Timely update of operating system.
    2.    Timely update of antivirus software
    3.    Installation of only trusted or licensed software
    4.    Exercise care when browsing the internet