A malicious program that transfers from one computer to another by any type of means

Macro Virus: These type of virus infects word, excel, PowerPoint, access and other data files. Once infected repairing of these files is very much difficult.

Master boot record files: MBR viruses are memory-resident viruses and copy itself to the first sector of a storage device which is used for partition tables or OS loading programs .A MBR virus will infect this particular area of Storage device instead of normal files. The easiest way to remove a MBR virus is to clean the MBR area,

Boot sector virus: Boot sector virus infects the boot sector of a HDD or FDD. These are also memory resident in nature. As soon as the computer starts it gets infected from the boot sector. Cleaning this type of virus is very difficult.

Multipartite virus: A hybrid of Boot and Program/file viruses. They infect program files and when the infected program is executed, these viruses infect the boot record. When you boot the computer next time the virus from the boot record loads in memory and then start infecting other program files on disk

Polymorphic viruses: A virus that can encrypt its code in different ways so that it appears differently in each infection. These viruses are more difficult to detect.

Stealth viruses: These types of viruses use different kind of techniques to avoid detection. They either redirect the disk head to read another sector instead of the one in which they reside or they may alter the reading of the infected file’s size shown in the directory listing. For example, the Whale virus adds 9216 bytes to an infected file; then the virus subtracts the same number of bytes (9216) from the size given in the directory.

toreplicateitselfandtransferfromonecomputertoanother(internet,localnetworks,FDs,CDs,etc.)

b.Worm– amaliciousprogramthattransfersfromonecomputertoanotherbyanytypesofmeans.Ex.ILOVEYOUWormInternetThreats:

InternetThreats:c.Trojan– amaliciousprogramthatdisguisesasausefulprogrambutoncedownloadedorinstalled,leavesyourPCunprotectedandallowshackerstogetyourinformation.

InternetThreats:d.Spyware– aprogramthatrunsinthebackgroundwithoutyouknowingit(thuscalled“spy”). It has theability to monitorwhatyouarecurrentlydoingandtypingthroughkeylogging.