Memory Resident Virus
These viruses fix themselves in the computer memory and get activated whenever the OS runs and infects all the files that are then opened.
Hideout: This type of virus hides in the RAM and stays there even after the malicious code is executed. It gets control over the system memory and allocate memory blocks through which it runs its own code, and executes the code when any function is executed.
Target: It can corrupt files and programs that are opened, closed, copied, renamed, etc.
Examples: Randex, CMJ, Meve, and MrKlunky
Protection: Install an antivirus program.
Hideout: This type of virus hides in the RAM and stays there even after the malicious code is executed. It gets control over the system memory and allocate memory blocks through which it runs its own code, and executes the code when any function is executed.
Target: It can corrupt files and programs that are opened, closed, copied, renamed, etc.
Examples: Randex, CMJ, Meve, and MrKlunky
Protection: Install an antivirus program.
Overwrite Viruses
A virus of this kind is characterized by the fact that it deletes the information contained in the files that it infects, rendering them partially or totally useless once they have been infected.
Hideout: The virus replaces the file content. However, it does not change the file size.
Examples: Way, Trj.Reboot, Trivial.88.D
Protection: The only way to clean a file infected by an overwrite virus is to delete the file completely, thus losing the original content.
However, it is very easy to detect this type of virus, as the original program becomes useless.
Hideout: The virus replaces the file content. However, it does not change the file size.
Examples: Way, Trj.Reboot, Trivial.88.D
Protection: The only way to clean a file infected by an overwrite virus is to delete the file completely, thus losing the original content.
However, it is very easy to detect this type of virus, as the original program becomes useless.
Boot Sector Virus
This type of virus affects the boot sector of a hard disk. This is a crucial part of the disk, in which information of the disk itself is stored along with a program that makes it possible to boot (start) the computer from the disk. This type of virus is also called Master Boot Sector Virus or Master Boot Record Virus.
Hideout: It hides in the memory until DOS accesses the floppy disk, and whichever boot data is accessed, the virus infects it.
Examples: Poly boot.B, AntiEXE
Protection: The best way of avoiding boot sector viruses is to ensure that floppy disks are write-protected. Also, never start your computer with an unknown floppy disk in the disk drive.
Hideout: It hides in the memory until DOS accesses the floppy disk, and whichever boot data is accessed, the virus infects it.
Examples: Poly boot.B, AntiEXE
Protection: The best way of avoiding boot sector viruses is to ensure that floppy disks are write-protected. Also, never start your computer with an unknown floppy disk in the disk drive.
Macro Virus
Macro viruses infect files that are created using certain applications or programs that contain macros, like .doc, .xls, .pps, .mdb, etc. These mini-programs make it possible to automate series of operations so that they are performed as a single action, thereby saving the user from having to carry them out one by one. These viruses automatically infect the file that contains macros, and also infects the templates and documents that the file contains.
Hideout: These hide in documents that are shared via e-mail or networks.
Examples: Relax, Melissa.A, Bablas, O97M/Y2K
Protection: The best protection technique is to avoid opening e-mails from unknown senders. Also, disabling macros can help to protect your useful data.
Hideout: These hide in documents that are shared via e-mail or networks.
Examples: Relax, Melissa.A, Bablas, O97M/Y2K
Protection: The best protection technique is to avoid opening e-mails from unknown senders. Also, disabling macros can help to protect your useful data.
Directory Virus
Directory viruses (also called Cluster Virus/File System Virus) infect the directory of your computer by changing the path that indicates the location of a file. When you execute a program file with an extension .EXE or .COM that has been infected by a virus, you are unknowingly running the virus program, while the original file and program is previously moved by the virus. Once infected, it becomes impossible to locate the original files.
Hideout: It is usually located in only one location of the disk, but infects the entire program in the directory.
Examples: Dir-2 virus
Protection: All you can do is, reinstall all the files from the backup that are infected after formatting the disk.
Hideout: It is usually located in only one location of the disk, but infects the entire program in the directory.
Examples: Dir-2 virus
Protection: All you can do is, reinstall all the files from the backup that are infected after formatting the disk.
Worms
A worm is a program very similar to a virus; it has the ability to self-replicate and can lead to negative effects on your system. But they can be detected and eliminated by an antivirus software.
Hideout: These generally spread through e-mails and networks. They do not infect files or damage them, but they replicate so fast that the entire network may collapse.
Examples: PSWBugbear.B, Lovgate.F, Trile.C, Sobig.D, Mapson
Protection: Install an updated version of antivirus
Hideout: These generally spread through e-mails and networks. They do not infect files or damage them, but they replicate so fast that the entire network may collapse.
Examples: PSWBugbear.B, Lovgate.F, Trile.C, Sobig.D, Mapson
Protection: Install an updated version of antivirus