Boot
Sector Infectors: The boot program, you get a
boot sector virus by leaving an infected diskette in a drive and rebooting
the machine. When the boot sector program is read and executed, the virus
goes into memory and infects your hard drive.
File
Infectors: These are viruses that attach
themselves to, or replace .COM and EXE files.( in some cases they can infect
files with other extensions) File Infector virus' infect uninfected programs
when they are executed in memory. In other cases they are infected when they
are opened, occasionally the virus simply infects all of the files in the
directory it was run from. The file-infector class is also used to refer to
programs that do not physically attach to files but associate themselves with
program files names.
Master
Boot Record Infectors: Infects the
system's Master Boot Record on hard drives and the Boot Sector on floppy
diskettes. This type of virus takes control of the system at a low level;
activating between the system hardware and the operating system. A Boot
Sector virus is loaded into memory upon boot-up, before virus detection code
can be executed.
Macro
Virus: Some computer applications contain
macro languages to help automate tedious tasks. As computers have grown more
powerful, the tasks have become more complex. Some macro languages offer the
ability to write files other than the original document. This feature may be
used by virus authors to create unwanted macros, which "infect"
documents. Macro virus' are typically spread through MS Word & Excel
files.
| Multi-partite
Viruses: Multi-partite
viruses are a combination of the viruses listed above. |
cuted.
Polymorphic
viruses: They are coded in such a way that they infect a system and change
their signature.
Worms: Worms are
program that replicate and spread to other system.
| Trojans: A Trojan
is a program file that claims to do something but it actually does something
that is not required. |
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