viruseseffects and their Execution

1. Assignment
Submitted to: Ma’am Ayesha
Submitted by: Huma Tariq
Roll No: 14020204-050
Department:Computer Science
Topic:Viruses

2. Virus
Whatare virus?
An infective agent that typically consists of a nucleic acid molecule in a protein coat, is too
small to be seen by light microscopy, and is able to multiply only within the living cells of a
host. a piece of code which is capable of copying itself and typically has a detrimental
effect, such as corrupting the system or destroying data.
Effects of Virus?
 computer virus can slow down your computer.
 might corrupt your system files.
 might make some programs faulty or corrupt.
 might damage your boot sector creating problems when you boot into the windows.
 might steal important information from your computer and send to some other person.
 might change the power ratings of your computer and could blast the system.
Execution of Virus:
A virus can't execute itself, unless it has the cooperation of the Operating System and/or
software bugs and/or the user. If the OS allows files to be executed automatically because
of their name or location (for example an email attachment) then a virus can masquerade
as a legitimate file and be executed by the OS without user intervention. This used to be
the default behaviour in early email clients.
Also, if the OS or specific software has errors that a virus can exploit to run its code, then a
virus can start itself. Yes, in the context of the browser, since unintentionally you're
executing the page without clicking on anything. Such viruses are capable of downloading
themselves to your hard disk without your cooperation.The propagation vector here can
be JavaScript, Java, ActiveX, Flash and other plugins.
Many such attacks are carried out through cross-site scripting.One of its prorogation
methods was via open windows file shares. From memory, it copied itself as an .eml file to
open network shares. There is something called Silent Java drive by (SJDB) that can
download and install a virus when you just visit a web pages.The vast majority of viruses
target systems running Microsoft Windows. This is due to Microsoft's large market share
of desktop users.

3. The diversity of software systems on a network limits the destructive potentialof viruses
and malware.Open-source operating systems such as Linux allow users to choose from a
variety of desktop environments, packaging tools, etc., which means that malicious
codetargeting any of these systems will only affect a subset of all users. Many Windows
users are running the same set of applications, enabling viruses to rapidly spread among
Microsoft Windows systems by targeting the same exploits on large numbers of hosts.
Regenerationof virus:
Though most computerusers have learned to fear viruses, few really know what they are.
Viruses are programs that replicate themselves inside a computer. The malicious bug
cannot do its damage when a user simply surfs the Web or opens a plain text message
such as an e-mail. However, viruses are unleashed when they are hidden in attachments
to e-mail messages and someone opens that attachment. After viruses replicate, many
carry out damaging instructions that have been programmed intothem.Consistent with
the invention, systems and methods are provided for regenerating computerfiles on a
computer system having a computer with an operating system. The method includes
receiving an input from a user to specify monitored files, automatically detecting
modification of at least one of the monitored files, and automatically replacing the at least
one modified monitored file with a backup copy of the at least one modified monitored
file.