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PRESENTED BY31. Amanpreet Kaur
32. Akshata Sabbani
33. Dashmeet Singh
34. Ranjit Kaur Sahota
35. Punit kaur Saini
36. Rajpreet Kaur Saini
WHAT IS COMPUTER VIRUS?
A computer virus is a computer program that can replicate itself and spread from one computer to another.
A computer virus is an executable program.
Depend on the nature of a virus, it may cause damage of your hard disk contents, and/or interfere normal operation of your computer.
HOW DOES A VIRUS SPREAD?
There are many ways in which computer viruses spread.• Through removable media like floppy disks,
CD's, DVD's, Flash memory pens etc. • Through the computer network (LAN, WAN,
etc...) via its various services like file sharing systems
• Internet via Email, web services and other files sharing services in chat and IM.
• It can infect an entire network that is connected to the internet.
VIRUSES
A virus is a small piece ofsoftware that piggybacks
onreal programs.
2 main characteristics of viruses It must execute
itself. It must replicate
itself. • Virus might attach itself
to a program such as spreadsheet.
• Each time the spreadsheet program runs, the virus runs too and replicate itself.
COMPUTER VIRUS DEFINED
A computer virus is defined as:
A program that can infect other programs by modifying them to include a possibly evolved copy of itself
Key Property: the ability to infect other programs.
TYPES OF COMPUTER VIRUSES
Computer viruses have made their mark on the PC's since the 90's with different types of viruses causing damage to computers. The different types of computer viruses areBoot sector Record Computer VirusProgram/File infector computer virus Macro Computer VirusOther Types of Viruses
• Multi-Partite Viruses• Polymorphic Viruses• Stealth Viruses• Script Viruses• ActiveX & Java Applets
Boot sector is that area of the computer that is accessed when the computer is turned on.
Damage Caused
Boot sector viruses gain complete control of the master boot record or the DOS boot sector by replacing the operating
system contents with that of its own.
RemovalThe best way to remove boot sector virus is to boot the computer with using a clean boot disk and then rewrite the files with the good operating system files on the infected disk.
Boot sector Record Computer Virus
PROGRAM/FILE INFECTOR COMPUTER VIRUS
This virus infects which contain code that can be executed and usually this virus infects files that can execute code like .exe, .com, .drv, .dll, .bin, .ovl
Damage CausedThe File infector virus can cause irreversible damage to files. By overwriting files it permanently destroys the content of these files.
RemovalThe only way to disinfect files from the file virus is that the files affected with the file virus have to be deleted and restoredfrom back up.
MACRO COMPUTER VIRUS
Macro is a set of commands written by the user to be executed, later. The different ways to create macros would be the macro recorder or Visual Basic for Applications.
Damage CausedSome common macros are •AutoExec •AutoNew •AutoOpen •AutoClose •AutoExit
RemovalPrevention is better than cure and the ways to prevent the virus from running is that the autoexec macro can be prevented from executing by starting word from command prompt.
Multi-partite virusesSome computer viruses appear to behave like many other viruses and sometimes more than one type. These are hybrids and are called as multi-partite computer viruses.
Polymorphic virusesThese viruses are written such that it changes its code when ever it passes to another machine.
Stealth virusesThe stealth virus uses techniques to avoid detection by redirecting the disk head to read another sector or alter the file size shown in the directory listing.
script virusesA subset of file viruses these are written in a variety of script languages like javascript, VBS, BAT, PHP etc… They are also able to infect other file formats such as HTML.
Active x & java appletsActive X and java controls are being used in web browsers to enable and disable sound or video and a host of other controls.
Other Types of Viruses
REMOVAL OF A VIRUS
• Removal of a virus depends on detection
• Detection is not decidable
• The removal of a virus is not absolutely guaranteed
• Therefore not all viruses can be precisely detected and removed from a given computer system.
REMOVAL OF A VIRUS
• If a more liberal detection method is used then detection and removal is possible
• But at the expense of producing false positives and false negatives.
• Ex. Erase all files created after a specific date from the system.
TIPS TO PREVENT COMPUTER VIRUS
• Use antivirus software and keep it up-to-date.• Install security patches.• Use a firewall. • Secure your browser. • Take control of your email. • Treat IM suspiciously. • Avoid P2P and distributed file sharing. • Keep abreast of Internet scams. • Don't fall victim to virus hoaxes.
TIPS TO PREVENT COMPUTER VIRUS
• Install protection tools • Periodic virus scanning • Handle email attachment carefully • NOT TO FORWARD Hoax messages to anyone. • Screen all transport media of virus/worm• Learn about hoaxes• Do not use illegal software
CONCLUSION
Be aware of the new infections out there.Take precaution measures.Always backup your data.Keep up-to-date on new Anti virus software.Simply avoid programs from unknown sources.
