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COMPUTERS ( types of viruses)

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COMPUTERS ( types of viruses)

  1. 1. Index Acknowledgement What is a computer virus How a computer virus spreads First computer virus Types of computer viruses How to detect a virus How to prevent virus bibliography
  2. 2. Acknowledgement I would like to express my special thanks of gratitude to my teacher ms.Tasneem mam as well as our principal who gave me the golden opportunity to do this wonderful project on the topic types of viruses, which also helped me in doing a lot of Research and i came to know about so many new things I am really thankful to them. Secondly i would also like to thank my parents and friends who helped me a lot in finishing this project within the limited time. I am making this project not only for marks but to also increase my knowledge. THANKS AGAIN TO ALL WHO HELPED ME.
  3. 3. What is a computer virus? A computer virus is a type of malware that, when executed, replicates by inserting copies of itself (possibly modified) into other computer programs, data files, or the boot sector of the hard drive; when this replication succeeds, the affected areas are then said to be "infected". Viruses often perform some type of harmful activity on infected hosts, such as stealing hard disk space or CPU time, accessing private information, corrupting data. However, not all viruses carry a destructive payload or attempt to hide themselves. The vast majority of viruses (over 99%) target systems running Microsoft Windows, employing a variety of mechanisms to infect new hosts, and often using complex anti-detection/stealth strategies to evade antivirus software. Computer viruses currently cause billions of dollars worth of economic damage each year, due to causing systems failure, wasting computer resources, corrupting data, increasing maintenance costs, etc.
  4. 4. How a computer virus spreads? For a computer virus to spread through a computer system, or network, it must be activated. This means that the file that contains the virus must be opened, or executed in order for the virus to come to life. After it gets activated, these viruses look for certain programs to infect. The main and the important that you must note is that, all viruses seem to do well is duplicate themselves within the programs they find, and this is the main reason as to how they spread well. 1. Email attachments. 2. Rogue Websites. 3. Networks- If your computer is connected to a home network or if your work computer is part of a larger network, you may find yourself with an infection through no fault of your own. 4. Infected hard disks. 5. Hackers/fake Anti Virus Software 6. From Mobile Devices. 7. Friends and Relatives.
  5. 5. First computer virus Brain is the industry standard name for a computer virus that was released in its first form in January 1986 and is considered to be the first computer virus for MS-DOS. It infects the boot sector of storage media formatted with the DOS File Allocation Table (FAT) file system. Brain was written by two brothers, Basit Farooq Alvi and Amjad Farooq Alvi from Lahore, Pakistan. Brain affects the IBM PC computer by replacing the boot sector of a floppy disk with a copy of the virus. The real boot sector is moved to another sector and marked as bad. Infected disks usually have five kilobytes of bad sectors.
  6. 6. Types of computer viruses Trojan Horse A program written to deliver a malicious program that may then cause destruction to your computer. A Trojan horse is delivered by someone or hidden within another program that may seem harmless. Spyware A program written to monitor your actions on a computer. A common type of spyware is a key-logger program. This program can record every key stroke and mouse click you make. Spyware can be delivered via a Trojan horse program. Adware Adware is a form of malware. One word - pop-ups. Adware is designed to pop up advertisements. Adware can be very annoying. Worms Just a nasty little program to cause slowness in a network. A worm will replicate itself and spread from computer to computer. Worms are commonly spread through email attachments. Boot Sector Virus
  7. 7. Not so common anymore, but they were nasty little programs that got loaded into your master boot record. Most commonly spread by floppy disks. These viruses could then launch themselves before your operating system even loaded. Time Bomb A virus written to execute at a later date or upon an action performed. These programs lay dormant until an event occurs. Browser Hijacker A virus that will over take your web browser and automatically redirect you to another website. File Infector Virus A virus that lives within a file, typically a .exe file. When the file is executed, it will then run its nasty code. Polymorphic Virus A virus written to change itself in order to evade virus detection. Macro Virus A virus that hides itself inside of macros used by programs such as Microsoft Excel. Web Scripting Virus A virus that hides within a website. Some are put there on purpose, some get injected into websites that are not properly secured.
  8. 8. How to detect a Virus (signs of virus being infected) Signs of an infected computer can be numerous depending on which virus your computer is infected with. 1. My computer speaks to me. There are all types of pop-ups and messages on the desktop either advertising things, saying that the PC is infected and needs protection. 2. My computer is running extremely slowly. This could be a symptom of many things, including infection by a virus. If it has been infected by a virus, worm or Trojan, among other things, which are running on the computer, they could be running tasks that consume a lot of resources. 3. Applications won't start. Sometimes another program might even run. As in the previous case, this could be another type of problem, but at the very least it's a symptom that tells you that something is wrong. 4. I cannot connect to the Internet or it runs very slowly. Loss of Internet communication is another common symptom of infection, although it could also be due to a problem with your service provider or router.
  9. 9. 5. When I connect to the Internet, all types of windows open or the browser displays pages I have not requested. This is another certain sign of infection. Many threats are designed to redirect traffic to certain websites against the user’s will, and can even spoof Web pages. 6. My antivirus has disappeared, my firewall is disabled. Another typical characteristic of many threats is that they disable security systems installed on computers. Perhaps if one thing shuts down it might just be a specific software failure; but if all your security components are disabled. 7. Library files for running games, programs, etc. have disappeared from my computer. Once again, this could be a sign of infection, although it could also be down to incomplete or incorrect installation of programs. To check for viruses, scan your computer with an antivirus program. New viruses appear every day, so keeping your antivirus program updated is important.
  10. 10. How to prevent computer viruses 1. Install a reliable antivirus program From the first moment you turn your computer on, you should have a trusted anti virus program by your side. Even if you have a machine that isn’t hooked up to the Internet, a reliable anti virus program is a low cost and common sense addition to any machine 2. Avoid suspicious websites. A good virus protection program will alert you when you visit a website that attempts to install or run a program on your computer. Many less than reputable adult websites do this, so if you get a warning, don’t go back, you may end up with a bug you can’t get rid of. 3. Never Open Email Attachments Without Scanning Them First. The most common way viruses are spread throughout the Internet is still via email. Some attachments, like pictures, now display in emails and don’t require an attachment to be manually opened, but other documents do. 4. Set up Automatic Scans Many of the top anti virus programs, as well as the best anti- spyware programs, now have settings that will let them automatically run during down times or in the middle of the night.
  11. 11. 5. Know What To Look . Even if you are just a casual computer user, you should have an idea of how your machine operates, what normal pop up windows look like and what popular viruses are out there, that way, when your computer begins exhibiting tell tale signs, you’ll know. 6. Stay Away From Cracked Software. It is so secret that you can download illegal, cracked versions of some programs online. As tempting as it may be, these files are almost always infested with advanced and difficult to detect bugs. Play it safe and get your software from the source. 7. Install a Firewall A firewall is a program that screens incoming Internet and network traffic
  12. 12. Bibliography