1. VIRUS Jan Damsgaard Dept. of Informatics Copenhagen Business School http://www.cbs.dk/staff/damsgaard/

2. EBUSSJan Damsgaard, 20042 Virus u In general a virus is a computer program that is perceived as “bad” –Just like certain weeds in the garden u Levels of Virus damage –Annoying – display messages on your screen –Harmless – prevents programs from operating –Harmful – Destroys data for the infected program –Destructive – destroys all data, prevents operation

3. EBUSSJan Damsgaard, 20043 5 Basic Types u Boot sector virus –Executes whenever the computer boots u Executable Virus –Execute whenever a program is called u Macro Virus or email virus –Dedicated meta-language instructions. E.g. Word u Worms –Can copy itself from machine to machine over a network u Trojan horses –Ordinary (useful) programs with a hidden (bad) intent

8. EBUSSJan Damsgaard, 20048 Meet a Worm called Code Red u Replicated itself 250,000 times in 9 hours on July 19, 2001 u Designed to do three things –Replicate itself for the first 20 days of each month –Replace web pages on infected servers with “hacked by Chinese” –Launch a concerted attack on the White House web server (100 connections to port 80)

9. Meet the even more vicious Nimda u Hit on Tuesday Sept. 18 2001 u It slowed the Internet down worldwide u A combination of code red, code blue, Apost, and Magisr.B –Infects web servers –infects web pages on that server –infects browsers that visit that homepage –executes automatically due to flaw in IE –sends out emails in your name

10. EBUSSJan Damsgaard, 200410 Virus Protection u Scanner –Scans all files on a local hard disk u Shield –Looks for virus in communication (downloads, floppy disks) u Cleaner –Removes the identified virus u Download definition file frequently!

11. EBUSSJan Damsgaard, 200411 The king of them all - yourself u Hoax Virus and chain letters –If you have a certain file on your computer you have already been infected. So therefore delete it immediately. Causes the file system to break down. u Comparable to witch hunts and burnings in the dark ages –Urban legends visit www.urbanlegends.com

12. EBUSSJan Damsgaard, 200412 SULFNBK.EXE Dear Friends, We have been unwittingly just infected with a virus from someone's email. THIS Klez Worm VIRUS SENDS ITSELF TO ALL THE ADDRESSES IN THE ADDRESS BOOK OF THE COMPUTER IT HAS ARRIVED AT. Take the time and remove it now. The instructions are easy and I got rid of it in a few minutes. Some versions of anti virus software including Norton and Inoculate T have not been able to detect it. It is said that the virus HIDES in the computer for 2 weeks and then DAMAGES THE DISC IRREPARABLY. The virus is called sulfnbk.exe Many apologies for the trouble it is causing. 1. Go to "Start" and click on "Find" 2. In the box, "find files or folders" type in sulfnbk.exe (the name of the virus) 3. Make sure you are searching in the C-drive (check in the box marked "Search in") 4. Click on Find 5. If the file is found you will find an ugly black icon with the name sulfnbk.exe This file is a program. DO NOT OPEN IT !!!!!! 6. Click on the RIGHT button of the mouse, on the file name, and then click on DELETE with the LEFT BUTTON OF THE MOUSE. 7. You will be asked to send this file to the recycle bin or wastebasket---respond YES 8. Open the recycle bin and eliminate the file, manually or by emptying the entire recycle bin or wastebasket. 9. If you do find this virus in your computer, send this email to all the people in your address book because the virus is transmitted in this way. (Even if you don't find the virus, you should probably still send this email to all your addresses) 10. I thought this was a joke at first but it is not and we found the ugly icon when we followed the above directions. Good luck.