Computer Virus

COMPUTER VIRUSES Cateye <1>WHAT IS A COMPUTER VIRUS: The term usually used to define a computer virus is: \' A computer virus is often malicious software which replicates itself\' [ Podell 1987 for similar definition ] - COMPUTER VIRUSES ARE BASICALLY PROGRAMS, LIKE A SPREADSHEET OR A WORD PROCESSOR. - PROGRAMS WHICH CAN INSERT EXECUTABLE COPIES OF ITSELF INTO OTHER PROGRAMS. - PROGRAMS THAT MANIPULATES PROGRAMS, MODIFIES OTHER PROGRAMS AND REPRODUCE ITSELF IN THE PROCESS. Comparing Biological viruses & Computer viruses ************************************************************* * Attack specific * Attack specific * * body cells * programs (*.COM *.EXE) * ************************************************************* * Modify the genetic information * Manipulate the program: * * of a cell other than previous 1* It performs tasks * ************************************************************* * New viruses grow in the * The infected program produces * * infected cell itself * virus programs * ************************************************************* * Infected cells aren\'t infected * Program are infected only once* * more than once by the same cell* by most programs* ************************************************************* * An infected organism may not * The infected program can work * * exhibit symptoms for a while * without error for a long time * ************************************************************* * Not all cells with which the * Program can be made immune * * virus contact are infected * against certain viruses * ************************************************************* * Viruses can mutate and thus * Virus program can modify * * cannot be clearly told apart * themselves & possibly escape * * * detection this way * ************************************************************* However, " computer virus " is just another name for a class of programs. They can do anything that another program can. The only distinguishing characteristic is the program has ability to reproduce and infect other programs. <2>WHAT KIND OF PROGRAM ARE CHARACTERIZED AS A VIRUS PROGRAM: - PROGRAM WHICH HAS CAPABILITY TO EXECUTE THE MODIFICATION ON A NUMBER OF PROGRAMS. - CAPABILITY TO RECOGNIZE A MODIFICATION PERFORMED ON A PROGRAM.(THE ABILITY TO PREVENT FURTHER MODIFICATION OF THE SAME PROGRAM UPON SUCH RECONDITION.) - MODIFIED SOFTWARE ASSUME ATTRIBUTES 1 TO 4. <3>HOW DOES A VIRUS SPREAD: A computer virus can only be put into your system either by yourself or someone else. One way in which a virus can be put into your computer is via a Trojan Horse. -TROJAN HORSE IS USUALLY CONTAMINATED IN DISKS WHICH ARE PARTICULARY PIRATED COPIES OF SOFTWARE. IT IS SIMPLY A DAMAGING PROGRAM DISGUISED AS AN INNOCENT ONE. MANY VIRUSES MAYBE HIDDEN IN IT, BUT T.H. THEMSELVES DO NOT HAVE THE ABILITY TO REPLICATE. Viruses also can be spread through a Wide Area network (WAN) or a Local Area Network (LAN) by telephone line. For example down loading a file from a local BBS. BBS(bulletin board system)-AN Electronic mailbox that user can access to send or receive massages. However, there seems to be countless numbers of ways to become infected. Every-time you down loads a program from somewhere or borrowed a disk from a friend, you are taking a risk of getting infected. <4>DAMAGES AND SIGNS OF INFECTION: a.> Fill Up your P.C. with Garbage: As a virus reproduces, it takes up space. This space cannot be used by the operator. As more copies of the virus are made, the memory space is lessened. b.> Mess Up Files: Computer files have a fixed method of being stored. With this being the case, it is very easy for a computer virus to affect the system so some parts of the accessed files cannot be located. c.> Mess Up FAT: FAT(the File Allocation Table) is the method used to contain the information required about the location of files stored on a disk. Any allocation to this information can cause endless trouble. d.> Mess Up The Boot Sector: The boot sector is the special information found on a disk. Changing the boot sector could result in the inability of the computer to run. e.> Format a Disk/ Diskette: A virus can simply format a disk as the operator would with the format or initialise command. f.> Reset The Computer: To reset the computer, the operator or the user only has to press a few keys. The virus can do this by sending the codes to the operating system. g.> Slowing Things Down: As the name