Computer Viruses


(anonymous)

<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.


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 implies, the object of the virus is to slow down
the running line of the program.

h.> Redefine Keys:
The computer has been program to recognize that certain
codes/ signals symbolize a certain keystroke. The virus
could change the definition of these keystrokes.

i.> Lock The Keyboard: redefining all keys into an empty key.

<5>WHAT TO DO AFTER VIRUS ATTACKS:
When signs of a virus attack have been recognized,
the virus has already reproduced itself several times.
Thus, to get rid of the virus, the user has to hack down
and destroy each one of these copies. The easier way is to:

1. Have the original write protected back-up copy of your
operating system on a diskette.
2. Power down the machine.
3. Boot up the system from the original system diskette.
4. Format the hard disk.
5. Restore all back-ups and all executable program.

*If it\'s not effective, power down and seek for professional help*

<6> TYPE OF VIRUSES:
a.> OVER-WRITING VIRUSES

b.> NON-OVERWRITNG VIRUSES

c.> MEMORY RESENDENT VIRUSES

<7>PRACTICE SAFE HEX:
Viruses are a day to day reality. Different activities