Some Computer Viruses In History

Some Computer Viruses In History



Some Computer Viruses In History
Computer viruses generally trick hosts or​ other types of​ computers into reproducing copies of​ the​ invading organism .​
They spread from computer to​ computer through electronic bulletin boards,​ telecommunication systems and shared floppy disks .​
Viruses are created by human programmers,​ for fun or​ malice,​ but once they begin to​ spread they take on​ a​ life of​ their own,​ creating disruption,​ dismay and paranoia in​ their wake.
If the​ virus is​ found in​ any of​ the​ PC's that PC should immediately be isolated .​
The virus can be removed by giving an​ antidote by studying the​ virus .​
The machine should be put into use only after the​ virus is​ eliminated.
Viruses and such
A Virus is​ defined as​ a​ program inserted into another program .​
It gets activated by its host program .​
It replicates itself and spreads to​ others through floppy transfer .​
a​ virus infects data or​ program every time the​ user runs the​ infected program and the​ virus takes advantages and replicates itself.
There are two types of​ computer viruses 'parasitic' and 'boot' virus.
A Parasitic virus attaches itself to​ other programs and is​ activated when the​ host program is​ executed .​
It tries to​ get attached to​ more programs so that chances of​ getting activated is​ more .​
It spreads to​ other computers when the​ affected programs are copied .​
'Jerusalem' and 'Datacrime' are parasitic viruses.
A Boot virus is​ designed to​ enter the​ boot sector of​ a​ floppy disc .​
It works by replacing the​ first sector on​ the​ disc with part of​ itself .​
It hides the​ rest of​ itself elsewhere on​ the​ disc,​ with a​ copy of​ the​ first sector .​
The virus is​ loaded by the​ computers built-in start-up program when the​ machine is​ switched on​ .​
The virus loads,​ installs itself,​ hides the​ rest of​ itself and then loads the​ original program .​
On a​ hard disc,​ virus can occupy DOS boot sector or​ master boot sector.
Some Reported Viruses
C-Brain: Amjad and Basit,​ two pakistani brothers,​ developed this software in​ January 1986 to​ discourage people from buying illegal software at​ throwaway prices .​
This was the​ most famous virus ever found and has a​ record of​ damaging few millions of​ personal computers .​
This is​ designed to​ stay in​ the​ boot sector of​ the​ disc or​ near zero sector .​
The virus enters the​ machine memory once the​ PC is​ booted with the​ infected floppy.
Macmag: This virus attacked Apple Macintosh computers only .​
Not much damage is​ reported because of​ this virus .​
This was not noticed on​ any IBM compatible PCs .​
It displayed a​ message of​ peace on​ the​ monitor and killed itself.
Cascade: This virus attacked IBM PCs and compatibles .​
The letters on​ the​ screen could be seen dropping vertically down to​ the​ bottom of​ screen after the​ virus picked them off in​ alphabetical order .​
This is​ a​ sort of​ parasitic virus .​
It attaches itself to​ other programs and gets activated when the​ host program is​ executed .​
It gets copied to​ other PCs when the​ programs are copied.
Jerusalem: Found in​ 1987 at​ Hebrew University,​ Jerusalem,​ this virus was designed to​ activate only on​ Friday,​ January 13 and delete all the​ files executed on​ that day .​
This infects the​ COM and EXE files .​
This is​ similar to​ Cascade virus in​ that it​ is​ parasitic in​ nature .​
This virus attaches itself to​ COM and EXE files to​ damage the​ data.
Daracrime/Columbus or​ October the​ 13th virus: This virus is​ similar to​ Jerusalem and was programmed to​ attack on​ October 13,​ 1989 .​
Track zero of​ computer hard disk is​ destroyed and the​ contents of​ discs are rendered unreadable .​
This virus enters COM and EXE files and damages the​ hard disk .​
An antidote called 'Vchecker' was developed by the​ American Computer Society .​
Fortunately the​ virus was located in​ March 1989 itself and the​ damage reported after October 13 was minimal.
Bomb: This is​ also know as​ 'Logic Bomb' and 'Time Bomb' .​
An event triggered routine in​ a​ program that causes a​ program to​ crash is​ defined as​ a​ 'bomb' .​
Generally,​ 'bomb' is​ a​ software inserted in​ a​ program by a​ person working in​ the​ company.




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