VIRUS !!!!
COMPUTER VIRUS
What is a Virus / Computer Virus ?
A computer virus is a computer program that can copy itself and infect a computer without permission or knowledge of the user.
What exactly a virus can do ?
The original virus may modify the copies, or the copies of infected files may modify themselves.
How does a virus spread ?
A virus can only spread from one computer to another when its host is taken to the uninfected computer, for instance by a user sending it over a network or the Internet, or by carrying it on a removable medium such as a floppy disk, CD , or USB Drive. Meanwhile viruses can spread to other computers by infecting files on a network file system or a file system that is accessed by another computer.
When was the first such “Virus / Program” detected or created? By Whom ?
The Creeper virus was first detected on ARPANET, the forerunner of the Internet in the early 1970s. It spread via the TENEX operating system and could make use of any connected modem to dial out to remote computers and infect them. It would display the message “I’M THE CREEPER : CATCH ME IF YOU CAN.”.
The first major PC virus was a boot sector virus called Brain. It was created by Farooq Alvi Brother from Lahore Pakistan, in the year 1986. Actually the brothers created a program to stop creating copies of software which they wrote. However it was later named as a virus since it was infecting the boot sector of a machine and was causing damage to it.
Brain affected the 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 three kibibytes of bad sectors. The disk label is changed to Brain, and the following text can be seen in infected boot sectors:
Welcome to the Dungeon (c) 1986 Brain & Amjads (pvt) Ltd VIRUS_SHOE RECORD V9.0 Dedicated to the dynamic memories of millions of viruses who are no longer with us today – Thanks GOODNESS!! BEWARE OF THE er..VIRUS : this program is catching program follows after these messages….$#@%$@!!
Welcome to the Dungeon (c) 1986 Basit * Amjad (pvt) Ltd. BRAIN COMPUTER SERVICES 730 NIZAM BLOCK ALLAMA IQBAL TOWN LAHORE-PAKISTAN PHONE: 430791,443248,280530. Beware of this VIRUS…. Contact us for vaccination…
How does a virus affect my system ?
In order to work, a virus must be permitted to execute code and write to memory. This is the reason, many viruses attach themselves to executable files that may be part of legal programs. When user tries to run the infected program, the virus’ code may be executed first and then the original program starts.
What are the types of virus ?
Depending on the behavior and functionality the virus are divided in two categories
A) Resident Viruses
B) Non Resident Viruses
A) Resident Viruses
A type of computer virus that stores itself within memory allowing it to infect files instantaneously and does not require the user to run the file to infect files..
B) Non Resident Viruses :
A type of computer virus that does not store or execute itself from the computer memory. Executable viruses are an example of a non resident virus.
