“A computer virus is a software program that attaches itself to or copies itself into another program on a computer. The purpose of the virus is to trick the computer into following instructions not intended by the original program developer. Users copy infected files from another computer on a network, from a flash drive, or from an online service. Alternatively, users can transport viruses from home and work on their portable computers, which have access to the Internet and other network services.
A computer virus acts in a similar fashion to a biological virus. It “infects” a host
program, and may cause that host program to replicate itself to other computers.
The virus cannot exist without a host, and it can spread from host to host in an
The first virus recorded was the Creeper virus, written by researcher Bob Thomas in
1971. The Creeper copied itself to other networked computers, displaying the message
“I’m the creeper, catch me if you can!” Thomas designed the virus as an experimental
self-replicating program to see how such programs would affect computers on a network.
Shortly after the Creeper virus was released, researchers unleashed the Reaper program
to find and eradicate the Creeper.
Today, thousands of known viruses infect programs of all types. The main concern
with viruses is that they often attach themselves to common programs. When users
run these infected programs, they are actually running virus code with their user
credentials and authorization. The virus doesn’t have to escalate privileges; the user
who runs the infected program provides the virus with his or her authenticated
credentials and permissions.
Over time, viruses have grown smarter. For example, some viruses can combat
malware-detection programs by disabling their detection functions. Others compensate
for the fact that files infected by a virus typically increase in size, making them relatively
easy to detect, by spoofing the pre-infected file’s size. That way, it appears nothing
has changed.” (Kim and Solomon, 2012)
Kim, D. and Solomon, M. (2012). Fundamentals of Information System Security, Jones & Bartlett Learning.
eText: ISBN-10 1-4496-4248-9
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