Computer Worm

A computer worm is a self-replicating computer program. It uses a network to send copies of itself to other nodes (computers on the network) and it may do so without any user intervention. Unlike a virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, if only by consuming bandwidth, whereas viruses almost always corrupt or devour files on a targeted computer.

Virus Classification

Virus classification involves naming and placing viruses into a taxonomic system. Like the relatively consistent classification systems seen for cellular organisms, virus classification is the subject of ongoing debate and proposals. This is largely due to the pseudo-living nature of viruses, which are not yet definitively living or non-living. As such, they do not fit neatly into the established biological classification system in place for cellular organisms, such as eukaryotes and prokaryotes.

Virus classification is based mainly on phenotypic characteristics, including morphology, nucleic acid type, mode of replication, host organisms, and the type of disease they cause. A combination of two main schemes is currently in widespread use for the classification of viruses. David Baltimore, a Nobel Prize-winning biologist, devised the Baltimore classification system, which places viruses into one of seven groups. These groups are designated by Roman numerals and separate viruses based on their mode of replication, and genome type. Accompanying this broad method of classification are specific naming conventions and further classification guidelines set out by the International Committee on Taxonomy of Viruses.

History Of Anti Virus

There are competing claims for the innovator of the first antivirus product. Possibly the first publicly documented removal of a computer virus in the wild was performed by Bernt Fix in 1987.
ClamTk 4.08 virus scanner running on Ubuntu 9.04An antivirus program to counter the Polish MKS vir was released in 1987. Dr. Solomon's Anti-Virus Toolkit, AIDSTEST and AntiVir were released by in 1988. Dr. Ahn Chul Soo (Charles Ahn, founder of AhnLab Inc) in South Korea also released the antivirus software called 'Vaccine Ⅰ' in June 10, 1988By late 1990, nineteen separate antivirus products were available including Norton AntiVirus and McAfee VirusScan. Early contributors to work on computer viruses and countermeasures included Fred Cohen, Peter Tippett, John McAfee and Ahn Chul Soo.Before Internet connectivity was widespread, viruses were typically spread by infected floppy disks. Antivirus software came into use, but was updated relatively infrequently. During this time, virus checkers essentially had to check executable files and the boot sectors of floppy and hard disks. However, as internet usage became common, initially through the use of modems, viruses spread throughout the Internet.Powerful macros used in word processor applications, such as Microsoft Word, presented a further risk. Virus writers started using the macros to write viruses embedded within documents. This meant that computers could now also be at risk from infection by documents with hidden attached macros as programs.Later email programs, in particular Microsoft Outlook Express and Outlook, were vulnerable to viruses embedded in the email body itself. Now, a user's computer could be infected by just opening or previewing a message. This meant that virus checkers had to check many more types of files. As always-on broadband connections became the norm and more and more viruses were released, it became essential to update virus checkers more and more frequently. Even then, a new zero-day virus could become widespread before antivirus companies released an update to protect against it.

Computer Virus

A computer virus is a computer program that can copy itself and infect a computer without the permission or knowledge of the owner. The term "virus" is also commonly but erroneously used to refer to other types of malware, adware, and spyware programs that do not have the reproductive ability. A true virus can only spread from one computer to another (in some form of executable code) when its host is taken to the target computer; for instance because a user sent it over a network or the Internet, or carried it on a removable medium such as a floppy disk, CD, DVD, or USB drive. Viruses can increase their chances of spreading to other computers by infecting files on a network file system or a file system that is accessed by another computer.

The term "computer virus" is sometimes used as a catch-all phrase to include all types of malware. Malware includes computer viruses, worms, trojan horses, most rootkits, spyware, dishonest adware, crimeware, and other malicious and unwanted software), including true viruses. Viruses are sometimes confused with computer worms and Trojan horses, which are technically different. A worm can exploit security vulnerabilities to spread itself to other computers without needing to be transferred as part of a host, and a Trojan horse is a program that appears harmless but has a hidden agenda. Worms and Trojans, like viruses, may cause harm to either a computer system's hosted data, functional performance, or networking throughput, when they are executed. Some viruses and other malware have symptoms noticeable to the computer user, but many are surreptitious.

Most personal computers are now connected to the Internet and to local area networks, facilitating the spread of malicious code. Today's viruses may also take advantage of network services such as the World Wide Web, e-mail, Instant Messaging, and file sharing systems to spread.

Virus

A virus (from the Latin virus meaning toxin or poison) is a microscopic infectious agent that can reproduce only inside a host cell. Viruses infect all types of organisms: from animals and plants, to bacteria and archaea. Since the initial discovery of tobacco mosaic virus by Martinus Beijerinck in 1898, more than 5,000 types of virus have been described in detail, although most types of virus remain undiscovered. Viruses are ubiquitous, as they are found in almost every ecosystem on Earth, and are the most abundant type of biological entity on the planet. The study of viruses is known as virology, and is a branch of microbiology.

Viruses consist of two or three parts: all viruses have genes made from either DNA or RNA, long molecules that carry genetic information; all have a protein coat that protects these genes; and some have an envelope of fat that surrounds them when they are outside a cell. Viruses vary in shape from simple helical and icosahedral shapes, to more complex structures. They are about 1/100th the size of bacteria. The origins of viruses in the evolutionary history of life are unclear: some may have evolved from plasmids—pieces of DNA that can move between cells—while others may have evolved from bacteria. In evolution, viruses are an important means of horizontal gene transfer, which increases genetic diversity.

Viruses spread in many ways; plant viruses are often transmitted from plant to plant by insects that feed on sap, such as aphids, while animal viruses can be carried by blood-sucking insects. These disease-bearing organisms are known as vectors. Influenza viruses are spread by coughing and sneezing, and others such as norovirus, are transmitted by the faecal-oral route, when they contaminate hands, food, or water. Rotaviruses are often spread by direct contact with infected children. HIV is one of several viruses that are transmitted through sexual contact.

Not all viruses cause disease, as many viruses reproduce without causing any obvious harm to the infected organism. Viruses such as hepatitis B can cause life-long or chronic infections, and the viruses continue to replicate in the body despite the hosts' defence mechanisms. In some cases, these chronic infections might be beneficial as they might increase the immune system's response against infection by other pathogens. However, in most cases viral infections in animals cause an immune response that eliminates the infecting virus. These immune responses can also be produced by vaccines that give immunity to a viral infection. Microorganisms such as bacteria also have defences against viral infection, such as restriction modification systems. Antibiotics have no effect on viruses, but antiviral drugs have been developed to treat both life-threatening and more minor infections. Unlike antibiotics however, antiviral drugs do not destroy their target pathogen but inhibit their development. Any drug that destroys viruses is called a viricide.

Virus Hoax

A computer virus hoax is a message warning the recipient of a non-existent computer virus threat. The message is usually a chain e-mail that tells the recipient to forward it to everyone they know.Most hoaxes are sensational in nature and easily identified by the fact that they indicate that the virus will do nearly impossible things, like blow up the recipient's computer and set it on fire, or less sensationally, delete everything on the user's computer. They often include announcements claimed to be from reputable organizations such as Microsoft, IBM, or news sources such as CNN and include emotive language and encouragement to forward the message. These sources are quoted in order to add credibility to the hoax.

Virus hoaxes are usually harmless and accomplish nothing more than annoying people who identify it as a hoax and waste the time of people who forward the message. Nevertheless, a number of hoaxes have warned users that vital system files are viruses and encourage the user to delete the file, possibly damaging the system. Examples of this type include the jdbgmgr.exe virus hoax and the SULFNBK.EXE hoax.

Some consider virus hoaxes and other chain e-mails to be a computer worm in and of themselves. They replicate by exploiting users' ignorance or emotional responses.

Hoaxes are not to be confused with computer pranks. Computer pranks are programs that perform unwanted and annoying actions on a computer, such as randomly moving the mouse.

Computer Worm

A computer worm is a self-replicating computer program. It uses a network to send copies of itself to other nodes (computers on the network) and it may do so without any user intervention. Unlike a virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, if only by consuming bandwidth, whereas viruses almost always corrupt or devour files on a targeted computer.