Malware

Malware is malicious software that has been designed to infiltrate or damage a computer system. The effects of malware can range from mere frustration to serious problem that require a lot of time & money to fix. Some common types of malware include computer viruses, worms & Trojan horses. A computer virus is a self-replicating program that spreads by inserting copies of itself into documents or other programs. The insertion of a virus into the document or programs is called an infection, and the infected file is called a host. A virus spreads from one computer to another when its host is transferred to an uninfected computer, for instance when a user sends it over a network or carries it on a removable medium such as floppy disk. Viruses can also spread to other computers by infecting files on a network file system or on a file system accessed by another computer. Although some viruses can be destructive, for example by deleting or destroying data, many are fairly benign or simply annoying. The uncontrolled self-replication, which wastes or overwhelms computer resources (memory, disk space, etc.), is the main negative effect of viruses.

A computer worm is a seld-replicating computer program, similar to a virus. Unlike a virus, however, a worm does not need a host to spread. A worm uses a network to send copies itself to other computer systems. Although a worm can be prorgammed to damage files on a computer, more often it harms the network by consuming bandwidth & slowing it down. Viruses generally do not affect network performance as their malicious activities are mostly confined within the target computer.

A Trojan horse ia any program that invites the user to run it, but conceals a harmful purpose. It pretends to do something useful or interesting while causing damage. A Trojan horse is technically a normal computer program. It cannot replicate & spread by itself, nor is it able to function on its own. It needs to deceive the computer user into allowing it to perform actions such as deleting the user's files or installing other harmful software. This may occur when the user opens an e-mail or e-mail attachment, or visits a malicious website. the software installed by a Trojan Horse often includes prorgams that record & send valuable information, such as the user's passwords or credit card numbers, to the creator of the Trojan horse. Trojan horses can also install programs that make a computer send out unsolicited e-mails, which may include advertisements & other malware.