Malware is software designed to harm computers and computer networks or to exploit (make use of) them without the owner’s consent. Malware is short for mal_icious soft_ware. Malware is generally copied to a computer without the user’s awareness. Malware may steal, encrypt (disguise), or delete data. It may hijack computer functions and spy on computer activity. Protecting computer systems against malware is a major concern in information technology.
Perhaps the best-known type of malware is the computer virus . A computer virus is a type of software that places a copy of itself within another computer program and can spread to other software after the infected application is run. A virus can be transferred from one computer to another via a computer network, the internet , or a storage device , such as a flash drive. A malicious virus may be used to change information in databases, rewrite sections of programs, or cause a computer to send data to other locations over a network.
Some other types of malicious software include Trojan horses and worms. A Trojan horse appears to be a useful program, but usually has a harmful purpose. It does not copy itself, but it may be used to steal passwords or to deliver a virus. A worm duplicates itself without attaching to other programs. It may thus congest a computer network by filling up storage space with copies of itself.
Some malware is used for purposes of vandalism or for computer-based terrorism (called cyberterrorism) or computer-based warfare, called cyberwarfare . Other malware is used to make criminal profit. Malware called adware downloads and displays advertisements without the user’s permission. Spyware monitors the user’s computer activity, often with the goal of stealing passwords or other sensitive information. Ransomware encrypts a user’s files, rendering them unavailable until a ransom is paid.
Users can help protect themselves from malware by keeping their computer software up to date. Software updates regularly include patches to fix security flaws exploited by malware. Commercially available antivirus software can also help prevent, detect, and remove some types of malware. Many networks use a security system called a firewall to defend against invasion by malware.
Personal computers may be particularly vulnerable to malware when users surf the World Wide Web , download or install programs off the internet, and open email attachments. Users should avoid opening suspicious or mysterious emails and email attachments, including emails from unknown senders. They should also avoid downloading and installing software from untrustworthy or unverified sources.
