Cybercrime is any action that uses a computer system or computer network as a weapon or an accessory in crime, or when a computer serves as the target of the act being committed.
Some of the most common forms of cybercrime include attempts to steal information by penetrating networks via malicious hacking, hijacking of online accounts and remote takeovers of computers to repurpose them for cybercrime.
Cybercrime can involve software that is invasive and hostile to the targeted computer or its user. Such malicious software is commonly called malware.
Network penetration is often carried out by groups of malicious hackers seeking access to protected files or databases in order to copy sensitive personal, corporate, financial or even political information.
Malware is often used to exploit flaws in a network's security system. For example, malware can be hidden in files attached to emails sent to users within a targeted organization. The end result is a data breach — the unauthorized copying of secured data.
Hijacking online accounts can be as simple as guessing a legitimate user's password or correctly answering password-reset questions. Hijacked webmail and social-networking accounts can be used for identity theft, to blackmail targeted users into cooperation, or to purchase goods and software and redirect the items' delivery to the hijackers.
Remote takeovers of computers enslave thousands of PCs into botnets without their legitimate users' knowledge. Such zombie computers, secretly controlled by cybercriminals, are used to pump out spam emails, place ads or malware on infected websites or even knock websites offline in distributed denial-of-service attacks.
Another popular variant of cybercrime includes fraudulent activities intended to steal money from the computer user.
These attempts may take the form of a phishing email message, such as the familiar Nigerian 419 or advance-fee scam, or more sophisticated banking Trojans, malware that infects Web browsers and hijacks online banking sessions, transferring money from victims' accounts to accounts controlled by criminals.
Computer users often unknowingly install malware on their machines. Some freeware programs deliberately conceal malware payloads, corrupted websites can infect visiting browsers, and many users unquestioningly open email attachments from trusted sources.
Crimes in which a computer user is targeted by another party are common, but many users also rely upon their computers to commit various crimes of their own.
The most prevalent such cybercrime by far is unauthorized file sharing. Its impact is debatable, but seemingly victimless crimes such as swapping songs via peer-to-peer networks or downloading free movies, television shows or software from unauthorized sites pose problems for the entertainment and software industries.
Other user-generated cybercrimes include cyberbullying and cyberstalking, which involve the harassment of targeted individuals through the Internet, often via social networks, and the viewing and distribution of child pornography.
Protecting a computer system from cybercrime
There is no magic solution to prevent becoming a target of a cybercrime, but there are several steps that can be taken to alleviate the risks.
First, experts recommend installing an anti-virus package on every computer that connects to the Internet. Anti-virus software can keep out malware and other threats.
Computer users also need to use common sense and develop an understanding of patterns often seen in scams online; this can help reduce the number of individuals who fall prey to criminals on the Internet.
By taking care to download only trusted files, run an updated operating system and use security software to keep out threats, users can greatly diminish their chances of becoming a victim of cybercrime.