Hacking viruses are computer programs which can steal personal information and control a system remotely. They typically spread through emails or peer-to-peer networks, as well as websites with content that is downloaded. You can avoid a hacking attack by ensuring you update your software, staying away from downloading unreliable sources, and staying away from vulnerable networks.
Cybercriminals use hacking viruses for all sorts of reasons. They may want infect computers with keystroke logs that track all the words a device user types. This provides the perpetrator with all the information needed to steal an identity and gain access to bank accounts, credit cards and other valuable information. They could also use a compromised system as part of a network known as a botnet which can be used to send out spam emails or launch attacks on other devices.
A virus may be crafted to overtake the functions of a computer by changing its start page or redirecting search queries to an undesired web site or reversing the results generated by popular search engines. This kind of hacking could be referred to as a backdoor.
Hackers who were interested in finding low-tech ways to bypass secure telecommunications and expensive long distance calls were historically called Phreaks. Phreak is a combination of the words phone and freak. The majority of people who fall victim to viruses that hack computers today do not have anything to do with telecommunications, nor with tinkering around with technology. They are the unfortunate victims of malicious hackers who exploit vulnerabilities in built-in security systems on computers to steal sensitive data, disrupt normal computer use and cause financial damage to their target.