About computer viruses
First computer viruses appeared in 1960s or 1970s. Computer virus programms became a real threat in 1980s then Apple computers became popular. Viruses were able to run themselves and make harm to user’s computer. First Anti-Virus utilities were created in 1984. They were able to block processes launched by computer viruses. At that time computer viruses used to spread via external storages and devices.
Now when we can't imagine our life without online, computer viruses mostly injure our computers via internet. You probably have already heard about viruses, trojans, worms, spyware, fishing and others. Let's see what threats exist and how they may harm your computer.
Fishing
Fishing is not a malware in general. It means that hacker makes website which looks like your email service or a site of your bank, send you a link to this site and collects your login, password and credit card number. In fishing the main channel to send link to hacker’s website is user’s email. Other branches of fishing are Farming and Typosquatting. Farming attack is possible when user’s PC is infected by malware which redirects user from their bank’s website to hacker’s website. Typosquatting works when hacker makes website with URL which is very similar to original website URL with a little typo, for example yahjoo.com. The main harm of all types of fishing is stealing user’s confidential information. Hackers website may also infect user’s computer or mobile phone with malware.
Viruses
In last ten years the word ‘Virus’ became a general term for all malware. From a technical point of view virus is a malware which makes a copy of itself to other programs and code. A lot of viruses penetrate to computer via attachments in emails, chats, social networks etc.
Worms
Worm is a kind of self-replacing malware. Worms use vulnerabilities in operating system, browser and firewall. Worms scan all network and find other vulnerable computers. This kind of malware can send itself via your post client or skype to all your contact list.
Spyware
This malware collect user’s information and sends it to hackers servers. The number of spyware is growing from year to year. Spyware may collect keyloggers, URL loggers, screen recorders, software that replaces web requests. In most cases hackers use several types of these software. Some kinds of spyware replace content in user’s browser and show ads - they are relatively safe. Other spyware collects all information how user interacts with computer or mobile phone, including bank accounts, personal data, passwords and even photos.
Trojans
Its another one type of malware which is disguised as harmless programs and infects user’s computer. One of the ‘favourite’ way of spreading trojans is silent installs with other software, such as video codecs or pdf viewers. The point is trojans never contain maleficent code when they are installed, they download it after. Trojans also do not copy themselve as viruses or worms, they require user action instead. Trojans are more difficult to recognize and users even don’t know that their computer is infected. A lot of botnets are organized with computers infected by trojans.
Rootkits
Rootkits are extremely dangerous software which can get the higher (administrator) level access to user’s computer or mobile phone. After that user may not be able to uninstall or install programs or even to login into operating system. In most cases rootkits go with viruses and trojans and they require users action such as open file. The main problem is that it is very hard to remove rootking using an infected operating system. External hard drives with own operating system may solve this problem. In last 5 years the number of rootkits for mobile devices encreased.