Malwares

Malware (a portmanteau for malicious software) is any software intentionally designed to cause damage to a computer, server, client, or computer network (by contrast, software that causes unintentional harm due to some deficiency is typically described as a software bug). A wide variety of malware types exist, including computer viruses, worms, Trojan horses, ransomware, spyware, adware, rogue software, wiper, and scareware.

Programs are also considered malware if they secretly act against the interests of the computer user. For example, at one point Sony music Compact discs silently installed a rootkit on purchasers' computers with the intention of preventing illicit copying, but which also reported on users' listening habits, and unintentionally created extra security vulnerabilities.

A range of antivirus software, firewalls, and other strategies are used to help protect against the introduction of malware, to help detect it if it is already present, and to recover from malware-associated malicious activity and attacks.

How malware gets installed

There are a lot of ways malware can get onto someone's computer. One common way is through email attachments. These attachments are usually sent from other computers that already have malware on them. When someone downloads and opens the attachment, the virus installs and uses their computer to send itself to even more people.

Another way malware installs itself is when a victim gets malware just by going to a website with the malware hidden on it. This is called drive-by downloading. A user does not have to click anything for their computer to get infected from a drive-by download. This kind of malware attack is usually found on websites that are not used a lot or whose security methods are very old. However, even current websites that people use all the time can host drive-by downloads when someone hacks the site.

People who write malware also get their programs onto computers by attaching them to real programs that people want. This is most common with pirated programs. This is because the downloader was doing something illegal and cannot complain to the authorities without getting in trouble themselves. However, some non-piracy websites also put malware (or other unwanted programs that are almost as bad as malware) in a download with real, legal software in a process known as bundling. Computer security experts complain about websites that bundle real software with malware. Their complaints do not always stop the websites from bundling.

Kinds of malware

There are many different kinds of malware. Each acts a different way.

• Viruses are a kind of malware that needs a user-run program to work. They cannot copy themselves or move from one computer to another without a program to host it. Viruses are very common in pirated programs. They can harm computers in many different ways, like deleting files and stealing passwords.

• Worms are a lot like viruses and can cause the same kinds of damage. However, they're able to move through the internet and copy themselves onto computers without help from a host program. This makes them more dangerous than a virus. Worms are usually found in emails and drive-by downloads.

• Trojan horses are a type of harmful software that masquerades as a regular, benign program or utility in order to persuade a victim to install it. A Trojan horse usually carries a hidden destructive function that is activated when the application is started. They need a user to agree to run a program to work and cannot copy themselves from one computer to another. However, trojan horses can make the same problems a normal virus can make. They can also allow the malware writer to control the victim's computer, install more malware, steal bank data, and more. For example, ransomware is a type of trojan horse that stops a victim from using their files until they pay the person who wrote the malware. Experts think that trojan horses are the most common type of malware in existence.

• Adware is a type of malware that earns the program authors money with advertising. These programs show users ads and force them to use websites that make money for the malware writers. An adware will also find personal information about the victim (such as their age, race, and job). This is so the malware authors can sell the information to other people. A user can usually uninstall adware easier than most malware. However, this is still difficult to do without a specially-designed program.

• Spyware is a more dangerous kind of adware that steals more information from a user. Spyware can steal someone's Internet traffic, account passwords, and anything they have typed into their computers. Spyware is also much harder to uninstall than adware is.