Malicious software, commonly referred to as "malware" is a term that refers to any software designed to gain access to and use without the owner's knowledge, or cause damage to a computer or a computer network. The various types of malware include adware, spyware, viruses, and rootkits.
Adware is software that displays annoying popup ads and advertising banners. Adware is frequently is bundled with free software that a user might feel is useful. The user doesn't completely read the EULA (End User License Agreement) when installing the free software, so they inadvertently agree to installing adware. While adware usually doesn't cause permanent damage to a system, it can be annoying and can degrade the performance.
Spyware is software that monitors a users action while using a computer. when the computer is online the spyware sends the information it gathers to the hackers that created it. Sometimes the hackers sell this information for use by marketers. Some types of spayware log keystrokes in order to capture usernames, passwords, and credit card numbers which they either use for theft themselves, or sell online for other hackers to use.
Again, spyware can be bundled with free software, and when the user doesn't completely read the EULA when installing the free software, they inadvertently agree to install the spayware. While spyware may not cause permanent damage to a system, it can cause damage to a persons finances and credit when used for identity theft.
A Virus is a program who's main purpose, similar to a biological virus, is to make copies of itself and to spread those copies to other systems. Sometimes a virus is not intentionally designed to cause damage, but as it spreads itself across the network it can cause serious performance problems. Other viruses are designed to move or delete data from a system. Some viruses are designed to cause damage by modifying or deleting operating system files.
A Worm is a type of virus that, unlike a usual virus which requires human interaction to spread from system to system, has the ability to replicate itself and spread from system to system on it's own without human interaction. One common method for a worm to replicate and spread is to access an e-mail address book on the system and to send itself to everyone on the list, accessing the address books on those systems and sending itself to everyone on those lists, and so on. As the worm sends hundreds of thousands of copies of itself, it can cause performance problems over the entire Internet.
About 1200 B.C. after a fruitless 10-year siege on the city of Troy, the Greeks constructed a huge wooden horse, and hid a few soldiers inside. They then left, leaving the horse behind. The Trojans, seeing that the Greeks had left, pulled the horse into the city. That night the soldiers crept out of the horse and opened the gates for the rest of the Greek army who entered and destroyed the city.
A Trojan Horse is type of virus that presents itself as a piece of useful legitimate software, but much like the Greeks wooden horse, when installed and executed, it actually does damage to the computer. Unlike a regular virus, a Trojan Horse (sometimes referred to as just a "trojan"), does not replicate itself. Like a regular virus a Trojan Horse can move or delete data, or cause damage by modifying or deleting operating system files.
Ransomware is malware that is downloaded to your computer. The ransomware encrypts files on your computer, including critcal business files or your precious family photos and videos. Encryption involves using a huge randomly generated number, called a key, to encode the binary data of which a file is made. You can't restore the file without the key. And since the key is such a huge random number, nobody, except the ransomware criminals and maybe the National Security Agency, has the ability to recreate the key and decrypt your files.
You'll receive an email or a window pops up informing you that if you fail to pay a ransom of from several hundred to several hundred thousands of dollars, the key to decrypt your files will be destroyed. In order to pay the ransom you'll need to convert your money to Bitcoin, an untraceable virtual currency. After you convert your money and pay the ransom, the cyber criminals may, or may no, send the instruction to restore your files.
The best way to protect yourself from ransomware is to backup your imprtant files frequently. If you are the victim of a ransomware attack, Take your computer to a qualified computer service shop like the Best Buy Geek Squad where they should wipe your hard drive clean and reinstall the operating system.
A Rootkit is actually a malicious modification to an operating system file or files. The rootkit gains administrator rights to the system, and then uses those rights to keep it's files hidden and its process from being visible in the system's list of processes. Rootkits are commonly used to turn systems into "bots" to join a "botnet" where they can be used to send out spam e-mail, or carry out a DOS (Denial of Service) attack against a website causing it to crash.
Grayware is a term used for any type of malware that is annoying and may consume system or network resources, but does not actually damage the system or network. Adware is a type of grayware. Spyware is a type of grayware, that includes monitoring programs such as keyloggers that do not damage the system, but they do introduce a security risk.
Because many grayware programs are installed by users along with another program that were agreed to by accepting the EULA, antivirus program makers who detect and automatically remove the grayware can sued for causing damage to the grayware maker's business. For this reason some antivirus programs now just flag grayware as "potentially unwanted programs" and let the user choose to remove it.
The best way to avoid malware is use ant-ivirus, anti-spyware, and anti-adware programs, and to keep them updated. Some programs claiming to be anti-malware applications are actaully malware themselves, so install only anti-malware programs that are well known and, because malware often uses the same name as legitimate software, download only from a reputable source. That also applies to any application that may claim to be useful legitimate software. Research any application on google before installing.
Backup all your files to an external drive. This may be a CD,DVD burner, or a removable hard hard drive. You should back up at least monthly, and depending upon how rapidly you create files, maybe weekly or daily. Keep at least two backup versions, the latest one, and a previous one in case your current backup actually backs up the malicious program along with your files.
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