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Malware - Viruses, Worms, Trojan Horses, Spyware, Bots, Rootkits

Home computing has become ubiquitous in our society. Once the domain of “nerds,” the technology has advanced to provide a much more user-friendly machine that can be a source of entertainment for the whole family. However, many people connect their computer to the Internet, turn the machine on, and go on their merry way without giving a thought to the dangers lurking in cyberspace.


Malware is the term that describes any software placed onto a computer without the owner’s (or user’s) knowledge or permission. Malware can be as simple as a prank that places a line of text inside some of the computer’s coding, to intrusive programs that cause damage to millions of computers around the world, the work of professional cybercriminals.


For the most part, malware is placed onto computers through vulnerabilities. Vulnerabilities are weak points or errors in operating system or application software that allow cybercriminals gain access into the machine. The most common mode of travel for malware is through open broadband Internet connections.

The growth of broadband Internet access has made computers much more vulnerable to malware attacks. When dial-up Internet access was the only way to connect, most people would only be online for a few minutes at a time, and then would disconnect their computer from the Internet for a long period of time by simply “hanging up.” Now, with broadband Internet access, computers are always connected, giving cybercriminals access even when a computer isn’t on.


The different types of malware can be broken down into several categories. Some types of malware need the target to actively accept the malware and execute it. Other types are active attacks that come from cybercriminals who are scanning network for vulnerabilities. Some malware attacks are passive, with hackers lying in wait on Web sites.


Here is an overview of several of the different types of malware:

Infectious malware

Infectious malware is usually more of an annoyance than an attack that can cause identity theft or a profitable outcome. However, they can be the first attack that can open the door for more vicious attacks because it lets other cybercriminals know that the computer has a vulnerability. They can also do a severe amount of damage, so much so that the computer won’t work anymore.

  • Viruses are the most commonly known type malware. Many people mistakenly give the label “virus” to all types of malware, but a virus is a form of malware. Viruses are self-replicating programs that need the target to execute the program in order for it to work. Viruses are often how cybercriminals get started, many times as a prank or trying to show off their knowledge. However, professional cybercriminals can cause widespread damage to numerous computers, costing millions in damage.
  • Worms, on the other hand, are attacks on networks rather than on computers. Their main intent is to slow down or disrupt network activity. However, they can also carry payloads of malware, such as viruses, and drop them onto unprotected computers.

Web threats

While infectious software looks to break through vulnerabilities in operating system software, Web threat malware looks to break through vulnerabilities in applications, such as Web browsers and instant messaging programs. These are generally programs that look to steal information from the target or to make profit for the cybercriminal.

  • Keyloggers record form data entry (such as passwords and credit card numbers) and report back to cybercriminals
  • Spyware are programs that look to steal information, whether its taking data from the files that are on the computer or that track the target’s usage.
  • Adware are programs that allow content-based pop-ups or diverting search engine results to advertising.
  • A bot is a malware that allows a cybercriminal to run a computer remotely. Multiple computers infected by the same hacker (known as a bot herder) are known as a botnet. Hackers do this for bragging rights, or to provide remote locations for illegal activities. Botnets can number in the thousands and millions.
  • Dialers target dial-up modems, forcing them to dial premium phone numbers (1-900 numbers) and racks up charges for the owner. These are becoming rare as dial-up modems are falling out of favor.

Concealment malware

As the name implies, concealment malware are malicious attacks that try to hide illegal activity in one form or another.

  • Trojan horse is malware that appears to be something beneficial or desired by the user, but hides a malicious program. One type of a Trojan horse is spyware that is embedded in a game, and reports computer usage back to the software manufacturer. Although this isn’t dangerous per se, it’s still intrusive and usually unwelcomed by the user.
  • Fake antivirus software tricks the user into thinking it’s a useful program, when in fact the software either is ineffective or completely bogus, or masks malware itself. It can hide itself by disabling real antivirus software.
  • Backdoors are malware that helps a cybercriminal bypass normal security features. Once a backdoor is installed, more can be implemented to help make the task easier for other attacks.
  • Rootkits are programs that can mask illegal activity. Rootkit can prevent other malware from being detected, or even open the door to bot herders.

In general, there are a couple of ways of combating malware. Having high quality, subscription based software such as Norton 360 can protect against all of these different types of malware threats. Making sure all software, including application and operating system, is up to date with the latest patches can close vulnerabilities. Also, making sure all users of a computer are aware of how threats can travel onto a computer, such as through attachments in e-mails, can help prevent malware attacks.



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