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Computer Viruses, Worms and Trojan Horses Know the Difference

Malware is short for “malicious software,” and refers to software programs designed to damage or do other unwanted actions on a computer system. Common examples of malware include viruses, worms, Trojan Horses, and spyware.

We have all heard the above terms and probably use them interchangeably. But do we really know the difference? The following are some basic definitions:

Virus: Self-replicating malware that attaches to executable files. The infected program has to be run for the virus to spread. Typically viruses will seek out system programs that will start when the system starts. Or they will seek out specific software that is ubiquitous across the platform on which the virus is designed to attack.

All anti-virus software is reactive. In other words, for all of these, the anti-virus software has to already “know” about the specific malware to be able to prevent it. In the event of web site pop-up malware, most, if not all, anti-virus software will happily let one install the software that is masquerading as anti-virus software. In some cases, the end-user might get a warning that the software is malicious. But often, no warning is given, even with web scanning enabled in the anti-virus software. Then the unknowing user clicks on the dialog box and essentially, but unknowingly, agrees to infect the system.

Worm: Self-spreading malware that attacks un-patched, vulnerable “services” on networks. These usually are a “rootkit” (defined as software that enables continued privileged access to a computer while actively hiding its presence from administrators) running on an infected system that will attack print servers, name servers, web servers, file servers, and the like. All modern desktop operating systems are likely to be running a service of some sort. Server systems will definitely be running some services. These malware only succeed if the service is vulnerable due to not being patched or up to date. A successful attack will then install itself as a new “rootkit” on the infected system and start scanning a network for more vulnerable systems it can successfully attack from the newly infected system.

Trojan Horse: Embedded malware that requires the end-user to install an application that is pretending to be something it is not. This is the most prevalent attack these days. In some cases it preys on a user’s ignorance by using social engineering (the art of manipulating people) to get the user to install malware. Fake anti-virus pop-up messages from infected web sites are the most common infection vector. In other cases deliberately infected source install files from “strange” web sites is the other attack vector. A Trojan Horse may include a virus, a worm, or both.

In order to protect your network applications and data, anti-virus and fire-wall software need to be used together. Unfortunately, however, even doing both is not a guarantee that you won’t become a victim. I refer again to the statement made earlier in this article: All anti-virus software is reactive. For all of these, the anti-virus software has to already “know” about the specific malware to be able to prevent it.

Using one or the other gives you some protection. It is better than nothing at all. But if you want to sleep at night and know that you are protected as best as is available, you need both. Perhaps this example may help. Think of the flu shot that you get. It does not guarantee that you won’t get the flu but it protects you from getting the known flu ‘bugs’ that are out there at the current time.

There are better ways to handle this type of attack. With Wilson Technology Group, we can proactively reduce the possibility of this happening at all. Call 352-796-9891 today!

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Wilson Technology Group, Inc.
24332 Dorsey Smith Rd.
Brooksville, FL 34601 USA
Phone: 352-796-9891
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We provide sales and repair of computers, networks, phones, and security cameras in Citrus, Hernando, Hillsborough, Lake, Levy, Marion, Pasco, Pinnelas, Polk, and Sumter Counties