Viruses, trojans, worms ... what ghosts might be lurking in your machine?

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Can a computer virus really steal your data? Yes, and worse. 

Some cyber-attacks can result in your computer being made into a "slave" to a remote user out on the internet. Malware can hijack your system in many ways: it can keep watch quietly until it gets a signal from the "master" to do something ... it can immediately start doing something ... it can turn your computer into a doorstop. 

A computer virus is software that copies itself onto your computer and then makes copies of itself. Viruses can be harmful or not. A virus infects files on your computer. Many viruses are created by "script kiddies" who are just trying to see if they can make one, and rationalize their actions by saying it's your fault for not having antivirus software installed. 

A computer worm is a program that copies itself onto your computer but doesn't have to hide inside another file. It is a file. Once it's on your system, it reaches out through the internet from your computer to find and infect other unprotected computers. Many worms are propagated through email links. 

A trojan (from the Trojan Horse) is an evil virus that isn't there to  change  your files ... it isn't there to just copy itself around the web ... it's there to do something nasty to your computer. Could be almost anything. A trojan is a "back door" to your computer for someone out there on the internet to use it as they want. It could erase your hard drive ... or corrupt all your files ... or search for any file that looks like it contains passwords or personal information and send that to someone .. or download stuff ... or upload stuff ..  or send all your keystrokes off to someone ... or work with other infected computers to attack a website (denial of service attack) or send out spam.  

All together these bad things are called malware. Malware is any kind of program that intentionally does something it shouldn't be doing. You MUST protect yourself from malware. 

1. Enable the firewall in your operating system. Most operating systems like Windows have firewall functionality included, and you should enable it. All it does is restrict outside computers from connecting to yours. It's a good first line of defense. Just search for "firewall" in your computer's help files and you should get the instructions you need.

2. Enable the firewall on your wireless/wired router. It's buried somewhere in the admin panel. You can usually log in to your router at an IP address like or ... google "IP address myrouterbrand" to  find the manufacturer defaults. Default login is usually something like admin/admin. Find the firewall and enable it, if it isn't already on. Again, user manual or google for directions ...

3. While you are at it, you should really change the login information for your router to a userid and password that only you know (and write down/remember). Then, a passerby can't log in to  your router and enable themselves to use up your network data. 

4. While you're logged on to the router is a good time to check and see how many users are connected, and to disable the guest account, and to change the network password. This at least boots off any freeloaders who've been freeloading and keeps them from latching back on.

5. Now you must install and run some antivirus software. If your computer is already infected, the virus will be able to hide from the antivirus pretty well. Most antivirus programs instruct you to reboot the computer from a CD so that the antivirus program can load a clean operating system and check for these hidden viruses. Once it's satisfied that it has them, you can go ahead and install it, and set up regular screening and checking. Each antivirus program will have its own instructions that you should follow. 

6. For Windows, Kaspersky is the best of the antivirus programs, but it doesn't catch all malware. There's a program called Malwarebytes that is excellent. Ah, jeez, I really don't feel qualified to recommend one ... I used many of them, because sometimes one will catch something one misses. Don't have them running at the same time, though. Pick one to monitor your system and stick with it. 

7. Here's a link to a PC Magazine article on antivirus software for   2015:,2817,2372364,00.asp

8. For the Mac, you don't need to worry very much ... there are viruses written for the Mac, but as it's based on the very secure Unix operating system in practice it just doesn't happen. There are antivirus programs for Mac OS ... just not very many, because there isn't the same need. 

9. Keep your antivirus and OS software up to date. I know, it takes bandwidth. But let Kaspersky or whatever download updates whenever it wants to. Let Windows install the security updates every week (you can configure this for LNFZ). Let Chrome or Safari or Explorer or whatever browser you use update itself regularly. Attackers are always finding new ways to exploit vulnerabilities in operating systems, browsers, and applications and the good guys must constantly update their software to patch these holes. 

10. Finally, practice restraint. A piece of malware can come in a link in an email from someone you know, because some dang trojan hijacked their machine and sent it to you. A link can be placed, intentionally or nefariously, on a website that you sort of trust. A good rule of thumb is to be very careful about clicking links on websites that you aren't very familiar with, and to not click on any link in an email that just seems wrong. If you want to go to the site, copy the url from the link into your browser and go to it that way. Sometimes links   LOOK to you like they say one thing, but if you put it in the browser it says something else. Sneaky. 

Bandwidth loss is only one bad thing that can happen with any computer infection. If you notice your bandwidth use jump up suddenly, it wouldn't hurt to do a very thorough virus scan. If you haven't already installed an antivirus program on Windows, please do. There are some very good free programs that will give you some level of protection. If you do have an infection, data loss will be the least of your problems. Secure your system and your network first, and then start looking for data hogging applications. 

Now go out there and love teh interwebs!
Photo of Kentuckienne


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Posted 5 years ago

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Photo of Exede Kimberly

Exede Kimberly

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Woah great post Kentuckienne, lots of interesting info here! Keep it up.
Photo of HMC1940


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That is a excellent post Kentuckiene. Right on the money. Hope everyone reads it. I copied it and have it in a folder on my computer. :-)  
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Mary Brown

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In addition to Trojan horses and worms, adware, browser hijackers and other malicious programs have the ability to steal browser data and even users' sensitive information. See more information here.
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Diana, Viasat Employee

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Hi Mary, Thank you providing additional information about viruses,
trojans and other malicious programs. It was very helpful.
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Great description! I was once curious about Discovery App adware infection because of its malicious activities on my laptop including showing ads and degrading PC performance. I spent a few hours and figured it out.
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Tom Bird

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If you are using Windows 10 it will download (or push) updates to your computer in the background. Those updates can be rather large. I just got one that was 2GB. In addition to that I have observed that my modem downloads about 1kbyte/sec when nothing is going on. I am assuming this is just handshaking between my modem and the internet, as it continues even when my computer is off. I am certain no one else is accessing my router. If anyone else would be interested, try entering in your browser's URL box and clink on MODEM to watch your data usage. I would be interested if others observe the same thing.

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