The extension you installed on your browser could be injecting ads into your favorite websites — even the ones that never feature advertising at all. This discovery led to a blog post by Philippe Beaudette of Wikipedia explaining that any appearance of advertisements on the site may be the result of ad-injecting malware installed on your system.

So how do you know if you’ve been infected with malware? Well, sometimes it’s as simple as checking the extensions installed on your browser. Other times, finding and removing malware on your system could be a lot like pulling teeth. You have to know exactly where to look for it, and how to pull it without causing damage to other important components of your system.

What is Malware and How Did It Get There?

Malware is short for malicious software, a broad term that covers a wide range of software that either disrupts or alters how your software functions, monitors and reports on your activity, opens a back door for would-be intruders to access your data through, or any number of other unwanted side effects. In many cases, malware presents itself as a useful program or browser extension that addresses a common fear or urgency on the part of the user to install it. For example, a virus scanning program that detects viruses on your computer remotely by way of a web page, almost as if by magic. To an unsuspecting user, the fear of having an infected system can drive them to actually install the malicious software itself.

Some other malware disguises itself as a requirement to access online information. Let’s say you’re a bored fellow browsing the Web during the night. You come across a link that promises to give you immediate free access to your favorite celebrity’s sex tape. You click the link only to be told that you have to install an extension to access the material. Once the extension is installed, you may or may not actually see what it is you came there for, so you move on feeling disappointed. All the while, malware is left on your system and the user is normally oblivious to that fact.

Email is another way that malware can make its way into your system. Predominantly associated with viruses, email-transmitted malware can actually reproduce and distribute itself once it has control of your system. This is why so many people get stuck with infected computers after opening an attachment sent by someone in their address book. It most likely isn’t entirely the fault of that person, they were simply the victim of malicious software.

How Do I Get Rid of It?

In Wikipedia’s case, many of the cases where advertisements appear on the page can be easily solved by uninstalling a malware extension on their browser. According to the blog post, the largest present offender is an extension called “I want this” and installs itself in Google Chrome. You can remove this type of malware by doing the following:

  • Open the Customize and Control Google Chrome menu via the wrench icon in the upper-right corner.
  • Go to Tools > Extensions.
  • Remove “I Want This” and any other extensions that you do not recognize or need.

As for the hundreds of other forms of malware out there, the solution may not be as simple as removing a browser extension. Some malware embeds itself deep in your system and hides in such a way that antivirus programs don’t easily detect it. If a virus attaches itself to an important system file, you might as well format and reinstall to avoid the threat of breaking your computer and/or suffering from reinfection.

If you feel that you may have installed malware on your system, the best first step to removing it is to get out of your normal Windows operating environment and into safe mode. You can do this by rebooting your computer and hitting F8 over and over again until you get a screen that gives you the option to boot into Safe mode.

Once there, things will look a little different, but it’s really just an operating environment within Windows that disables all the potential threats to your system and operates off of only your core resources. Here, you can safely carry out the removal of any malicious software that may exist.

Two good programs to try in this case are Malwarebytes Anti-Malware Free and Kaspersky Virus Removal Tool 2011. These programs will help you scan for and remove potentially malicious software. You can speed this process up by running Disk Cleanup or manually deleting files in your temporary cache folders. These files can usually be removed without impacting anything critical and may be potential hiding spots for malware.

You’re also going to want to make sure your browser isn’t impacted by the infection. Check your extensions, connection settings, and home page to make sure that your browser isn’t being thwarted by malware.

If your scans with the malware removal tools came up with anything, make note of the names of the malware and use another system to research methods of removal. Kaparsky has a great knowledgebase filled with useful removal tips for everything from basic extension malware to trojans and more tricky viruses.

Once you’ve done all this, you can reboot into regular Windows mode. At this point, you’ll want to check your system out to make sure everything is back the way it was before the signs of infection became apparent. You may be in the clear.

Know When to Format and Reinstall

Not every malicious software out there requires a format and reinstallation of Windows to recover from. Still, if you know your computer is infected, it’s probably best to move any documents, images, and/or video files to a flash drive or other external storage medium before formatting your system. Simply reinstalling Windows over itself doesn’t get rid of the virus every time. It might also be argued that hidden partitions with restore data on it may also be subject to infection, so remember to burn restore discs as soon as you get your new computer. This may not help you if you’re reading this, but it’s a great tip for the future.

Formatting and reinstalling Windows is the best way to nuke anything that may be corrupting your operating environment. It’s a pain in the keester, but it sure beats whoever is on the other side of that virus getting access to your logins, banking information, or search history.

Again, this isn’t required in all cases, but it is the best way to get rid of everything and anything that may be threatening your system.

What about you? How do you deal with malware? Have you seen ads appear on Wikipedia?

Image By: Kizar on Wikipedia