Malware, or malicious software, is the scourge of the Internet. Malware can slow a computer to a crawl by running unauthorized background processes. It can consume bandwidth, leading to a sluggish Internet connection, and cause annoying popup advertisements or redirects of your browser. Malware might also bypass security measures, steal sensitive information, and trigger system instability. Luckily, there are various ways to remove malware.
Most computers have at least some anti-malware software already installed, such as an anti-virus (A/V) program. Try using the A/V's “on-demand” scanner to check your system. Be sure the program’s anti-virus database is updated before starting, and configure the software to not only detect but to remove malware. If the infection is a new strain, it might have slipped by the program prior to the virus signature being added to the database.
If you have a separate anti-spyware program installed, run its on-demand scanner next. If not, it’s a good time to download a program, install it, and allow it to do an in-depth scan of your system. Many malware programs are disguised as anti-spyware, so only use a program recommended and hosted by a well-established, reputable site such as PCWorld, MajorGeeks, ZDNet, TuCows, SourceForge, or the like.
As an adjunct to installed software, you can also use an online scanner hosted on a website. Caution is again warranted, as malware sites posing as anti-malware sites will return false results, scaring the surfer into installing an “anti-malware” program that is actually malware itself. Luckily, there are several, free reputable online scanners, which include the ESET Online Scanner, Trend Micro’s HouseCall, Panda’s ActiveScan, Computer Associates’ Threat Scanner, F-Secure’s Online Scanner, and more. Most free online scanners will only detect but not remove malware, though the ESET and Trend Micro online scanners do remove malware. An online scan requires ActiveX controls to be enabled and can take a considerable amount of time depending on the scanner and the amount of data to be scanned. In some cases it might be more convenient to let a scan run overnight.
Only one anti-virus program should be installed on a system at any given time, but several anti-spyware programs can be present, though having more than one running as a background process might slow the system or cause conflicts. When you suspect an infection, however, (or as a matter of monthly maintenance), you can open these programs, update their databases, and run the on-demand scanners consecutively to look for and remove malware. What one program misses, another might find. This is also the value in augmenting an installed A/V program with a periodic online A/V scan.
On occasions where you suspect or have confirmed that a specific infection is present, perhaps a virus or worm “making the rounds,” you might not want or need to scan the entire system, but wish only to address the particular threat. In this case, enter the same of the infection in any search engine, along with “+removal,” as in, virusname +removal. Follow reputable links to find potential fixes such as patches or small scripts that will check for and remove the malware.
If you receive monthly Microsoft system updates, the Malicious Software Removal Tool is automatically downloaded and run once to detect and remove malware, looking chiefly for timely, prevalent infections. When malware is detected and removed, the program generates a report to the user. This tool should not be relied upon as the sole strategy against malware, but does help to augment a monthly regimen of routine computer scanning that includes an up-to-date anti-virus program and at least one reputable anti-spyware program.
To prevent future infections, keep the operating system patched with the latest security releases, use a good A/V program that is updated daily, and compliment it with high-ranking anti-spyware. Avoid downloading software from unknown sites and beware of shared files such as torrents. Much malware is spread through email, so delete all mail that comes from unknown sources, unopened, and don't click on a file received through email unless it comes from a trusted source.