Malicious software or malware is a software program that can cause your system to malfunction. Of course, a person will not knowingly download such a program. It is generally downloaded as an email attachment, or from a click on a pop-up window, or while browsing a malicious website. There are various threats posed to your system and hence it becomes very important to remove them.
What is a Malware?
It is nothing but a software, written by someone to access the information in your computer. When it is downloaded into the system, the user remains unaware of it. Its working totally depends on the motive of the program designer. A single software can encompass computer viruses, worms, trojan horses, spyware, etc.
Why is it a Problem?
Of all the threats that such a program imposes on the system, trojan is the most dangerous one. It works as a remote control of your computer. It can pass on private data like your account numbers and credit card numbers to the author of the malicious program. Hence, it causes a lot of damage. With a trojan running in your system, the programmer can even control the functionality and working of your computer. He can in fact manipulate the functioning of the other software and also control the working of the hardware.
If such a system is connected to a network, it can rupture the working of the operating systems in all the computers in that given network. Even if you disconnect your computer from an infected network or the Internet, it will decrease the performance of your computer. Even a single worm installed by the software can affect the performance. Various other functions like the 'Task Manager' and 'Folder Options' may stop working, limiting your control over the system. The malicious program in many cases behaves, as if it has lost its control and needs to download unwanted data into your computer, without your permission.
How to Remove it?
There are various tools and antivirus programs available in the market. However, we can also prevent such threats. For doing so, the operating system and other software that you have installed in your system should be original licensed copies. This allows you to update them. Avoid browsing suspicious websites. You can also use various software to stop pop-ups from appearing on your computer screen.
An accidental click on a pop-up may trigger the download of a malicious program. Before downloading any attachment that you have received on an email, verify the source or the person who has sent it. And most importantly, you need to install an antivirus software and set the firewall on.
There are various tools available for various operating systems. The Microsoft Windows Malicious Software Removal Tool allows you to clean up any malicious software from your system, if it has Windows XP, Windows Vista, Windows 2000, or Windows Server 2003 running in it. There are antispyware tools like the McAfee Anti Spyware that allows removal of such programs. MacScan is a similar software that has been designed for computers with Macintosh operating system.
There are various other freeware and open source tools which are available for free download. 'Spyboot - Search & Destroy' and 'Hijack This' are open source tools. It is very unlikely for Linux based systems to encounter any such problems. However, there are root kits available for Linux operating systems and some of them like the 'Root Kit Hunter' and 'FoundStone Carbonate' are available for Windows operating systems too.
A malicious program can remain idle in your system for a considerable period of time, depending on its functionality. There are various tools provided by different operating systems, which can help you in scanning your system for free to detect such programs.