Malware is described as malicious software that can be invasive and nasty on business and home computers. They are usually in the form of worms, spyware, trojan horses (software that pretends to be useful) and net or web bots which hackers use to gain access to and control remote computers. With the explosion in internet usage and the availability of high bandwidth internet access tools like cable, DSL and T1, T3 etc., the writers of malware are also constantly evolving in the dispersal of their software. The recent trend is the localization of SPAM with the intention of making a message that could be flagged as junk email look like it came from your local chamber of commerce, the mayor's office or the youth soccer league, for example. These localized spam emails usually have catchy and very tempting headliners like "free t-shirts, tickets, baseball cap" if the unsuspecting user clicks on a link. Of course the link usually has an attachment that could be disguised as a PDF file where it is really an executable virus. Banner ads are also potential carriers of malware especially in social networking sites. We also see malware in software that offers to scan a computer for "security updates", "security threats" and "registry fixes" and "performance optimizers". Sometimes, malware is seasonal. So you may see a lot of IRS related malware during the tax season, or football related trojans during the football season. The recently concluded China Olympics saw a lot of maware offering all kinds of Olympic related "goodies". Malware writers have also been known to use variable data in their software whereby they personalize the attacks. In this case you may receive an email that promises John Doe season tickets to a local game from the local high school coach.

So how do you know if you have malware? There are certain tell-tale signs like a computer hard disk spinning loudly and the fan being more active than normal especially if the computer is idle. You may also experience long delays in opening and closing your applications where they used to open quickly. You may also experience a lag in your internet bandwidth especially if you have broadband. Another  thing to look out for especially in the case of botnets is if you suddenly start receiving NDRs or Non-Delivery Reports from strange mail servers that your email could not be delivered. In this case, your computer may be a zombie spam host.

What to do? Unfortunately for Microsoft Windows users, the best practice is to load up on security tools like Zone Alarm, AVG, Bitdefender etc. Some of these vendors offer free versions of their software which may be adequate for home users. There is also the need to download with caution. Just because a website offers to scan your computer for "free" does not mean you have to take their word for it. It is also a good practice to automate your security software as much as possible - automatic update of virus definition files, automatic scanning, scheduled scanning etc. For those who can afford it, the commercial versions of the various security software may be worth the investment because they include real-time scanning which means they are constantly monitoring your computer as you work. So if, for example, you downloaded a file that attempted to install a trojan, a good real-time scanner will detect the activity and prevent it. It will also do well to learn to refrain from clicking on any and everything that presents too-good-to-be-true offers like a free car. But the best option, in my opinion, is still to use a Linux based Operating System, not necessarily for the argument that Linux is better, but for the fact that a lot of the headaches we are discussing are just not there. If all else fails, visit the good folks at Tech Prognosis for free advice and some pointers.