Malware is a term used to describe any intentionally malicious software. Malware includes computer viruses, worms, trojan horses, spyware, and other unwanted software. If you agree to ads to get a program for free, or a website pops up an ad or two, it is not considered malware. Defective software which has unintentionally harmful bugs is not considered malware. Viruses and worms are forms of malware that replicate themselves. Trojans are usually e-mail attachments which run when an unsuspecting user clicks on them. Any of these can install a payload or root kit, a package of additional software which lets someone take control of your computer, in order to use it for other devious purposes. Infected “zombie computers” are used to send email spam, or linked together in “bot-nets” to engage in distributed denial-of-service attacks. Dialers are programs that use your modem, they can run up charges on 1-900 numbers. Spyware can track your web browsing and may include key loggers which record what you type, including passwords to bank accounts and other personal information. Other malware will force you to use a specific page as you home page, or direct you to a specific search engine.
Malware has a variety of symptoms. Slowness is one symptom, but slowness can be caused by many things, so don’t panic over slow web browsing. But if your computer is suddenly much slower after you clicked on a strange message box, then you probably were tricked into downloading some malware. If your computer is locked to a home page you do not want, or if you are using a firewall and it often warns you about a program trying to connect to the Internet, then you are probably infected. It is also possible to be infected without noticing anything, if the malware is designed to remain hidden.
Some things uses can do to avoid being infected are:
1) Remember e-mail is not always from who it appears to be from. So don’t click on attachments, give out your password, or delete files from your computer based on e-mail warnings.
2) Set your browser to higher security settings. In Internet Explorer, find them by clicking Tools, then Internet Options. In Firefox, click Tools, Options. There is a box with Content, Privacy, and Security tabs in both browsers.
3) Be careful what you download. Most malware needs to be manually installed, so it is included with other software. Avoid clicking on unexpected e-mail attachments and any boxes that pop up offering to fix a problem, they are more likely to cause one. Also beware of using USB drives you find.
If you suspect your computer is infected by malware and you are using Windows, Microsoft has a malware removal tool. You can run also run a check at Trend Micro.