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What is malware?

"Malware" is a term for any software that gets installed on your machine and performs unwanted tasks, often for some third party's benefit. Malware programs can range from being simple annoyances (pop-up advertising) to causing serious computer invasion and damage (e.g., stealing passwords and data or infecting other machines on the network). Additionally, some malware programs are designed to transmit information about your web browsing habits to advertisers or other third party interests without you knowing.

To protect all computers from unwanted attacks, IS&T provides Sophos anti-virus software free of charge to the MIT community. Sophos can be installed on Windows, Linux, and Mac computers.

Types of malware

Some categories of malware are:

  • Virus: Software that can replicate itself and spread to other computers or that are programmed to damage a computer by deleting files, reformatting the hard disk, or using up computer memory.
  • Adware: Software that is financially supported (or financially supports another program) by displaying ads when you're connected to the internet.
  • Spyware: Software that surreptitiously gathers information and transmits it to interested parties. Information gathered includes visited websites, browser/system information, and your computer's IP address.
  • Browser hijacking software: Advertising software that modifies your browser settings, creates desktop shortcuts, and displays intermittent advertising pop-ups. Once a browser is hijacked, the software may also redirect links to other sites that advertise, or sites that collect web usage information.

How malware gets through

Malware writers are very experienced in using tricks to get users to download their malware. Software that comes bundled with other software is often called a "Trojan Horse." Peer-to-peer file sharing software bundles various types of malware that are categorized as spyware or adware. Software that promises to speed up your internet connection or assist with downloads will often contain adware. Another common way to infect a computer is through email containing a seemingly benign link or attachment.

Malware can exploit security holes in your browser as a way of invading your machine. Sometimes websites state that software is needed to view the site, in an attempt to trick users into clicking "Yes," thus installing software onto their machines. Another trick is if you click "No," many error windows display. Other sites will tell you that using a certificate makes their site "safe" which is not the case. Certificate verification means only that the company that wrote the software is the same as the company whose name appears on the download prompt.

Some malware provides no uninstall option, and installs code in unexpected and hidden places (e.g., the Windows registry) or modifies the operating system, thus making it more difficult to remove.