What is malware?
Malware is short for “malicious software.” Malware is any kind of unwanted software that is installed without your adequate consent. Viruses, worms, and Trojan horses are examples of malicious software that are often grouped together and referred to as malware.
Types of malware
Some categories of malware are:
- Virus – Software that can replicate itself and spread to other computers or 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. Types of information that is gathered includes the Websites visited, browser and system information, and your computer IP address.
- Browser hijacking software – Advertising software that modifies your browser settings (e.g., default home page, search bars, toolbars), 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. For example, an instant messenger software bundled with a program such as WildTangent, a known spyware offender. Peer-to-peer file sharing software, such as Kaaza, LimeWire, and eMule, bundle various types of malware that are categorized as spyware or adware. Software that promises to speed up the Internet connection or assist with downloads (e.g., My Web Search) will often contain adware. Another common way to infect a computer through email containing a seemingly benign link or email 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.
The Microsoft Malicious Software Removal Tool is an anti-malware utility that checks computers running Windows 8, Windows 7, Windows Vista, Windows XP*, Windows 2000, Windows Server 2012, Windows Server 2008, and Windows Server 2003 for infections by specific, prevalent malicious software—including Blaster, Sasser, and Mydoom—and helps remove malware and any other infections found.
When the detection and malware removal process is complete, the tool displays a report describing the outcome, including which, if any, malware was detected and removed.
*The Malicious Software Removal Tool will continue to be provided for Windows XP through July 14, 2015; it will also continue to be delivered automatically via Windows Update and for download via the Download Center.