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:: Where are the virus risks? |
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Viruses can reach your computer via all the routes shown below. You can read more details on the pages that follow. |
 Programs and Documents
Programs and documents can be infected with viruses. When you share them with other users, by putting them on your network or intranet, or by sending them out, the infection can spread. |
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The Internet
You may download programs or documents that are infected. Security vulnerabilities in your operating system can also allow viruses to infect your computer via the internet connection, without you having to do anything at all. |
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Email
Email can include infected attachments. If you double-click on an infected attachment, you risk infecting your machine. Some emails even include malicious scripts that run as soon as you preview the mail or read the body text. |
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CDs and Floppies
Floppy disks can have a virus in the boot sector. They can also hold infected programs or documents. CDs may also hold infected items. |
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:: Which Files Can Viruses Infect? |
Viruses can attach themselves to any code that runs on your computer: Programs, Documents, or the files that start up the operating system. |
Programs
Some viruses infect programs. When you start the infected program, the virus is launched first. This type of virus appeared early in virus history but still poses a threat, as the internet makes it easy to distribute programs. |
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Documents
Word processing or spreadsheet applications often use macros to automate tasks. Some viruses take the form of a macro that can spread from one document to another. If you open a document that contains the virus, it copies itself in to the applications start up files and infects other documents you open with that application. |
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Boot Sectors
When you switch on your computer, it accesses a part of the disk called the boot sector and runs a program that starts the operating system. The earliest viruses replaced this boot sector with their own, modified version. If the user started up their computer from an infected disk, the virus became active. |
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