CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

3.1. My Computer Has a Virus!

A virus is a piece of software designed to do harm to the system in one fashion or another. The virus is typically associated with a file; and when that file is opened, the virus is activated and does its damage to the system. The damage could be disastrous in the sense that the system no longer starts up, or it might just create a faulty system that is annoying to work with. Either way, the virus has done its job — to cause pain and suffering in your computer's life, and yours!

3.1.1. Types of viruses

A number of different types of viruses can infect your system:

• Boot sector: A boot sector virus attacks the boot code contained in the boot sector of the disk. This type of virus loads every time the system boots up and sometimes may even prevent the system from booting.

• File: A file virus attaches itself to an executable file and is run, or activated, when the executable file is run. This has been one of the most popular forms of viruses for many years because the attacker simply has to trick you into running the executable.

• Macro: A very popular type of virus today is the macro virus. A few years ago, Microsoft was promoting the fact that you could program your own macros to customize Microsoft Office applications (such as Word, Excel, and Access). A macro is a set of Visual Basic for Applications (VBA) commands that performs a specific task. VBA can also be used to call other programs. For example, I created a macro in Excel that automatically starts ...