They are designed for the following unpleasent intention: • Erase or overwrite. • Encrypt or Corrupt. • Upload or download the files. • Allow access to unauthorized user(s). • Spread other virus programs. • Tracking keystrokes of the user to capture Credit Card number or Passwords. 18.4.4 Rootkits Rootkits modify the operating system to hide them, and then use worm-like methods to propagate to other computers. 18.4.5 Spyware A Spyware sends information about the computer, your personal information or your Internet browsing activities to a third party. 18.4.6 Adware Adware displays unwanted advertisements. In general malicious software may: 1. Attempt to reproduce automatically and secretly. 2. Try to conceal itself from routine forms of detection (for example, using random file names) and elimination (for example, turning off your antivirus software). 3. Spreads itself to other computers via the network such as by e-mail, unsecured file shares, password guessing or exploiting security problems on other computers. 4. Modify the operating system or other legitimate software. 5. Make copies of itself to floppy disks, USB storage devices, CD-RW discs, or other writable media. 6. Send personal information gleaned from your computer back to the maker of the malicious software or his/her criminal associates, for purposes of identity theft or to collect market data. 7. Display unwanted advertising banners on web sites or in pop-up windows. 8. Allow malicious individuals to monitor your computer remotely over the network. 9. Delete damage or modify your documents and data files. In practice, you will often find a specific name like virus applied to a broad range of malicious software. The important thing to remember is that malicious software may combine any of the traits specified above. Malicious software is a serious threat to the secure operation of personal computers, particularly PC computers that use the Windows operating system.
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