Low

• Used to deliver targeted advertising.Shows non-intrusive (occasional) ads of an inoffensive nature.
• Cookies

Mild

• Tracks non-identifiable personal information (browsing and search information.)
• Installs other potentially harmful components without user consent.
• Adds URLs to the user's Favorites menu and desktop.
• Peer-to-Peer applications (typically, music, unofficial celebrity Web sites, adult sites, and games) that can install Spyware.

Moderate

• Uses intentionally misleading tactics to trick the user into installing some software. 
• Aggressively displays advertisements (frequency of display impedes computer usage and performance.) 
• Premium rate dialers (Can initiate expensive 900 calls automatically.)

High

• Installs without user consent. 
• Hijacks search pages or homepages. 
• Displays frequent unwanted potentially offensive Pop-up ads. 
• Adds URLs to the user's Favorites menu and desktop, that direct the user to pornographic or other potentially offensive Web sites. 
• Infects a computer's hosts file and/or modifies the TCP/IP settings to send the user to a different Web site.

Critical

• Transmits sensitive data to third parties without user consent (banking info, passwords, Windows product ID and CD keys.) 
• Provides no uninstall (removal) capability. 
• Defends itself from being uninstalled (removed.) 
• Hijacks desktop or homepage. 
• Disables anti-virus and firewall applications. 
• Prevents anti-virus programs from receiving updates. 
• Reduces system security. 
• Allows access to remote users. 
• Spreads to other computers on the local network. 
• Downloads and installs other Spyware applications. 
• Sends spam. 
• Performs a denial of service attack.