StopBadware's Top 50 lists are based on the number of URLs currently blacklisted by our data providers: Google, ThreatTrack Security, and NSFOCUS.

Important notes about the data:

• Blacklisted URLs may be compromised (i.e., legitimate sites that have been attacked) or malicious.
• URLs may be blacklisted for any of the following reasons:
  • hosting badware files
  • redirecting to other badware URLs
  • displaying malicious ads
  • otherwise facilitating the distribution or operation of badware
• Many URLs remain blacklisted for a period of time after the URL is cleaned or disabled.
• The total number of websites or URLs hosted by an IP or AS is not reflected in this data.
• The data reflects the methodologies used by each data provider (e.g., Google aggressively scans its own properties, and NSFOCUS focuses on Asian hosts).

Because of the above points, the data should not be used to draw conclusions about the security practices of the service providers associated with specific IP addresses or ASes.