When interpreting data such as our Top 50, please keep in mind that the URLs in our Clearinghouse are those provided to us by our data providers. Therefore, this data does NOT comprise a comprehensive report of all infected URLs on an AS or on an IP address; rather, it may reflect the methods employed by our data providers in detecting infections.
We map IP addresses to ASNs using data provided by Team Cymru. AS information is not available for all of the IP addresses in our database. Furthermore, since not all ASes are the same size, our Top 50 ASes list should not be interpreted as reflecting infection rates; it only describes the number of infections that are reported on each AS. It is therefore best to consider our infection prevalence data not in absolute terms, but relative to the size of other ASes, and over an extended period of time.
Certain other factors may influence the data we report, including the frequency with which StopBadware obtains data from various data providers and the success we have in resolving IP addresses for the URLs that are reported at a given time. Observable spikes in reported infections may occur if irregular batches of data are received from a data provider, and various events or attributes of our systems may also impact our results.
If your company is interested in providing data to be included in StopBadware's Clearinghouse, please contact us.