Using an internal tool, Barracuda analyzed Alexa’s list of the most popular websites to determine whether each URL was serving malicious content and doling out exploits to a browser or its extensions. Studies showed that on average, through the month, at least two of the top 25,000 sites served malicious content each day.
More statistics gathered by the researchers made it clear the malware analyzed was deeply rooted in the sites. In fact, in the URLs analyzed, exploits were distributed 23 of the 29 days of the month or 79 percent of the time, while over 97 percent of those malicious sites were at least one year old, showing the campaigns were making their home at more established sites.
Paul Royal, a Research Consultant at Barracuda, wrote a blog entry that helps boil down the mathematic equation used to tally each site’s number of views and infected users while the infographic below helps to better visually represent the month’s research.