Microsoft researchers have been looking into the problem of junk web pages, and have found that most of this 'search engine spam' comes from just two web hosting firms.
Microsoft's research, entitled Spam Double-Funnel: Connecting Web Spammers with Advertisers, looked primarily into redirection spam and reveals that the links to spam web pages are generated by a small number of people, with some major advertisers, hosting services and ad syndicators turning a blind eye.
The report found that the spam density of search results - i.e. the number of pages containing only advertising - was 11% on average, for the 1,000 keywords it studied.
For certain keywords, such as 'drugs' or 'ringtone', spam density was much higher, 30.8% and 27.5% respectively for the two terms.
The researchers found that an 'overwhelmingly large percentage' of spam-ads clickthrough traffic came from two IP blocks, meaning that just two web hosting firms are responsible for a large amount of spam listings.
The report refers to this as the 'bottleneck' of the spam double-funnel referred to in the report's title.
In addition, the report found that a small number of ad syndicators serve as middlemen connecting advertisers with the majority of spammers. The top three ad syndicators were involved in between 59% and 68% of the spam redirection chains sampled in the research.
These findings from the report provide the hope that the problem, unlike the more complex issue of email spam, could be solved or significantly reduced by taking action against a small number of operators.
The report also added that some well known websites' ads had 'significant presence' on spam pages, as well as making the point that it is advertisers' money which is funding the search spam industry.
The authors of the report hope that advertisers will take care over where they spend their money:
"By exposing the end-to-end search spamming activities, we hope to educate users not to click spam links and spam ads, and to encourage advertisers to scrutinize those syndicators and traffic affiliates who are profiting from spam traffic at the expense of the long-term health of the web."