According to Google, they are rolling out a series of search algorithm changes that will “aggressively” target the presence of hacked spam in search results.
The engineer who wrote the blog post, Ning Song, said that Google is turning up the dial in their algorithms to removed hacked sites from their search results. Here’s a part of the post:
We are aggressively targeting hacked spam in order to protect users and webmasters.
The algorithmic changes will eventually impact roughly 5% of queries, depending on the language. As we roll out the new algorithms, users might notice that for certain queries, only the most relevant results are shown, reducing the number of results shown.
This is due to the large amount of hacked spam being removed, and should improve in the near future. We are continuing tuning our systems to weed out the bad content while retaining the organic, legitimate results.
Unfortunately, hacked sites have been a problem for a long time. They have been a long-running issue on the web, and because they are sites, they’ll, in turn, be an issue for Google as well. Sophos, an IT security company, announced earlier this year that it had notified Google of “hundreds of thousands” of high-ranking, cloaked PDF documents on hacked websites. It was revealed by Google in 2013 that hacked sites were quite the problem, as they were the second most common cause of manual actions. Google launched a help center for hacked sites around the same tie, that is still around and kicking today.
If there are any questions or feed back that you’d like to bring up to Google, they can be reached in the Webmaster Help Forums.