Google says it’s rolling out a series of search algorithm changes that “aggressively” target the presence of hacked spam in its search results.
Ning Song, the engineer who wrote today’s blog post, says Google is turning up the dial in its algorithms to remove hacked sites from Google’s search results:
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.
Hacked sites are a long-running and common problem on the Web, which makes them a problem for Google, too. Earlier this year, the IT security company Sophos announced that it had notified Google of “hundreds of thousands” of high-ranking, cloaked PDF documents on hacked websites. In 2013, Google revealed that hacked sites were the second most common cause of manual actions. Around that same time, Google launched a help center for hacked sites that’s still online today.
Google is encouraging webmasters, site owners and SEOs with questions or feedback to speak up in the Webmaster Help Forums.
Postscript by Barry Schwartz: Google’s Gary Illyes confirmed that this algorithm typically impacts only the realm of “spammy queries” and not generic normal queries.