Google announced the launch of a new hacked site algorithm with the aim to help users and webmasters from hacked spam both in websites and Google search results. It is observed that in the last few months there is an increase in website hacking by spammers affecting most of the legitimate sites and used to engage in traffic to low-quality and illegal products websites or malware downloads etc.
The legitimate sites affected are Government, Education, Hotels, Shopping, and Blogs, etc. This happened because webmasters or site owners do not follow standard best practices for security and leave their websites vulnerable to being easily hacked. WordPress and Cpanel are the main areas where hackers attacked.
Matt Cutts also tweeted that
Google is launching some improvements for hacked sites
Google has spotted such websites and cannot penalize as webmaster or site owner are ignorant about this hacking. Hackers and cybercriminals compromised the sites and inject low quality pages or redirect to again the traffic to low quality pages or websites.
The new hacked sites algorithm will affect 5% of search queries which are pretty high and will be rolled out continuously. You will see that in the case of certain queries on search results you may not see the all results but a few. For example, Google shows 10 results per page but in case the search queries are consist of hacked pages you may see less than 10 i.e 5 or 6 pr 7.