This comes as no surprise to anyone in our field that when Google published their State of Website Security in 2016 they documented that there was a 32% increase year (2016) over year (2015) of sites that got hacked. Google said they don't expect this trend to slow, in fact, they believe there will be even more hacked sites next year.
Google wrote:
First off, some unfortunate news. We’ve seen an increase in the number of hacked sites by approximately 32% in 2016 compared to 2015. We don’t expect this trend to slow down. As hackers get more aggressive and more sites become outdated, hackers will continue to capitalize by infecting more sites.
Although, Google did share two key points on why it is helpful to register with Google Search Console around hacking:
(1) 84% webmasters who do apply for reconsideration are successful in cleaning their sites.
(2) 61% of webmasters who were hacked never received a notification from Google that their site was infected because their sites weren't verified in Search Console.
So even more of a reason to register with Google Search Console. Obviously, many of the sites that do not spend the time registering and verifying their site with Search Console are those who don't have time to care about if their site is hacked or not.
Here are the more common hacks according to Google:
Gibberish Hack: The gibberish hack automatically creates many pages with non-sensical sentences filled with keywords on the target site. Hackers do this so the hacked pages show up in Google Search. Then, when people try to visit these pages, they’ll be redirected to an unrelated page, like a porn site. Learn more on how to fix this type of hack.
Japanese Keywords Hack: The Japanese keywords hack typically creates new pages with Japanese text on the target site in randomly generated directory names. These pages are monetized using affiliate links to stores selling fake brand merchandise and then shown in Google search. Sometimes the accounts of the hackers get added in Search Console as site owners. Learn more on how to fix this type of hack.
Cloaked Keywords Hack: The cloaked keywords and link hack automatically creates many pages with non-sensical sentence, links, and images. These pages sometimes contain basic template elements from the original site, so at first glance, the pages might look like normal parts of the target site until you read the content. In this type of attack, hackers usually use cloaking techniques to hide the malicious content and make the injected page appear as part of the original site or a 404 error page. Learn more on how to fix this type of hack.
Please take care of your site.
Forum discussion at Google+ and Twitter.
Source: Search Engine Roundtable