It’s not a matter of a ‘claim’…it’s in the TOS.
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It turns out that this is not a hacked site. It is content that is injected by a plugin called 404 to 301 plugin which has 70,000 active installs and has a 4.5 star review from 56 reviewers. When you install the plugin it asks you to agree to a long agreement which includes parts of the GNU general public license. But at the end it also includes the following text (you have to scroll down to find it):
Third Party Text Links
Third party text networks supply text for display in 404 to 301. These networks may collect your visitors’ IP addresses, in native or hashed forms, for purposes of controlling the distribution of text links. 404 to 301 collects anonymous aggregated usage statistics.
By clicking the button here below, you agree to the terms and conditions and give permission to place text links on your website when search engine crawlers access it. Your website’s layout, performance and interaction with human visitors should not be altered or affected in any way. Please note that this feature can be deactivated at any time under 404 to 301 Setting > Help & Info > Plugin Information > Disable UAN, without affecting any other feature available in 404 to 301.