Webmasters and bloggers: make sure the widgets on your site don't have unnatural links
There are some website widgets - hit counters, visitor maps, stock prices, news updates, facts of the day and so forth - that have hidden low quality links. Google recommends you add a rel="nofollow" attribute on those unnatural links or remove the links entirely from the widget.
And if you are a website owner, make sure that a widget with links back to your site has the rel="nofollow" attribute, otherwise Google could penalize your site in the search results.Widgets can help website owners enrich the experience of their site and engage users. However, some widgets add links to a site that a webmaster did not editorially place and contain anchor text that the webmaster does not control. Because these links are not naturally placed, they're considered a violation of Google Webmaster Guidelines.
---Google's webspam team may take manual actions on unnatural links. When a manual action is taken, Google will notify the site owners through Search Console. If you receive such a warning for unnatural links to your site and you use links in widgets to promote your site, we recommend resolving these issues and requesting reconsideration.
Learn more on the +Google Webmasters