I run a white hat site that does well in the SERPs for its niche. Over the last 6 months a very content-thin site has started to creep up the rankings and out-rank me and other big authoritative sites for certain terms. I look at this sites backlinks with the usual tools (Majestic, Ahrefs, Moz, etc) and don't see anything special though, nothing that should be causing it to rank to highly (by a long shot). Also, the on-site SEO is nothing special. Like based on what I see it should be back in page 5+, not the top 3 of page 1! So I've concluded they are using PBNs and the PBNs are blocking crawlers so I can't see them. Is there anything I can do to see their links and/or compete more effectively with this site?