Google Blogoscoped

Wednesday, December 6, 2006

Case Study: Hiding a Link

How sneaky – UNESCO (the United Nations Educational, Scientific and Cultural Organization) is using hidden links on their website. If you view their PageRank 7 web forum, you won’t notice anything spammy just by looking at the page. But right-click it in Firefox and select View page info -> Links, and carefully look at the sites linked. You’ll notice the domain “” sticking out somewhat, and when you go back to check the page’s code you’ll see that indeed, the innocent-looking word “troubleshooting” in the forum’s description is a link (see screenshot).

The following HTML was used, likely not by UNESCO but a webmaster trying to abuse UNESCO (their homepage has a juicy PageRank of 9, after all):

<a href="" style="COLOR: #000000; text-decoration: none; cursor: text; font-weight: normal;"
onmousemove="status=’ ’">troubleshooting</a>

Above HTML and inline CSS/ JS translates to: make the link black, don’t underline it, don’t show a special cursor, and try not to display its URL in the status bar – in other words, make the link look like normal text, not a link. And while this may seem obviously evil if you know HTML, Google’s parsers are not necessarily able to detect all such hidden links.

Now, what’s anyway? It’s a PageRank 6 domain owned by Monika Knapp from Germany, with – according to the site’s Google page count – about 6,370 pages displaying bicycle parts affiliate links (’cause while you can browse products on the site, you’ll end up buying them on Whether or not Monika is responsible for the spammy backlink is impossible to tell unless you know who exactly is responsible for setting up the UNESCO web board the way it was set up (for example, anyone can create a hidden link pointing to, which doesn’t make Google employee Matt Cutts a search engine spammer). Which leaves us with a couple of possible explanations for what’s happening here, and why:

  1. UNESCO is secretly selling text links (I don’t think so).
  2. UNESCO considers this link relevant and valuable to its visitors, making this a perfectly “natural” link, that just happens to be styled so that it won’t catch too much attention (don’t think so either).
  3. The webmaster, or someone connected to the webmaster, is also responsible for setting up the UNESCO web board; this person wanted to boost their own affiliate shop in Google rankings, and backlinked to their site, unbeknownst to UNESCO (somewhat more likely).
  4. The webmaster bought backlinks through a service, not knowing that this service is using sneaky methods of abusing the HTML of “positive seed sites” (again, is a PR9 homepage, so it’s definitely “good” in the eyes of Google’s algos).
  5. The UNESCO board came with out-of-the-box templates, and the person creating these templates sells links/ is connected to
  6. didn’t ask for this backlink, but the UNESCO forum developer is creating “camouflage” weblinks to innocent sites to protect their spammy backlinks to not-so-innocent sites with noise; it’s the old concept of hiding a leaf in the forest (somewhat unlikely).

Does gain from this backlink anyway? I’d think so, but that’s hard to tell. In the past, we learned that Google has methods of disabling a page’s power to send linkjuice... without banning that page itself. (For example, that happened with this W3C page, according to Matt Cutts). Whether or not that’s the case with UNESCO can’t be seen from outside the Googleplex, though I bet there’s thousands or millions of undetected spam backlinks on PR7 pages (less so on PR8 pages, and even less on PR9 pages, because their “seed" value is higher, so it’s potentially more destructive and thus worthwhile for Google to manually watch them).

[Thanks JohnMu!]


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