While some webmasters have set up their mobile version of the site to redirect to a separate page, rather than the same page as desktop, usually as a m.example.com or example.com/mobile/ structure, Google is warning some webmasters that they need to ensure those redirects are actually redirecting users to the correct page and website.

Google has published a new blog post on multiple non-English Google Webmaster Blogs (Portuguese and German)  about these so-called “sneaky redirects”.  It is bringing attention that some mobile sites may be actually redirecting users to a completely different website rather than the intended page, often as a result of a site being hacked.

For those concerned about sending traffic to pages with non-identical, but similar content, that isn’t what Google is concerned about.  When Google’s Gary Illyes previously warned about webmasters redirecting users to the wrong page, he confirmed they are not looking for differences where a user gets slightly different content on mobile, usually because it is slightly abbreviated compared to the matching desktop page. He used the example of “more like ‘adopt this puppy’ on the desktop, and ‘buy Viagra online in a casino without prescription’ on mobile” as what types of mis-match between desktop and mobile that they are concerned about.

But we do also know that Google ranks the desktop version of a page, even when they are sending a user to a different mobile URL of the supposed identical page, although they do check for discrepancies between the two.  So this is likely contributing to the issue of mobile users being directed to completely different pages, since Google ranks and displays snippets based on what the desktop page says, regardless of whether the user is on mobile or not.

Google is considering a separate mobile index which would solve this issue.  The separate mobile index may never happen though, but it would solve some of these types of issues if they do go forward with the separate mobile index in the future.

Their blog post does raise the question about they fact they may be seeing this more in conjunction with hacked sites and as a result of the hacking, mobile users are being sent to the wrong URL.  They specifically mention hacked sites as a problem and that some hacked sites are creating redirects specifically for mobile users.

Since most website owners tend to check the desktop version of a site much more regularly than they do the mobile version, it is easy to see how a hacker could make changes to the mobile pages or redirects only, and the website owner may not notice for some time.

It is likely that there is also a problem with webmasters doing this deliberately for spam reasons.  Google also says that they will take manual action for webmasters who are “deliberately misleading forwarding rules for mobile users” as it violates the Google Webmaster Guidelines.

They also say the other problem with redirects they are seeing is when advertising programs are forwarding mobile users maliciously.  This is an old problem, and something we do see on desktop too.  But some will essentially “take over” the visitor’s web experience by forwarding them to a completely different site, often in spammy market areas, rather than simply serve the ad on the page they visit.

Here is what Google recommends for ensuring your mobile site isn’t having these problems

Check the mobile site from Google results page

Google is recommending site owners not only check their websites on a mobile device, but that they also do so by clicking through to the site from the Google search results.  This also raises the question that perhaps Google is seeing these redirects specifically for Google referral traffic, which would also be harder to spot by a webmaster who visits their mobile site directly by typing in the URL.

Changes in time on site by mobile users

They also suggest using analytics data to check and see if mobile users are suddenly spending much less time than usual on the mobile pages.  This is also a sign that there could be some sneaky redirects happening.  They recommend adding a Google Analytics alert for noticing a change in this mobile user pattern.

Checking for hacked site warnings in Google Search Console

It is always good to check for warnings when you log into Google Search Console – and to enable email alerts for those warnings.  Google will show a warning if it detects a hacked site issue.

Check third party scripts

If you are using a third party script, especially one that calls from a third party site rather than a third-party script you self-host, make sure it isn’t doing any malicious behavior that can impact your site.  If you see one, they recommend removing all of these scripts, then adding them back one by one to determine which script is the issue.

Listen to visitors

Sometimes visitors will give feedback if they have a poor redirect experience on a site, so if you start getting complaints, definitely look into it.

We will update this story when they release an English version of the page, although we have sometimes seen Google with blog posts about issues that are language or location specific only.

Added: Here is the English blog post.