Thursday, December 22, 2016

How to check if your library is leaking catalog searches to Amazon

I've been writing about privacy in libraries for a while now, and I get a bit down sometimes because progress is so slow. I've come to realize that part of the problem is that the issues are sometimes really complex and  technical; people just don't believe that the web works the way it does, violating user privacy at every opportunity.

Content embedded in websites is a a huge source of privacy leakage in library services. Cover images can be particularly problematic. I've written before that, without meaning to, many libraries send data to Amazon about the books a user is searching for; cover images are almost always the culprit. I've been reporting this issue to the library automation companies that enable this, but a year and a half later, nothing has changed. (I understand that "discovery" services such as Primo/Summon even include config checkboxes that make this easy to do; the companies say this is what their customers want.)

Two indications that a third-party cover image is a privacy problem are:
  1. the provider sets tracking cookies on the hostname serving the content.
  2. the provider collects personal information, for example as part of commerce. 
For example, covers served by Amazon send a bonanza of actionable intelligence to Amazon.

Here's how to tell if your library is sending Amazon your library search data.


You'll need a web browser equipped with developer tools; I use Chrome. Firefox should work, too.

Log into They will give you a tracking cookie that identifies you. If you buy something, they'll have your credit card number, your physical and electronic addresses, records about the stuff you buy, and a big chunk of your web browsing history on websites that offer affiliate linking. These cookies are used to optimize the advertisements you're shown around the web.

To see your Amazon cookies, go to Preferences > Settings. Click "Show advanced setting..." (It's hiding at the bottom.)

Click the  "Content settings.." button.

Now click the "All cookies and site data" button.

in the "Search cookies" box, type "amazon". Chances are, you'll see something like this.

I've got 65 cookies for ""!

If you remove all the cookies and then go back to Amazon, you'll get 15 fresh cookies, most of them set to last for 20 years. Amazon knows who I am even if a delete all the cookies except "x-main".

Test the Library

Now it's time to find a library search box. For demonstration purposes, I'll use Harvard's "Hollis" catalog. I would get similar results at 36 different ARL libraries, but Harvard has lots of books and returns plenty of results. In the past, I've used What to expect as my search string, but just to make a point, I'll use Killing Trump, a book that Bill O'Reilly hasn't written yet.

Once you've executed your search, choose View > Developer > Developer Tools

Click on the "Sources" tab and to see the requests made of "". Amazon has returned 1x1 clear pixels for three requested covers. The covers are requested by ISBN. But that's not all the information contained in the cover request.

To see the cover request, click on the "Network" tab and hit reload. You can see that the cover images were requested by a javascript called "primo_library_web" (Hollis is an instance of Ex Libris' Primo discovery service.)

Now click on the request you're interested in. Look at the request headers.

There are two of interest, the "Cookie" and the "Referer".

The "Cookie" sent to Amazon is this:
skin=noskin; session-token="bcgYhb7dksVolyQIRy4abz1kCvlXoYGNUM5gZe9z4pV75B53o/4Bs6cv1Plr4INdSFTkEPBV1pm74vGkGGd0HHLb9cMvu9bp3qekVLaboQtTr+gtC90lOFvJwXDM4Fpqi6bEbmv3lCqYC5FDhDKZQp1v8DlYr8ZdJJBP5lwEu2a+OSXbJhfVFnb3860I1i3DWntYyU1ip0s="; x-wl-uid=1OgIBsslBlOoArUsYcVdZ0IESKFUYR0iZ3fLcjTXQ1PyTMaFdjy6gB9uaILvMGaN9I+mRtJmbSFwNKfMRJWX7jg==; ubid-main=156-1472903-4100903;
Note that Amazon can tell who I am from the x-main cookie alone. In the privacy biz, this is known as "PII" or personally identifiable information.

The "Referer" sent to Amazon is this:
To put this plainly, my entire search session, including my search string killing trump is sent to Amazon, alongside my personal information, whether I like it or not. I don't know what Amazon does with this information. I assume if a government actor wants my search history, they will get it from Amazon without much fuss.

I don't like it.


[I wrote a rant; but I decided to save it for a future post if needed.] Anyone want a Cookie?

Notes 12/23/2016:

  1. As Keith Jenkins noted, users can configure Chrome and Safari to block 3rd Party cookies. Firefox won't block Amazon cookies, however. And some libraries advise users to not to block 3rd party cookies because doing so can cause problems with proxy authentication.
  2. If Chrome's network panel tells you "Provisional headers are shown" this means it doesn't know what request headers were really sent because another plugin is modifying headers. So if you have HTTPS Everywhere, Ghostery, Adblock, or Privacy Badger installed, you may not be able to use Chrome developer tools to see request headers. Thanks to Scott Carlson for the heads up.
  3. Cover images from Google leak similar data; as does use of Google Analytics. As do Facebook Like buttons. Et cetera.
  4. Thanks to Sarah Houghton for suggesting that I write this up.