Many internet users know that social media companies track both users and non-users. The Electronic Frontier Foundation (EFF) updated its Privacy Badger browser add-on to help consumers fight a specific type of surveillance technology called "Link Tracking," which facebook and many social networking sites use to track users both on and off their social platforms. The EFF explained:
"Say your friend shares an article from EFF’s website on Facebook, and you’re interested. You click on the hyperlink, your browser opens a new tab, and Facebook is no longer a part of the equation. Right? Not exactly. Facebook—and many other companies, including Google and Twitter—use a variation of a technique called link shimming to track the links you click on their sites.
When your friend posts a link to eff.org on Facebook, the website will “wrap” it in a URL that actually points to Facebook.com: something like https://l.facebook.com/l.php?u=https%3A%2F%2Feff.org%2Fpb&h=ATPY93_4krP8Xwq6wg9XMEo_JHFVAh95wWm5awfXqrCAMQSH1TaWX6znA4wvKX8pNIHbWj3nW7M4F-ZGv3yyjHB_vRMRfq4_BgXDIcGEhwYvFgE7prU. This is a link shim.
When you click on that monstrosity, your browser first makes a request to Facebook with information about who you are, where you are coming from, and where you are navigating to. Then, Facebook quickly redirects you to the place you actually wanted to go... Facebook’s approach is a bit sneakier. When the site first loads in your browser, all normal URLs are replaced with their l.facebook.com shim equivalents. But as soon as you hover over a URL, a piece of code triggers that replaces the link shim with the actual link you wanted to see: that way, when you hover over a link, it looks innocuous. The link shim is stored in an invisible HTML attribute behind the scenes. The new link takes you to where you want to go, but when you click on it, another piece of code fires off a request to l.facebook.com in the background—tracking you just the same..."
Lovely. And, Facebook fails to deliver on privacy in more ways:
"According to Facebook's official post on the subject, in addition to helping Facebook track you, link shims are intended to protect users from links that are "spammy or malicious." The post states that Facebook can use click-time detection to save users from visiting malicious sites. However, since we found that link shims are replaced with their unwrapped equivalents before you have a chance to click on them, Facebook's system can't actually protect you in the way they describe.
Facebook also claims that link shims "protect privacy" by obfuscating the HTTP
Refererheader. With this update, Privacy Badger removes the
Refererheader from links on facebook.com altogether, protecting your privacy even more than Facebook's system claimed to."
Thanks to the EFF for focusing upon online privacy and delivering effective solutions.