A USENIX Security paper by Asuman Senol (KU Leuven), Gunes Acar (iHub), Mathias Humbert (University of Lausanne) and Frederik Zuiderveen Borgesius (iHub) showed how users’ email addresses and passwords are collected on thousands of websites for tracking purposes without users consent and knowledge. The study was covered by Wired and NOS.


You can have a look at the study website for more information.