Characterizing Pixel Tracking through the Lens of Disposable Email Services Authors: Hang Hu, Peng Peng, Gang Wang Department of Computer Science, Virginia Tech {hanghu, pengp17, gangwang}@vt.edu COMPSCI 726: Network Defence and Countermeasures Presented by David Zhai

Introduction and Background

Motivation Understand the disposable email services (DES) and the risks - Collect data from seven popular DES for three months Use DES to collect large-scale email dataset for measuring Email Tracking - Tracking pixel Picture resource: https://www.smarsh.com/connectors/email

Disposable Email Services (DES) Provide temporary email addresses No sign up or password required User-specified address (UA) or Randomly-assigned address (RA) Shared by multiple users Automatically delete after a short period (e.g. one hour)

One Example of DES Picture resource: https://www.guerrillamail.com

Solution and Analysis

DES Data Collection 70K Inboxes 210K Domains 2.3M Emails 10K popular usernames: “info” “John” “admin” “mail” “David” … 7 popular disposable email services 70K Inboxes 210K Domains 2.3M Emails 3 months

DES Analysis Categories of Disposable Emails Account Registration Password Reset Authentication Spam Categories of Email Senders Top 10 categories of the email sender domains for Account Management and Spam Emails Usage Register accounts (Gaming, social network) Obtain free goods (Demos, documents, free Wi-Fi)

DES Risks Disposable email services do not remove emails as quickly as promised Personally Identifiable Information (PII) in emails Credit card number Social security number (SSN) Employer identification number Online accounts registered by DES can be hijacked through a password reset

1x1 tracking pixel, usually hidden Pixel Tracking A common method – Small image at end of email, usually transparent 1x1 pixel Tracking information When Where Who What device Why tracking For business, e.g. advertisement Phishers 1x1 tracking pixel, usually hidden

Email Tracking Detection and Analysis Extract HTML image tags and corresponding URLs of a given email Third-party tracking is highly prevalent Marketing services have the highest ratio of tracking.

Contribution and Criticism

Contribution First measurement study on disposable email services Introduced DES and risks Collected big dataset and analysed messages content Analysed Email Tracking activities Characterizing tracking pixels Insights into the prevalence of tracking Valuable for developing anti-tracking tools for email systems

Criticism DES understanding – Could be extended Measurement – Incomplete scope (Based on User-specified Addresses) About the risk: Online accounts registered by DES can be hijacked through a password reset? – Not exactly DES email is not representative – Not real user Analyses mainly based on Spam Emails – Not accurate result

Thank you!