We’ll start with a nutshell description of GAEN contact tracing, then show what data is logged, and finally explain why this logging is so concerning to us. Recently, we found that Google’s implementation of GAEN logs crucial pieces of information to the system log, which can be read by hundreds of third-party apps and used for the privacy attacks that we previously warned about.

Earlier, we wrote about some attacks that can be done in GAEN-based contact-tracing systems, which is the Google-Apple Exposure Notification system that is used by many countries and regions worldwide to do digitally-assisted contact tracing.