Researchers reverse-engineer Meta Pixel configurations, finding 98.4% default-driven tracking on health sites and Core Setup covering only 34.3% while being bypassable via hashed URLs
The study introduces PixelConfig, a differential-analysis framework that reverse-engineers Meta Pixel configurations through code-patching replays and developer-account controlled experiments, and uses Internet Archive's Wayback Machine to longitudinally compare configurations on 18K health websites against a top-10K control group from 2017 to 2024, finding that default-enabled tracking features such as automatic events and first-party cookies reached adoption rates up to 98.4%, that health websites show tracking of potentially sensitive information tied to booking medical appointments and button clicks associated with specific conditions such as erectile dysfunction, and that restriction features like Core Setup were configured on 34.3% of health websites versus 8.