What about fake virus warnings on Android...
that simulate system warnings that link to dodgy antivirus/cleaner apps served up by AppNexus?
REDACTED_DECODED_BASE_64_SAMPLE_rd..nym1-ib\.\adnxs\.\com
https://www.theguardian.com/technology/2012/apr/23/adnxs-tracking-trackers-cookies-web-monitoring