A large-scale Android advertising fraud operation named ‘Trapdoor’ used 455 malicious apps distributed through Google Play Store to generate 659 million fraudulent ad bid requests daily, siphoning advertising revenue from brands and media buyers. The campaign affected any organization running programmatic advertising on mobile platforms, with fraudulent installs and attribution data corrupting campaign performance metrics. Google has removed the identified apps; the primary residual risk is financial loss from ad spend already consumed and ongoing exposure if related clusters remain active.