A security researcher demonstrates that an Android app with BIND_ACCESSIBILITY_SERVICE can read content from any app on the screen, bypassing the sandboxing model for UI content. Why does this capability exist and what safeguard does Android provide?

• A.A. BIND_ACCESSIBILITY_SERVICE is a normal permission automatically granted to all apps declaring an accessibility service
• B.D. BIND_ACCESSIBILITY_SERVICE is a signature-level permission that prevents third-party apps from using it
• C.C. Android encrypts all screen content using hardware attestation, so accessibility services only receive metadata, not actual text
• D.B. The capability exists to support legitimate assistive technology (screen readers, motor assistance); safeguards include requiring users to explicitly enable each accessibility service in Settings > Accessibility and a system dialog warning that the service can observe screen content