An overlay can separate the target a user sees from the transaction they approve. Defenses should protect both the visibility of sensitive fields and the actual business approval.
Evaluation approach
Assess obscured screens, unauthorized interaction and application focus in their risk context. Account for legitimate helper applications too.
Application example
If the recipient-change screen is obscured, pause the operation and offer a clear retry path.
Limits and considerations
A generic unsafe-device warning may not help the user resolve the issue.
Displayed content and approved operations
If displayed information changes, pressing the intended button may produce an unintended result. For high-impact operations, make the approved amount, recipient and purpose explicit. The server verifies that transaction binding.
Overlay detection may help, but not every window is malicious. Test legitimate helper tools and manufacturer interfaces. When blocking, make it clear that the operation did not complete and explain how to proceed safely.
Checks and decisions
- Choose sensitive screens
- Write understandable warnings
- Test assistive tools
The goal is to match approval to the correct operation, not to blame the user.
Sources
The primary references above provide the technical basis. Example workflows and evaluation suggestions are this publication’s explanations, not independent test results for a particular product.