Simple definition
Intune attack surface reduction policies configure Microsoft Defender controls to limit common exploitation techniques.
Purpose and use
An ASR, Attack Surface Reduction, policy limits attack-abused behavior by configuring supported protection features.
How does it work?
Rules can have audit, block or other supported modes; prerequisites depend on the profile and Defender components.
Example and verification
Start with a pilot group and review audit events to identify affected legitimate applications.
Points to watch
An audit-mode rule does not block the observed action. Broad exclusions can also reduce protection across several uses.
In short
Connect intended rules with their effective modes and the application constraints of targeted devices.