User-mode resource hiding through API interception and filtering is a well-known technique used by malware programs to achieve stealth. Although it is not as powerful as kernel-mode techniques, it is more portable and reliable and, as a result, widely used. In this paper, we describe the design and implementation of a fast scanner that uses a cross-view diff approach to detect all user-mode hiding Trojans and rootkits. We also present detection results from a large-scale enterprise deployment to demonstrate the effectiveness of the tool