This is a Virtual Machine icon. We've made it in iOS style, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 12,300 icons, all in the same style and quality.
The virtual machine has two frames with one frame on top of and slightly offset to the south east of the other one. Each frame consists of an inner rectangle and an outer rectangle with rounded edges with a slight gap between the two rectangles.