Air carrier pilot reported an NMAC with a UAS nearby the aircraft during arrival descent. Pilot stated they have seen other UAS near approach corridors recently and believe UAS pose a growing hazard.

Narrative

During descent to the airfield on the STAR and upon passing 5nm north of the airfield at 4000ft; 250kts; and heading 280 (arrival briefing and appropriate checklists were complete); we descended through scattered clouds when I observed a drone at the base of the clouds. We passed approximately 150ft to the left of the drone and did not alter our intended flight path in any way. The drone was about 2 feet in height; and had a black body with green and red lights on the top. I could not tell how many blades it used. It hung vertically; compared to flat quad-copter style drones commonly used among recreational drone pilots. Once we were established on the localizer and on Tower frequency; the controller asked me for a few more details regarding the drone's appearance and location. To my knowledge; the CA and pilot flying at the time; was only able to briefly see the drone but likely will not be able to provide a detailed description of it. The drone's altitude and precise location on the STAR/radar downwind for the active runway makes me think the user was not simply a recreational pilot; but rather the user placed the drone there deliberately. As a new commercial airline pilot (less than 300 hours); I've now see 2 drones over the past 2 months on or near approach corridors. Overall; this is a growing hazard and until drone activities are more closely controlled and regulated; I suspect accidents and incidents across the aviation industry will increase. I do not have any details regarding the causal factors that placed the drone in that precise location and altitude. Since we did not alter our heading; course; altitude; pitch or bank; I thought the best mitigation at the time was to warn other pilots in the area.