The file extension denotes a Google Chrome Extension file. Specifically, idmgcext.crx is the "IDM Integration Module."
idmgcext.crx is a (CRX format) associated with Internet Download Manager (IDM) . It is not malware by default but can raise red flags if found outside a legitimate IDM installation. idmgcext.crx
idmgcext.crx is the Google Chrome extension package name for the Internet Download Manager (IDM) browser integration add-on; it enables IDM to capture downloads from the browser. It’s useful if you use IDM, but be cautious about source, compatibility, and permissions. The file extension denotes a Google Chrome Extension file