There are lots of other techniques that malware families can use to detect virtualized environments, such as the following:
- Connecting to VirtualBox inter-process communication: \\.\pipe\VBoxTrayIPC
- Detecting other virtualization software files, such as VBoxHook.dll
- Detecting their window title or window class name, such as VBoxTrayToolWndClass or VBoxTrayToolWnd
- The MAC address of their network adapter
This list can be further expanded with many similar techniques and approaches for detecting a virtualized environment.