New evasion encyclopedia shows how malware detects virtual machines...
[bleepingcomputer.com]

A new Malware Evasion Encyclopedia has been launched that offers insight into the various methods malware uses to detect if it is running under a virtual environment.

To evade detection and analysis by security researchers, malware may check if it is running under a virtualized environment such as virtual machine in VirtualBox and VMWare.

If these checks indicate that it is being run in a VM, the malware will simply not run, and in some cases, delete itself to prevent analysis.