Running suspicious software in a virtual machine seems like a basic precaution to figure out whether said software contains malicious code.
Unfortunately, it's generally rather easy to detect whether or not one's software runs inside a VM. A list of ways that a VirtualBox VM can be detected from inside the guest OS is available, including obvious naming issues and more subtle methods.
A Proof of Concept (PoC) 'malware' application called Al-Khaser demonstrates these detection methods and can be used to verify one's anti-malware systems.
Al-Khaser can be used to verify one's anti-malware systems, such as when trying to unleash a debugger on a piece of malware, run it inside a VM.
This application has many uses, including testing the effectiveness of anti-malware systems.
Author's summary: Detecting virtual machines to evade malware analysis.