Fake Virtual Box BIOS Time

Some Windows software in my virtualized Windows XP machine stopped working the other day. It says that the validity period is over. Okay that should not be too hard to get around this issue. As the machine is running on a VBox anyway I looked for some solution to fake the BIOS time - and found something:

$ VBoxManage modifyvm "Windows Testsystem" --biossystemtimeoffset -126489600000

That simly changes the offset from the system time to the virtualized BIOS time. Note: It takes milliseconds as an argument. As I needed the time to be some 4 years a ago I calculated: 60*60*24*366*4*1000. That results in:

Faked System Time in Windows XP