VMQemuVGA.kext, it should work on all OSs from Snow Leopard up to Yosemite 10.10 under VirtualBox
LatestDisable kext signing on OS X Yosemite
To use VMQemuVGA on OS X Yosemite, you need to disable the kext signing security setting. On a physical Mac you would use the following command:
nvram boot-args=kext-dev-mode=1
On a VirtualBox virtual machine the boot-args are stored in .vbox virtual machine settings file:
<ExtraData>
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<ExtraDataItem name="VBoxInternal2/EfiBootArgs" … kext-dev-mode=1 … "/>
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</ExtraData>
You should be careful to only install system drivers from sources that you trust.