Saturday, July 18, 2009

Update on USB Devices

I posted to the Win4n6 Yahoo Group on USB removable storage devices and tracking connections, and got some really good confirmation from Rob Lee, so I thought I'd share it here, as well.

So, when I was writing WFA 2/e, I did some testing and found that when connecting a USB removable storage device to a system, beneath the unique instance ID key (under the DeviceClasses key), a Control subkey was created, and when the device was disconnected, the Control subkey was deleted. The creation/deletion of this subkey constitutes a modification to the unique instance ID key, updating the key's LastWrite time and allowing us to track the usage of the device.

However, there appear to have been changes to this functionality since then, and Rob's more expansive testing has confirmed my own. Essentially, if you sit down to a running system (XP SP2 or 3, Vista, Windows 7), and plug in a USB removable storage device (even one that's been previously connected to that system), you'll see the Control subkey created...but when you disconnect the device, the Control subkey will remain until the system is rebooted. Rob has confirmed that this LastWrite time survives logins, as well.

So, now the LastWrite time on the unique instance key refers to the time that the device was last connected to the system, which is an important distinction to make when performing analysis of the usage of these devices. This requires further testing for more complete confirmation, but this is how things appear at this time. Shout outs to Rob Lee for the testing on this!


Anonymous said...

Maybe you should put an errata on page 209 of your WFA/2 book..:-) Kudos to Rob and thanks for sharing the info.

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