The fact that BitLocker, the data protection technology introduced in Windows Vista Enterprise and Ultimate and in Windows Server Longhorn can be bypassed is not an item of novelty. The issue has been around since the testing phase of the operating system, but Microsoft failed to find a necessary remedy. Still, the scenario for a successful workaround is a tad far fetched. This however does not exclude a successful bypass.

This is why Microsoft security expert Michael Howard delivered a real-world tip to ensure that BitLocker stays in place. The problem is related to the way laptops running either Windows Vista Enterprise or Ultimate handle the Sleep/Stand By modes in relation to BitLocker.

Microsoft has introduced BitLocker as a means to protect the data on lost or stolen PCs. Drive encryption and the integrity checking of early boot components are two of BitLocker's sub-functions that ensure the data remains encrypted.

BitLocker will prevent unauthorized access to the encrypted Windows volume. All the users and the system files on a machine are protected, even the swap and hibernation files.

But a Windows Vista Ultimate or Enterprise that is recovering from Sleep Mode, will only prompt the users for the log-on credentials and nothing more. "So what I do, is put the machine into Hibernate mode; the mode that writes RAM contents to disk and I have implemented BitLocker so the it requires me to enter a pre-boot PIN," Howard revealed.

In this scenario, the user that wakes up Vista from hibernate is also prompted for the BitLocker PIN. And the Trusted Platform Module at the basis of BitLocker will not go down as easy as it seems. "They could try to guess the PIN but the TPM is used to unlock the disk and has anti-hammer technology built into it. After every n failed attempts the TPM goes to sleep for x seconds - and x increases exponentially. The BitLocker recovery model works fine without the PIN should I forget it in my old age! Sure, Hibernate is a little slower than Sleep, but it does have the advantage of requiring no power, and it could help protect your ass(ets) when you use BitLocker," Howard added.