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Domain-joined Windows computers that use BitLocker should be patched as soon as possible.

Companies relying on Microsoft BitLocker to encrypt the drives of their employees’ computers should install the latest Windows patches immediately. A researcher disclosed a trivial Windows authentication bypass, fixed earlier this week, that puts data on BitLocker-encrypted drives at risk.
Ian Haken, a researcher with software security testing firm Synopsys, demonstrated the attack Friday at the Black Hat Europe security conference in Amsterdam. The issue affects Windows computers that are part of a domain, a common configuration on enterprise networks.
When domain-based authentication is used on Windows, the user’s password is checked against a computer that serves as domain controller. However, in situations when, for example, a laptop is taken outside of the network and the domain controller cannot be reached, authentication relies on a local credentials cache on the machine.
In order to prevent an attacker from connecting a stolen, lost or unattended laptop to a different network and creating a spoofed domain controller that accepts another password to unlock it, the authentication protocol also verifies that the machine itself is registered on the domain controller using a separate machine password.
This additional check doesn’t happen when the controller cannot be reached, because the protocol developers assumed that the attacker can’t change the user password stored in the local cache. However, Haken figured out a way to do it—and it only takes a few seconds if automated.

How it works

First, the attacker sets up a mock domain controller with the same name as the one the laptop is supposed to connect to. He then creates the same user account on the controller as on the laptop and creates a password for it with a creation date far in the past.
When authentication is attempted with the attacker’s password on the laptop, the domain controller will inform Windows that the password has expired and the user will automatically be prompted to change it. This happens before verifying that the machine is also registered on the controller.
At this point the attacker will have the ability to create a new password on the laptop, which will replace the original one in the local credentials cache.
Logging in while connected to the rogue domain controller would still fail, because the controller does not have the machine password. However, the attacker could disconnect the laptop from the network in order to force a fallback to local authentication, which will now succeed because only the user password is verified against the cache.
This is a logic flaw that has been in the authentication protocol since Windows 2000, the researcher said. However, physical access did not used to be part of the Windows threat model, because in such a situation an attacker could boot from an alternative source, like a live Linux CD to access to the data anyway.
That all changed when BitLocker was introduced in Windows Vista. Microsoft’s full-disk encryption technology, which is available in the professional and enterprise editions of Windows, is specifically designed to protect data in case a computer is stolen or lost—in other words when an unauthorized individual has physical access to it.
BitLocker stores the data encryption key in a Trusted Platform Module (TPM), a secure hardware component that performs cryptographic operations. The key is unsealed from the TPM only if the same boot process is followed as when BitLocker was first activated.
The various stages of the boot process are cryptographically verified, so an attacker with physical access to a BitLocker-enabled laptop will not be able to boot from an alternative OS to read the data stored on its drive. The only possibility left for the attacker in this case is to boot normally to unlock the encryption key and then to bypass the Windows authentication to gain access to the data, which Haken’s attack allows.
Microsoft fixed the vulnerability Tuesday and published the corresponding MS15-122 security bulletin.
This attack shows that when it comes to security, we constantly need to reexamine old truths, Haken said.
BitLocker offers the option to enable preboot authentication using a PIN or a USB drive with a special key on it, in addition to the TPM. However, such configurations are a hard sell for enterprises, because they introduce friction for users and make it difficult for administrators to remotely manage computers, Haken said.
In its own documentation, Microsoft admits that preboot authentication is “unacceptable in the modern IT world, where users expect their devices to turn on instantly and IT requires PCs to be constantly connected to the network.”

Source: www.pcworld.com

Maybe you like Google. Or Yahoo. Or DuckDuckGo. Choosing your own search engine just takes a few steps.

Microsoft, of course, would rather you used its Bing search engine in its browser running inside its operating system. But you don’t have to. Even if you’d prefer to stay with Microsoft’s browser, you can change that browser’s default search engine.
I’ll give you instructions for both Internet Explorer 11 and Edge.
[Have a tech question? Ask PCWorld Contributing Editor Lincoln Spector. Send your query to answer@pcworld.com.]

Internet Explorer 11

In Internet Explorer, go to the Internet Explorer Gallery webpage. Scroll down a bit, and you’ll find a block of add-ons. Some of them, such as Google and Yahoo, will be clearly labeled as Search.

 

Here’s the unfortunate part: If your preferred search engine isn’t on this page, you can’t make it your default. You can make Google or Yahoo your default, but not, for instance, the privacy-friendly DuckDuckGo.
Click your preferred search engine (or at least the best in the group). This will take you to another webpage, where you can click the Add to Internet Explorer button.
In the resulting Add Search Provider dialog box, check Make this my default search provider and click Add.

That’s it: you’ve changed Internet Explorer’s Search provider.

Edge

Just about any search engine works here, including DuckDuckGo.
First, go to your preferred search engine’s main page. You don’t have to do anything there. You just have to bring up the page in Edge. Then follow these instructions:
1.   Click the menu icon (three dots) in the top-right corner and select Settings

2.   Scroll down the Settings panel, then find and click the View advanced settings button.
3.   Scroll down the Advanced settings panel to “Search in the address bar with.” Click the pull-down menu. You’ll find two options: Bing and <Add new>. Click <Add new>.

4. Here’ you’ll find all of the search engines you’ve visited. Select the one you want and click Add as default.

That’s it. Edge will now default to your favorite search engine.

Source: www.pcworld.com