Bypassing the Windows Lock Screen

Most of us know that we should lock our computers when we step away from them. This will prevent any unauthorized users from gaining access to our files. Most companies have some sort of policy in regards to this, and many even automatically lock the screen after a set amount of time with no activity. In some cases, the computers are configured to lock and display a screen saver. In these cases, it may be possible for a local attacker to bypass the lock screen.

[Adrian] explains that the screen saver is configured via a registry key. The key contains the path to a .scr file, which will be played by the Adobe Flash Player when the screen saver is activated. When the victim locks their screen and steps away from the computer, an attacker can swoop in and defeat the lock screen with a few mouse clicks.

First the attacker will right-click anywhere on the screen. This opens a small menu. The attacker can then choose the “Global settings” menu option. From there, the attacker will click on “Advanced – Trusted Location Settings – Add – Add File”. This opens up the standard windows “Open” dialog that allows you to choose a file. All that is required at this point is to right-click on any folder and choose “Open in a new window”. This causes the folder to be opened in a normal Windows Explorer window, and from there it’s game over. This window can be used to open files and execute programs, all while the screen is still locked.

[Adrian] explains that the only remediation method he knows of is to modify the code in the .swf file to disable the right-click menu. The only other option is to completely disable the flash screen saver. This may be the safest option since the screen saver is most likely unnecessary.

Update: Thanks [Ryan] for pointing out some mistakes in our post. This exploit specifically targets screensavers that are flash-based, compiled into a .exe file, and then renamed with the .scr extension. The OP mentions these are most often used in corporate environments. The exploit doesn’t exist in the stock screensaver.

Physical Keys Not Just For Doors Anymore, Now Available For Windows

Physical Key Locks and Unlocks Windows Computer

If you have ever forgotten your computer password after a long weekend or maybe you can remember it but just can’t seem to type it correctly, [Thomas] has a project for you. It’s a physical key that locks and unlocks your PC.

So how does it work? The heart of the project is an Arduino Leonardo. You may recall that this board is a bit different from the preceding Arduinos as it can enumerate on a host computer as a Human Interface Device (HID), such as a keyboard or mouse. The Arduino sketch continually reads an input pin using an internal pull-up resistor to make it logic high with the key switch connecting the signal to ground. When the Arduino sees the pin change from high to low, it sends out a keyboard command consisting of the Windows Key and “L”, which is the keyboard shortcut for locking the computer.

When the physical key is turned again, the Arduino sees the pin change back to a high state and it again emulates a keyboard but this time enters your password. You do have to include your password in the Arduino sketch for this to work. In addition, there are two LED’s wired up to show if the computer is locked or not, but you’ll be able to tell pretty quick when trying to get back to work.

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Do you know what you’re doing when integrating PC-side apps with USB microcontrollers?

The advent of integrated USB peripherals in microprocessors (PIC, AVR, etc.) has certainly taken a lot of the work out of developing USB devices, not to mention reducing the silicon parts in these designs. But do you know what you’re doing when it comes to controlling them with user-friendly applications? [Simon Inns] is lending a hand with this in his recent tutorial. He shows how to use USB capable AVR chips along with your own Windows applications.

After the break you can see the video from which the above screenshot was captured. That’s a development board of his own making which hosts an ATmega32U4, as well as a USB-B port, LEDs, potentiometer, and a few switches. Taking a closer look, we love the breadboard friendly headers he used on the bottom of the board to break out all of the pins.

His demo shows the Windows app turning LEDs on the board on and off, as well as ADC data displaying the current potentiometer position with the onscreen dial. His code package includes the hardware design, firmware, and app software needed to follow along with what he’s doing.

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Winterizing: keeping the drafts out of double-hung windows

[Rumplestiltskin] has had work done on his double-hung windows to help prevent drafts and keep them in good working order. But there are still a few that rattle, and let in the cold of winter. Not this year; he’s added a small feature to the jamb that will keep out the cold weather.

A pair of jointing blocks were added to each window. The small block seen above is attached to the window jam with a couple of all-purpose screws, and hosts a machine screw which points toward the window frame. Since there is weather stripping between the two window frames, and between the frame and the outer jamb, tightening this screw will snug the frames up to close any small gaps. This has the unintended consequence of prohibiting the window from being opened (unless you don’t mind scraping the paint as the machine screw slides across the wood). But if only used in the winter months this is a viable solution.

GPU password cracking made easy

The power that a Graphics Processing Unit presents can be harnessed to do some dirty work when trying to crack passwords. [Vijay] took a look at some of the options out there for cracking passwords and found that utilizing the GPU produces the correct password in a fraction of the time. On a Windows machine he pitted the Cain password recovery tool which uses the CPU for its calculations against ighashgpu which uses ATI or Nvidia graphics cards to do the deed. Hands down ighashgpu is the fastest; with Cain taking about one year to crack an eight character password while ighashgpu can do it in under nineteen hours.

We were very interested to see how easy it is to use this package. We looked in on GPU cracking in September but didn’t focus on the software packages that are out there. Now that you know how easily your password can be unearthed perhaps you will get some use out of this article discussing the usability and security of longer passwords which we ran across over on Reddit.

BAMF2011: chipKIT is Arduino to the power of 32

If you’ve been hungry for more power for your microcontroller projects, but reluctant to dump your investment in Arduino shields or the libraries and community knowledge that go with them all, Digilent has you covered. Their new chipKIT boards are built around the Microchip PIC32 MCU…a powerful 32-bit chip that until recently was left out of the cross-platform scene. A majority of code and quite a number of Arduino shields will work “out of the box” with the chipKIT, and the familiar development tools are available for all three major operating systems: Windows, Mac and Linux.

We first mentioned these a couple weeks ago, but the software was unavailable at the time. Seeing the development tools in action was quite unexpected…

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Kinect to get Windows drivers months after open source drivers were developed

Microsoft is planning to release Windows drivers for the Kinect this spring, months after open source drivers were developed by a motivated hacking community. [Johnny Chung Lee], who worked with the Microsoft team when the hardware was developed, mentions that he had pushed for the giant to develop and release at least basic Windows drivers. That refusal led him to a position as top cheerleader and bounty contributor in Adafruit’s Open Kinect Contest which resulted (quickly we might add) in the availability of open source drivers. If you’ve been following Hackaday or any other tech blogs the last three months you’ll know that an explosion of projects using the Kinect followed, and [Johnny] figures Microsoft’s decision to release Windows drivers is an attempt to ride this wave on their own flagship OS rather than continue to watch from the sidelines.