Will using an on screen keyboard stop keyboard loggers and hackers?

When you type a key on your keyboard, typically a microprocessor within the keyboard does its magic to send a signal up the cable connecting your keyboard to your computer.

And there we reach the very first point of vulnerability. No, not the microprocessor in the keyboard (possible, I suppose, but exceptionally unlikely), but the cable. Or rather what the cable plugs into. Particularly lucrative targets are public computers, where someone comes along and actually installs a physical device between the computer and keyboard; a device that logs every keystroke entered. Sometime later they come back, remove the device and take with it all the information that users of that computer might have entered.

As it turns out, wireless keyboards are worse. Wireless keyboards actually broadcast the keystrokes you're typing. Any receiver within range can "listen in" and record them, and unfortunately "in range" also turns out to be much further than most people think - particularly for a thief with equipment dedicated and tuned to this purpose. While the keystrokes are supposedly encrypted, I recently heard that this encryption is often very easy to crack.

The good news is that your on screen keyboard actually does protect you against these two specific types of keyboard related threats. By using the on screen keyboard you've avoided touching the actual keyboard you've bypassed any compromise of the hardware.

The bad news is that hardware based keyloggers are rare. Much more common are software based threats.

Once your keystrokes arrive at the computer from the keyboard, they are then processed by a keyboard device driver which (to oversimplify) handles the translation of the keyboard "scan codes" that have come over the wire to the letters, numbers and symbols that Windows applications expect. Keystroke loggers typically insert themselves into the receiving end of this process, so that they get the keystrokes from the keyboard as they are passed on to Windows.

This is where the on screen keyboard scenario gets interesting.

The on screen keyboard application is a "virtual" keyboard. It effectively has its own device driver, and to Windows "looks like" a real keyboard. As a result, the keystrokes it sends onto Windows can quite easily be captured by the same key logging software that's capturing keystrokes from the real keyboard, if that key logger has installed itself into the proper place.

But it gets worse. Much worse, actually.

Let's assume that the keystroke logger is not able to capture the keystrokes from the virtual on-screen keyboard.

A keystroke logger can capture a lot more than just keystrokes, so perhaps it'll capture something else instead.

You use the virtual keyboard by using your mouse to point and click at the image of a key on the keyboard. A keystroke logger could then capture on every mouse click:

• the location of the mouse on the screen

• a screen shot image of the screen, or just the area "around" the mouse pointer

What the key logger has done is captured a series of images showing exactly where you clicked and in what order. In other words, it's captured your virtual keystrokes.

Note that this approach to key logging also bypasses one of the more common so-called security techniques of randomizing the keyboard layout on the screen. You still have to be able to see where to click, and the logger simply logs what you see and where you click, regardless of how the keyboard is laid out.

How big a threat is this?

It depends on whom you ask. In my opinion "normal" keystroke loggers - those that record only keystrokes - are a fairly common threat, and are one part of the reason that anti-malware protection and general internet safety common sense in general is so important. So yes, they're out there.

The real question is how pervasive are these more sophisticated screen capturing keyloggers? It's hard to say, but we do know that malware creators have continued to escalate their attacks, both in technique and in scope. It wouldn't surprise me to see these types of malware increase in frequency.

And I, personally, wouldn't rely on a virtual keyboard of any sort as a security measure.