I'm working on an app (Written in C#) that have a setting to run on KIOSK mode. I've just an challenge here which is disabling Ctrl+Alt+Del combination Event.
There is no right answer in the similar past posts. Please let me know about the right action.
Considering, my code is working with registry keys to disable/enable options, if you know any registry key,it will be more helpful.
CTRL+ALT+DEL is the secure attention sequence of Windows NT (and its derivatives like Win7). It is the one key combination that is guaranteed to get the OS's attention. The whole point of the SAS is that it can't be intercepted or stopped by user programs.
One security issue it addresses is that of a false login screen: consider a screen that looks exactly like the normal Windows login screen. There's no way to tell that it's a fake just by looking at it. But, if you're in the habit of always pressing CTRL+ALT+DEL before logging in (there is an option to always require it for the legitimate screen), pressing the SAS on a false login screen will bring up task manager or the secure attention screen (with the log off, change password, etc options). The real login screen doesn't do that; it just stays there on the screen. As long as the OS itself isn't replaced or compromised, CTRL+ALT+DEL will protect you from false login screens. If a user program could intercept the SAS, it wouldn't be worth anything.
The SAS was baked into the Windows NT design right from the beginning (it was in the first release in 1993), so getting around it won't be easy. I'm sure there are keyboard filter drivers-- or something to intercept that sequence-- that are designed for kiosk use.
It is not possible to capture CTRL+ALT+DEL, it is so by design in all Windows systems. This is a security issue, if the user hits CTRL+ALT+DEL, he or she should be certain that it is the operating system and not some application (possibly a password-catching trojan) that responds to it.
I guess to capture CTRL+ALT+DEL you would need to write a device driver of some sorts.
Edit: Also see This answer. I did not try it, but the question is fairly similar.
Although it is sort of possible, it is not an easy task and not something that can be done in C#. This Article will show you how to disable CTRL+ALT+DEL using group policy editor. To permanently disable the combination though, you will either need to write your own keyboard driver or write your own GINA stub (Graphical Identification and Authentication).
It is possible to pick up the CTRL+ALT+DEL combination, but not to disable it.
I tried to disable it with SetWindowsHookEx and WH_KEYBOARD_LL and you can successfully get notified when CTRL+ALT+DEL is pressed, but you cannot do anything about it.
It is possible to block CTRL+ALT+DEL combination. However, you can't really disable it. As far as I know, there are two possible methods.
Remapping the keyboard layout. There is a registry binary key that allows you to remap keyboard layout:
HKLM\System\CurrentControlSet\Control\Keyboard Layout\Scancode Map
Please check this out: Disabling Windows Hot Keys
This method can be dangerous, but I haven't noticed any side effects this method can cause. The CTRL+ALT+DEL combination is handled by winlogon.exe. If your process has administrative privilege, you can suspend winlogon.exe. Hence, it cannot process the hotkey and nothing will happen if the user presses CTRL+ALT+DEL.
Please check this out: C++ code to disable CTRL+ALT+DEL.
You will need to do some P/Invoke, in user32.dll, there's a method called SystemParametersInfo, check out these resources for more info
http://pinvoke.net/search.aspx?search=SystemParametersInfo&namespace=[All]
http://msdn.microsoft.com/en-us/library/windows/desktop/ms724947%28v=vs.85%29.aspx
I did something similar a long while back, but no longer have the code, though I did find this (it's in vb6), but it shouldn't be too hard to get the idea and translate to .NET
http://www.developerfusion.com/code/1021/how-to-disable-ctrlaltdel/
Related
I have to write an application in C# that listens to any keys being pressed. In actuality I have a bar code scanner sending the "key pressed" event, and I need to listen it... what it does from there is beyond the scope of my question.
My security requirements are that there is not allowed to be any sign-on to the machine in any way shape or form AND this must run as a windows service. The user will start the machine and walk away (i.e., no desktop session).
I'm assuming I'm going to have to go unmanaged for this.
Given the security requirements is this even possible? If so, any pointers on where to start would be great.
Thanks in advance,
Jay
Try keyboard and mouse hook
http://www.codeproject.com/KB/cs/globalhook.aspx
You will have to learn pInvoke with combination of learning how to look for the right events produced at the lower level of OS. By calling into user32.dll using pInvoke your managed code can filter those events through the hooks.
http://pinvoke.net/default.aspx/user32.SetWindowsHookEx
If you need to see keyboard presses for all apps, system-wide Hooks would be the way to go normally, but the problem is that the security changes in Vista and above make hooks rather less useful. A process cannot hook another process at a higher integrity level, so there's no guarantee you will see all events.
However if you only need to see events going to a particular app - the one reading the bar codes - then provided you can identify that process, a thread-specific hook will suffice and the integrity question will not arise.
I have to run my C# application that I wrote it recently on several computers with window 7 operating system. Here is a big challenge with it, Application must run on startup and user must not be able to work with anything else such as windows hotkeys, other applications, some directories and etc.
Considering I don’t want to kill any process or service as less as possible, Please give me the best solution.
Thanks and waiting
Maybe A little more information will help
did you see Devices like ATMs or Medical devices that window is running on? Those devices don't allow user to manipulate with desktop or anywhere else, I want their solution. . . my Application Will run as a device handler(A Medical Device in Operating room).
You probably shouldn't write such an application in the first place (nagware?).
Anyway. I think what you are looking for is actually "kiosk" software. Here is blog entry that describes how to lock down the computer to effectively run in "kiosk mode".
Note however, that not every application can (or should) be used in that mode. Either because it has loopholes that still allow you to do thing (for example the file open/save dialog still allows you to create directories or navigate the file system), or because they were simply not designed with that goal in mind.
This sounds actually like a (very) bad idea to me...
You could probably hook every Keyboard event so you disable OS shortcut (Windows + D, Windows + E...). See here.
Also hide the Windows taskbar.
Make sure your application starts with Windows.
This sounds a bit hacky to me...
A program with the properties you mention is called a (very restrictive flavour of) shell. So you need to register your program as a shell (instead of explorer.exe) for the poor, poor user you want to restrict.
You might look into using a local group policy to enforce this restriction. Check this out.
At my workplace, I need to create a questionnaire that is compulsory for the user to fill out. The aim is to make it as non-intrusive to the user as possible and link it to their Windows account. The results will then be stored in a database where reports can be generated off of the responses.
The suggestion was to load the questionnaire at login time, i.e. when the user logs onto the computer. I would have to make the window exclusive so that no other windows could be interacted with.
My question how would I go about doing this? Could this be done with WPF or would I need XNA or something similar?
Also, are there any other suggestions on how I could meet all the criteria with a different implementation?
Is there a way to run/activate an application at screen unlock?
You can create an app with WinForms or WPF. I don't know about XNA. :) And you can load it on startup; by using Registry. You may need to manually disable ALT + Tab, using API, to disable the interaction between other windows.
First off, it appears you may have conflicting requirements - "non-intrusive" and "compulsory" - to a user any interruption can be considered a violation of their sacred time :)
I would use a Maximized WPF Window that allows transparency, has no window style, fairly transparent to look like the background is disabled. The "form" area would be centered on the screen. The form, once filled out, would close and set a per-user state in a settings.config file to ensure the next time the user logs in it doesn't show up again.
Anuraj has it right to attempt to disable as much interaction as possible via the supression of special keystrokes.
I would suppress the keystrokes by marking the KeyEventArgs as handled upon the raising of the PreviewKeyDown event.
I've never done this on multiple monitors, though, don't know how that would look.
Compulsory is done by, as you say linking it to their domain accounts, and then giving anyone a written warning who has not completed the questionnaire in some time frame.
If you are not willing to back your "compulsory" requirements with actual discipline procedures then implementing technical obstructions is a waste of time. With discipline procedures in place, technical obstructions are unnecessary to achieve compliance.
The actual implementation would probably be best done on the corporate intranet server as a web-form.
This of course requires that the company is mature enough to be using a central login server of some kind (domain controller if windows) and has a corporate intranet.
Now is a good time to start perhaps.
I have to write an application in C# that listens to any keys being pressed. In actuality I have a bar code scanner sending the "key pressed" event, and I need to listen it... what it does from there is beyond the scope of my question.
My security requirements are that there is not allowed to be any sign-on to the machine in any way shape or form AND this must run as a windows service. The user will start the machine and walk away (i.e., no desktop session).
I'm assuming I'm going to have to go unmanaged for this.
Given the security requirements is this even possible? If so, any pointers on where to start would be great.
Thanks in advance,
Jay
Try keyboard and mouse hook
http://www.codeproject.com/KB/cs/globalhook.aspx
You will have to learn pInvoke with combination of learning how to look for the right events produced at the lower level of OS. By calling into user32.dll using pInvoke your managed code can filter those events through the hooks.
http://pinvoke.net/default.aspx/user32.SetWindowsHookEx
If you need to see keyboard presses for all apps, system-wide Hooks would be the way to go normally, but the problem is that the security changes in Vista and above make hooks rather less useful. A process cannot hook another process at a higher integrity level, so there's no guarantee you will see all events.
However if you only need to see events going to a particular app - the one reading the bar codes - then provided you can identify that process, a thread-specific hook will suffice and the integrity question will not arise.
How can I disable Print Screen functionality while my WPF application is running?
The use-case is that my client wants to avoid unnecessary replication of valuable patient-centric data from the outside world and they provide the physical security to keep people from taking data through non-digital means.
Okay, it is possible, and could indeed be useful if your application is deployed in an environment where a camera is not available to the user.
First of all, I used the RegisterHotKey and UnregisterHotKey API calls, documented here http://pinvoke.net/default.aspx/user32.RegisterHotKey as described in this rather old article here http://msdn.microsoft.com/en-us/magazine/cc163713.aspx.
I registered the IDHOT_SNAPDESKTOP hotkey in the Window_Load event and unregistered it in the Window_Closed. Trying to do this in the constructor gave me problems getting a consistent handle with the WindowInteropHelper(this) method.
If you'd like to do more than just ignore the keys you can set up a windows message handler, making a kind of WndProc using,
HwndSource source = HwndSource.FromHwnd(<handle>);
source.AddHook(<WndProc>);
making the handle as described above, and the WndProc implementation yourself.
As yet, I don't know how to "not" handle the hot key and get windows to perform its normal behaviour except, of course, by unregistering the hotkeys.
Its not very elegant or "WPF" but it worked for me.
As #ghord comments
The use of EnsureHandle() looks useful for getting a handler in the constructor.
It's not possible to disable printing, and even if it were possible, it would be easily circumvented by a cell phone camera. Many are in the megapixel resolution range, making it quite easy for someone to get the information they want.
If you want to disable the Print Screen Key on your keyboard, Jodrell's answer gives a way of doing that (understanding that it's not going to keep people from printing, and a determined user will find a way around that).
Really, it all comes down to trust. If an employer can't trust their employees not to remove data that is already protected by law in most jurisdictions (HIPAA in the USA), then there's a bigger issue at stake.
Easy:
Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().IsScreenCaptureEnabled = false;
Simply speaking, you cannot. "Print screen" just copies the pixels on the screen to the clipboard, and is not part of your application.
Basically you can hook to the ClipBoard events and then set the image copied to null if someone does it. So they can copy the image but it will be reset:
Have a look at this:
Clipboard event C#
Alternatively in a timer, check the content of the clip board and clear it as soon as it is set to a picture.
No, No way to do that. Even if you capture the Print Screen key in your application user might set focus to some other application and then do the Print screen(having your application on side etc.).
Only way would be to create a dummy application in background which captures all keystrokes using Keyboard Hooks and filters Print Screen, but that will happen for all applications not just yours. And moreover as George said user can use cellphone camera too!
I think Microsoft Rights Management System can help. Give it a try. Following is the link:
Microsoft Rights Management System
The only way I can think of is to use the native Windows API (SetWindowsHookEx) to catch all keystrokes and filter out the PrintScreen key. However this would involve creating a native (i.e. unmanaged) DLL to actually do the keystroke processing.