Hiding a Secret in Windows Registry - windows

I know registry is not a best place to hide something.
Right now I'm writing a Licensing software that require to save trial usage information like first install date on registry, etc.
What hive in Windows Registry that meet this criteria :
Not easily discovered by accident by the Users.
The value can be shared among Windows Users.
Didn't mess up Windows and Registry Cleaning Utility not consider this value as a garbage.
If can, it work without administrator privileges on Windows Vista and Windows 7
Edit : I have excluded items # 4 because it is not possible with item # 2, based on answers from David Heffernan

There are no shared locations in the registry that can be written to without admin rights. So your conditions 2 and 4 cannot both be fulfilled. You need to do this with a file I believe.
If you are prepared to drop condition 4 then you need to store it under HKLM so that it is shared. The obvious place is HKLM\Software\YourCompanyName\YourProductName. Naturally you would encrypt the data to avoid tampering. Once you have done that then you don't really care whether or not your users discover it.

What are you trying to defend against? It sounds like you're putting a lot of effort into "don't let people change their system clock to extend their trial" but none at all into "don't let people edit the Registry key to extend their trial" or "don't let people share Registry keys between machines to turn trials into full keys for free". I actually think those are far more likely. Any software that yelled at me for changing the clock on my own machine would get uninstalled in a hurry.
I recommend you don't try to do this yourself. There are licensing libraries you can use that have thought of the various ways people try to trick software. But if you must, because you want to try it, then take some time to distinguish what happens at install, which might require admin rights, from what happens while you're running and checking, which should not. An app that has to run elevated for no other reason than writing license info to HKLM once a minute would also be uninstalled in a heartbeat from my machine.
So at install, write something obscure/encrypted to a Registry key under HKLM. Make it something that's not super helpful to copy from machine to machine, while you're at it, by combining say a date, an email address, and some other information. At runtime, your code should look partly at the unchanging Registry entry or entries and partly at something else that can change easily, like a file under AppData, an HKCU key, or the current date, to decide whether it's ok for the app to run. (At runtime, if the HKLM key is not there or fails a checksum or whatever, refuse to run and ask for a reinstall. Reinstall can worry about whether the person is trying to get infinite free trials.) Focus on the main ways people try to trick licensing schemes and also on being a usable application. Insisting on elevating or preventing general use of the machine fails on the usability side.

You can, on install, change permissions of somewhere in HKLM so that all users have write access.
If you choose a place other than HKLM\SOFTWARE\Your Company Name\something than you're being foolish.

Related

Per Machine App Registration

I'm building an installer with WiX to install a program, per machine (not per user), and it gives them the option to register the program. Registration involves entering user name and organization (or accepting some defaults from Windows settings), and entering a valid registration key. When the registration key is validated, I write registry settings in the HKEY_LOCAL_MACHINE area with this information. Under Windows, when one runs the MSI, it prompts automatically for an admin password to be able to set registry values in HKEY_LOCAL_MACHINE. So far life is good...
I am including an option in the MSI to give the user the option to defer registration until a later point in time. However, if the user is a normal user and they are running the application, if I have a dialog in the app which prompts for name/org/product-key, Windows doesn't the app to write the information to HKEY_LOCAL_MACHINE. So a user cannot use the application itself, running as a normal user, to perform a registration per-machine as the MSI does after prompting for admin credentials.
My thought then was, for post-installation registration, to either (a) find a way from within the application to elevate privileges, with a prompt for admin credentials, allowing it to write HEKY_LOCAL_MACHINE (is this possible?), (b) include an option in the installer that, when run and the app is already installed and not registered, walks through the registration as it would during a normal install. It would then prompt for the admin credentials and life is good again. Alternatively, (c) create a separate MSI that just does registration, install this with the program, and call this MSI from the program when the user selects the "Register..." command in the program.
I've not seen either of these approaches done by any applications before, so I'm not sure either is a good approach. Other than that, however, I'm not sure how, post-installation, I can conveniently allow the user to do a per-machine app registration. Ideally, I'd like to be able to do it from a command within the app, but re-running the installation MSI would be minimally acceptable.
How is this normally done? Or are per-machine installations even normally accompanied by per-machine registrations?
Very good question - I have dealt with this issue many times myself. No ideal solutions, but several options (as you have already discovered).
Before answering, I want to point out that I have a strong aversion against doing too much registration and configuration in the setup itself. It is error prone, and much better done in the application itself for a plethora of reasons: Installer with Online Registration for Windows Application (recommended quick read - tidbits from real life experience).
Writing to HKCU
As you already know, one option is to keep the license key and registration in HKCU only. This is often acceptable unless you want to share a license key between many users on the box. The license key, if added to HKCU, will also generally roam with the user to other computers - which can be helpful or desirable.
Personally, this is the option I prefer: not registering anything in the setup, but writing to HKCU or the user-profile from the application (as explained in the link above as well). As stated, the only drawback is that you can't write a shared license key to HKLM so it applies to all users and not just a single user. This appears to be the core of the problem you are describing.
Writing to HKLM
Setup writes HKLM: Write the HKLM license key (and registration) during the setup to HKLM as Phil has described above using the default Windows Installer properties (just listing this as an option - which you already know about). This should work OK in my opinion - but your issue seemed to be to allow the "deferred registration".
Custom HKLM ACL permissioning: In order to write to HKLM from your non-elevated application, one way to do it is to use your setup to apply custom ACL permissions to the location in HKLM where you want to write the shared registry key from your application. Your application can then freely update this specific location in HKLM at any time without elevated rights. You simply add ACL write access for "Users".
WiX supports this, but I don't have a sample for you available, please check the WiX documentation for permissioning.
Using custom permissioning is generally frowned upon (and I agree it is not ideal design), but it allows any user to add a license key to HKLM without any elevation after the install (and also allows any users to delete it - which can be a problem).
See section 14 here for a quick description of why custom permissioning is not generally recommended: How do I avoid common design flaws in my WiX / MSI deployment solution?
In summary, I don't generally suggest setting custom permissions, but it will definitely work. I have done it myself when client requirements are such that this is the only thing they will accept. It will violate logo requirements for Windows applications, but it should be less serious than the security issues that result from option 3 below.
Run app as admin: If you don't want to apply ACL permissions, I believe you can prompt the user for admin rights for your application as described here (I believe this is what Phil referred to in his comment if I understand correctly):
How do I force my .NET application to run as administrator? (the legendary Hans Passant - one more answer).
This is most definitely not recommended (but we want to show people what is possible too). Your whole application will run with admin rights all the time, which is not a good idea at all.
Doing this will violate a key part of logo requirements for Windows applications and you will also open your application up to attack from malware.
Definitely try to make your users understand the consequences of this "easy fix". I would make sure to put all responsibility on the client if they go for this option - they must understand what they are doing.
Note that you should be able to use this manifest approach to launch a separate EXE with elevated rights to do only the registration. See next bullet point.
Elevate app on demand: I am not familiar with the technical details of elevating your application on demand whilst it is running - as you invoke a dialog or feature that needs HKLM access. Perhaps Phil knows a way to achieve this? I found some links though:
Elevating during runtime (from Code Project)
How to elevate privileges only when required? (good read)
Skimming the linked content above, it seems like you can launch a separate EXE with elevated rights to do your registration - a known option for you I assume.
Would love to hear back if this is something you decide to try. Could be useful for all of us.
Internet validation: Just throwing an option out there: what I often want to do is to put the whole registration license key validation online from within the application (never, ever try this from the setup, just so that is mentioned - a setup that tries to access the Internet might be the biggest deployment anti-pattern of all - at least for now).
I write the license key from the setup, and the validation of it takes place on application launch against a server on the Internet. Then there is no validation code in your application or your setup to crack.
You need an Internet "handshake" and you can repeat this process per user - allowing you to tightly control who is using your license key.
Nothing is ever easy, and proxy server issues could cause problems. Corporate deployment would also mean that such "online activation" is frowned upon. They want applications fully installed after deployment.
Separate registration MSI: I would prefer not to create a separate MSI just for the registration process as you mention in your question. This just seems like unnecessary complexity that can break easily. For one thing you get a dual source problem that must be permanently maintained. I would guess that this could become a classic support issue.
Re-run original MSI: I am honestly not sure if re-running your original setup to do the registration will launch it elevated or not. I think it will be elevated (should be, can't see any reason why it shouldn't - the MSI database stores a flag to determine if elevation is required "Word Count"), and then you should be able to add your registration details provided you access the registration dialog from the setups "modify" or "repair" modes.
This kind of registration is usually done using the standard Windows Installer properties so it just works.
If you have a verification key then it's typically associated (in the dialog) with the standard PIDKEY property which then after validation becomes the ProductId property.
https://msdn.microsoft.com/en-us/library/windows/desktop/aa370826(v=vs.85).aspx
Similarly the user name and company name are associated in the dialog with the USERNAME and COMPANYNAME properties.
After this, they're available through (Win32) MsiGetProductInfo () by asking for RegOwner etc:
https://msdn.microsoft.com/en-us/library/windows/desktop/aa370130(v=vs.85).aspx
or similar APIs (WMI does some of this).
So generally speaking you just set the properties from the dialogs and it all just works with no need for you to write them to the registry.

Deciding between GPO and straight registry editing NSIS

I'm writing an NSIS script to upgrade an appliance between versions. The versioning and setup have gotten away from us a bit, as we have many versions in the field, and currently no easy way to upgrade from one version to another. So the first task I have is to write something that they can run on field machines to do everything necessary to bring them to the latest version.
The appliance runs on windows 7. it has 3 users. In the repository for the project there are 4 .msc files that contain group policies to set the appropriate settings for each of these. (computer, non-administrator, admin, appliance)
Is this the right way to go? in trying to power through learning NSIS, it seems easier to write the registry keys directly to HKU /user/... rather than the extra layer of indirection from GPO, given that I'm not doing any sort of distributed system using active directory (which I know approximately nothing about), and just have 3 static users on one static physical machine.
So concise questions:
Which approach makes more sense for my application? GPO files, or direct ntuser.dat editing on the various users.
if GPO makes sense, how do I apply an msc file inside NSIS? double clicking the file works in windows, but then you have the mmc open. oogly. is there a clean way to do it with NSIS?
How does a GPO in the registry under HKCU translate to a system wide policy? it seems to me that what's written to the registry is missing the critical information of which users it applies to (if it applies to a user or group).
Thanks in advance
.msc files usually contain data used by MMC and not policy data, perhaps you mean .adm template files? I don't think you can really apply a .msc file programmatically.
Direct registry editing is probably OK if your application just reads them normally on the other end, otherwise you might need to call gpupdate.
If your policy is stored under Software\Policies then entries in HKLM applies to everyone and entries in HKCU/HKU applies to that user. A normal user cannot change their policy under HKCU because they don't have write access. There is not really a concept of groups when using these keys.

Windows registry key to prevent automatic drivers installation?

I'm looking for a simple method to prevent Windows Update from installing drivers automatically. Exactly these steps:
http://support.microsoft.com/kb/2500967
Is there any method to do these steps just by modifying registry keys? Or even by doing it with help of a simple bat file?
I've just found an answer. The key I was looking for is located here:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\DriverSearching]
"SearchOrderConfig"=dword:00000000
To add this values to our registry, we can use that command in our batch file:
REGEDIT /S NameOfOurRegFile.reg
I don't know of a registry key, but why not change the windows update to download, but not install. Then you can review the updates and use right-click-hide to hide the driver updates.
I like to see the driver updates because that lets me know that I might want to go to the vendor site to look at the real driver info and decide if I need it or not. I then only install the driver (from the vendors site) if there are changes I need.
And since I have hidden it in update, I don't get bothered again until a new driver comes out.
Just a thought (vs. hacking your registry.)
One other consideration. In some cases, a registry hack might have some side consequences that confound you late when you can't figure out why something you thought should work, doesn't. Most support options don't consider registry hacks when trying to figure out why something doesn't work...
I can't comment, so here are some things to consider.
What you want to do will possibly look very much like a virus that wants to prevent things from being fixed. So if you do find a way, I strongly encourage you to test it with a number of AV apps - and then register it with them so they don't add it later.
You do have an option to check the version of the drivers in use for given hardware items. Then, if your app sees a new driver, it can at least warn the user that a new driver was installed (and log that fact) and to roll the update back if they have problems.

Time limited trial and Windows Certification

If you want to implement a time limited trial for an application you would probably want to leave behind some flag (registry key, file etc) so a program couldn't just be re-installed.
Are there any schemes that allow you to do this while still passing the various Windows Certification programs?
Generally :-
Applications must correctly and fully
uninstall from the machine. This
includes removing files, registry
keys, GAC assemblies, database tables,
metabase settings, active directory
accounts, etc. Anything left on the
system after uninstall, including
system components installed by the
application, must be documented and
justified - Windows Server 2008 Software Logo Secification - 2.3 Uninstall Cleanly
You are taking the philosophy of only allowing installation if a flag is NOT there, which means you need to leave the flag there after uninstall. Also this fails when the user finds the flag and deletes it themself.
Better is if you turn it around and only allow the program to work if a flag IS there. This flag would be a registration key that has the date of expiry encrypted into it. When the program expires or is uninstalled, you delete the flag.
I implement this by making my users come to my site to register and get a free trial key. There are probably other ways, but I like this one because it also allows me to collect info about who is trying my program.
If your app is connected to the Internet, then you could store information on your own server about whether it has been installed before or not. However, this almost certainly needs to be designed in from the start with potential investment in hosting your own server to be available to check against.
I'm sure there must be plenty of cases where files are left behind after an uninstall that are perfectly acceptable. For example, I wouldn't expect all my documents to be deleted when I uninstalled Word.

When developing, do you turn off UAC in Vista?

I didn't upgrade to Vista until May or so and one of the things I've always heard developers I know in real life say is "first thing you should do is turn off that UAC crap"
Well, I've left it on this whole time for a few reasons. First, just as a failsafe in case I do something idiotic like have a momentary lapse of reason and run an attachment from an email, or in case I view a site which hits some unpatched exploit. Second, as a big of an experiment to see how good or bad it really is.
Finally, I figure that it enforces some better practices. I used to develop every website in Windows directly in inetpub\wwwroot (Visual Studio .NET 2003 more or less required this) but now I develop them elsewhere because the UAC clickfest is a nightmare. I figure this is Microsoft's way of saying "you should really be doing it this way".
By way of another analogy - if you wrote a web app which runs on XP and 2000 just fine but requires 50 different security features of Server 2003 to be turned off, the real solution might be instead to just fix the application such that it doesn't require the security features to be turned off.
But now I'm having to work with an app which is really really NOT designed to be developed outside of inetpub/wwwroot and so UAC is really a nuisance. It's beyond the scope of the project to rectify this. I want to stick to my guns and leave UAC on but I'm also worried about being so autopilot about clicking "Yes" or "Allow" three times every time I need to modify a file.
Am I just being hard headed? Do most developers on Vista leave the UAC on or off? And for the instance described above, is there a better/easier way?
I think it is necessary to leave UAC on on a test machine, so you can see what a real user would see using your app. However, I turn it off on my development machine since I find it distracting, and I trust myself enough to not need it.
(Hopefully your test machine != your dev machine right?)
All this being said, I support UAC, and I am not recommending anyone else turn it off, especially 'common users'.
I code in a standard user account, with UAC turned on.
No I do not close UAC.
Programming C# winform, and web with IIS. Database is progresql. No need to bother with UAC. Some program only require 1 authorization, not a big deal.
I keep UAC on. I find it useful to develop in an environment similar to my end user. That way if I write any code which is trying to read / write from restricted areas I will know about it quicker.
UAC is incredibly annoying at first when you get a new system. The problem is that when you first start out with a new install you have all kinds of programs to set up and settings to tweak. It seems like you see the UAC prompt every 5 minutes.
After a while, two things happen:
You're not setting up as much new stuff.
You've become a little more used to the prompt.
At this point UAC isn't so bad anymore. I have UAC on and I've only seen one or two prompts in the last couple weeks. That's right about perfect: if I see a prompt I wasn't expecting I know to make sure I really want to proceed.
I will argue that the 2nd effect kind of defeats the purpose. What they should do is have UAC disabled by default, but for the first month only. After the first month prompt you to turn UAC on, where the default option for someone who doesn't really read things is to turn it on. Then people aren't annoyed during their setup period, and it's easier to make an informed choice about what you want to do with UAC.
I leave it on
I leave it on, but have it set to automatically elevate privileges when necessary. It's a fine distinction, but a distinction nonetheless.
Services like Microsoft SQL Server runs with administrator privileges. Visual Studio on the other hand does not. Nor do most developer-tools.
I make heavy use of virtual machines to 1) make sure my development environment is safe at all times, and 2) to test out software with the potential of leaving my machine FUBAR. And 3) to limit down-time, restoring my development environment, "in case I do something idiotic like have a momentary lapse of reason and run an attachment from an email" :)
I have been using Windows 2008 in my workstation following the advices on http://www.win2008workstation.com/wordpress/ and it has worked great for me. I don't remember turning off UAC, but certainly I haven't suffered it, so I guess it's turned off.
As others have said, you do need to have test [virtual] machines that are configured as close as possible to the ones your users will have so you won't have any surprises deploying your app.
I think whether you do this or not should depend on the target audience for your application, although I can completely understand people disabling it.
If all your users run Vista with UAC disabled then I think you can get away with turning it off, but this probably isn't realistic--or advisable. At the other end of the spectrum, our applications are used by a vast number of people with every conceivable version and configuration of Windows from Win2k onwards, and obviously including Vista and Server 2008. Since we're an ISV with no control over our users' environments, or over policies governing their privileges and administration, I always leave UAC enabled--even though it annoys me beyond all reason at times--because then I know about any possible problems it might cause for people using our applications sooner rather than later.
Disclaimer: most of my actual coding time is spent on Windows XP, although I have a Vista 64-bit test machine under my desk which I use on a daily basis for testing. Generally I'll use this box around 20 - 30% of the time.
Developing or not developing - was the first thing I did after installing vista. Just seemed an annoying nuisance at best.
Instead of running antivirus to suck away my CPU cycles (I need as many as I can with RDPs and VMs running all the time). I just leave UAC on as a safeguard to double check and make sure only certain things run. It does more than that though, it also restricts programs access to sensitive areas, so a program basically can't trash your system without you allowing it through UAC. I have not had a problem yet and my system runs only what I need it to run, quickly and smoothly.
It's too annoying for me, it gets turned off as soon as I install Vista.
I turn it off as soon as I install the OS. Security by endless modal dialogs is no security at all. Normal users just get used to clicking even more 'OK' buttons after a couple of weeks or so.
EDIT: Wow, down-voted huh? Must be some Microsoft employees around here...Of course it should remain on on a test machine, probably should have mentioned that.
I turn it off on computers that I am using.
When testing, I test in the target environment, which means I may have UAC on or off.
I see no benefit to developing with it on.
I find it extremely annoying and turn it off at all times, I trust myself enough to not have to have fail safes in place. If I screw up and run some dodgy application that's my bad and I'll live with the consequences. Meanwhile I'm not spending 5 minutes of my day clicking though some damn annoying popups.
I have it off, but that's because I trust myself entirely too much. Its funny though, it seems to make the average user (I live in Jourdanton TX, we have a lot of "average users" here in the middle of nowhere) afraid of the control panel, because it causes all these weird prompts to come up and wants their password every 5 minutes if they start to poke around.
That said, I think it depends on your level of expertise with the system. On your dev machine, yes, definitely turn the darn thing off. I haven't gone a day this week without needing to install or update some piece of software, and I don't like having to elevate myself to admin status to have to do that.
What I would really like is the ability to have it elevate for a period of time, or say automatically turn itself back on when I log off, so that I could do an entire session's worth of installing stuff without being bothered, and then be secure again when I was done and (inevitably) had to restart the machine as seems to be common practice with windows installers now.
And all that ranting aside, I think for your test machine, it should definitely be on. Not because I necessarily agree with the feature (any more than I agree that the Administrator account should be disabled permananty, I love that account way too much) but because the User is very likely to have it turned on, and you need to see your program through their eyes. This is especially true if your program is going to require elevation, say to change a setting or modify a certain directory, so that you can prompt your users to accept the UAC warning in your program, which adds an extra layer of comfort to the user I think.
Oh, and as for the one program, let me harp on you just slightly. Shouldn't the program have a define somewhere in the main header files that tells it where its "working directory" is? If this is already the case, then why is it so hard to change that working directory to somewhere else? If its not the case, shame on you, and you should go fix that. ^_^ That would have saved you a lot of trouble.
-Nicholas
I'm running into issues where our build scripts do things like manipulate registry entries or add things to the GAC. We're trying to get away from this stuff but until we do it's there and requires privilege escalation. So the build scripts get run from an Administrator command window. The problem comes in when I open Visual Studio 2008 and try to build part of the application - I can't as a normal user because the output files can't be overwritten because the build in the Admin console produced the same files at a higher privilege level. It's causing me a lot of frustration and I'm thinking the best way is to turn UAC off for now but I'm very reluctant to do so.
Because I've got post-build scripts to copy executables into the Program Files directory for testing I run Visual Studio with elevated privileges.
One tip I've found that makes life easier, is that to quickly start a command prompt with elevated privileges you can:
press Window Key
type "cmd"
Press Ctrl+Shift+Enter
Left cursor key (with right pinky) to move to "Continue" button on UAC dialog
Enter
I always keep one open for launching my IDE and running build scripts.
The only downside I've found is that elevated windows don't interact with some of my window tweaking software like KatMouse and Switcher.
No, but I do change some settings:
Do not prompt for elevation if not in the administrators group.
Evelvate automatically if you are the [machine]\administrator
I do not put myself in the administrators group.
Juts a plain old user, with no elevation prompts.
Use Run As if developing/debugging web apps with development server
I code with UAC off. I found annoying to see all those popups when i open visual studio or star uml, or just want to change a setting in my machine. I have always installed a good internet security suite that keeped me "virus free" on my machine for long years and i don't see the point to have always an "are you sure" prompt on every task i do. I agree with Ed because everyone click ok.
Exemple : install a firewall to some member of your family. When they will be prompted if app XYZ can connect to the internet, they will click yes. They will not make the distinction between a good app and a spyware/virus. It's the same thing with UAC.
I leave UAC on, but have VS set to always run as admin. The only real reason why I do that though is that I mostly work on software that requires admin permissions to run anyway. (And yes, I know that should be the minority, but my app happens to be one of those -- it's a soft-realtime hardware controller.)
For general purpose apps, you must at least test with UAC enabled; while you could do that on a separate machine, it's easier to test on your dev machine. And the prompt isn't that much of an imposition, especially if you disable the "secure desktop" option (which reacts very slowly with most graphics cards when enabled).
If you stay on Vista, turn off UAC and rely on Microsoft Security Essentials' real-time monitor to intercept anything that wants to alter your system. Or, upgrade to Win7, where you can leave UAC on and control the levels at which you want UAC to notify and interrupt the execution.
EDIT: It's very easy to exploit a Windows computer anyway, so what's the sense in having UAC turned on, if it really doesn't guarantee protection?

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