I know that this is a topic that has been discussed many times and people always claim: Wix bootstrappers should not require to be run elevated. Let me explain our requirement and hopefully anybody can suggest a solution that will work on all systems.
Our installed software is a Windows Service which runs elevated. The service has various settings which are stored in a database that can only be accessed by administrators. The installer also allows the configuration of those settings which is done as part of the elevated phase of the installer. And here is the problem: We cannot load the current settings from the database within the unelevated phase of the bootstrapper.
The easiest solution would be to run the whole boostrapper elevated but it seems that Wix intensively tries to prevent elevated bootstrappers by design. All discussions in this area result in wierd solutions where external tools are used afterwards to embed an application manifest after the Wix compilation.
Yes in theory we could rework the whole database credentials in order to allow the installer read access but I would like to prevent this due to security reasons. We could also keep a copy of the settings for the installer on a readable location (e.g. registry) but this is also not nice to maintain.
Is there some clean Wix-built-in mechanism to load those settings or elevate the bootstrapper from the beginning using an application manifest? We are aware that elevated bootstrappers are "not nice" to the user but our software addresses service operators that anyhow must have administrator privileges in order to operate our software.
Update #1: We already have a custom WPF-GUI as bootstrapper application utilizing the Microsoft.Tools.WindowsInstallerXml.Bootstrapper.BootstrapperApplication class provided by Wix.
If it's not necessary for the UI itself to be elevated you can force the install engine to elevate so all the bootstrapper packages will be installed\executed in an elevated mode.
To elevate the engine use the Elevate method of the Engine (the Elevate gets a 'IntPtr hwndParent' parameter - I've used the IntPtr of the window and it worked great).
(Calling the Elevate method will show\pop the UAC elevation screen)
Just keep in mind that the Elevate method is not a blocking operation and from I remember it always returns true. The only way (that I've found) to determine if the elevation actually succeeded is to register to the bootstrapper's Error event and check if the error type is ErrorType.Elevate.
Keep in mind that in this solution the UI itself will remain un-elevated.
Related
I'm currently planning an installation and update scenario, using MSIs created using Wix.
Initial installation will include third-party drivers as merge modules, which will require elevated permissions.
We want to automate software updates as much as possible, so will make updated MSI packages available on a regular basis. These will be downloaded in the background and installed the next time the user opens the application. We will implement processes to ensure changes to the driver modules will not be included in automatic updates.
Will Windows Installer execute these merge modules if they are not changed? What impact will this have on the overall installer? Would I be better off creating a separate MSI for these drivers, to isolate them completely from the core application package?
Here's some background to help clear things up. Merge modules are not "executed". In fact, once you build an installer they don't exist anymore. A merge module is merely a database containing MSI table data that gets merged into your MSI at build time. Think of it as an encapsulation of a collection of components and related metadata. It's like a C/C++ .LIB file that is statically linked inside an EXE.
So if you have components ( from an MSI or from an MSM ) that require elevated permissions to install then the final MSI requires elevated permissions to intall.
I've done this autoupdate process in the past. You want that process to have elevated rights and after it downloads the MSI "advertise" it as a managed per-machine (what I call "blessed" MSI ). This is done using the msiexec /jm foo.msi command. Then signal a user side process to install the MSI. If authored correctly the MSI will auto elevate without ever exposing admin rights to the user.
I have a small application that is designed to run under currently logged on, non-administrative workstation user. Application can be installed manually but I also made sure that it is compatible with Group Policy Objects (GPO) software distribution method - I have .msi files for old systems (XP/Vista): separate files for per machine and per user installations as well as .msi file that takes advantage of Windows 7 (and newer) compatibility with WIX Allusers=2 option to allow automatic registry and folder path redirection depending on the installation context.
All is good there, but I am just wondering, is there anything special I need to do to make my installer suitable for installation using Microsoft System Center Configuration Manager? I do not really have resources to just test such a scenario myself and would like to find out about theoretical requirements for installer files for SCCM.
At my day job I'm the Deployment Architect for a Fortune 50 company with an SCCM 2007 environment ( currently migrating to SCCM 2012 ) that has over 300,000 clients. Here's a few tips.
1) We don't do Per-User installs. They are impossible to manage and report on. If an installer must have Per-User resources and we can't get the application (typically vendor provided) we do this using an Active Setup technique where the first time each user logs on the MSI does a repair and populates the Per-User resources. Just realize you'll never get it off... it's essentially forever.
2) SCCM can handle non MSI deployment types but well written MSI's work the best.
3) Use snapshotted VM's to test your install in the SYSTEM context. (PSExec is your friend)
4) Test your install, uninstall, reinstall, upgrade, repair, change. Make sure everything is bulletproof.
5) Don't wrap up prereqs into a setup.exe bootstrapper. Decompose it and allow SCCM to package each of these items. You can then use package chains, task sequences or application model to allow SCCM to manage the chaining. You get better status, reporting and efficient use of the system.
Just a couple of thoughts if I remember these things correctly - the MSI should be capable of silent install, and among other things that means no custom actions exclusively in the UI sequence, because they will not be run at deployment time because you will probably suppress the UI. The execute sequence shouldn't have custom actions that might explicitly display messageboxes requiring acknowledgement unless they are based on calls to the Win32 MsiProcessMessage() API or equivalent.
I have built a Windows Installer package using WiX 3.6 that embeds a custom managed (C#) action.
At this stage, the installation requires that
The installer be run using a specific local administrator account (in this case, the SharePoint installer account, which is a local administrator)
User Account Control be disabled
There really isn't a way I can bypass requirement #1, because the managed action can only perform certain steps if it runs in the context of the SharePoint installer account.
I would like to remove requirement #2 and let the installer properly run even if UAC is enabled.
I've researched the issue quite extensively but still can't get it to work. I have set InstallScope="perMachine" in my package, which seems to properly prompt for UAC elevation, but the installer still fails with the infamous 2869 error.
The main problem is that my custom action is configured with Impersonate="yes" because it has to run in the context of the current user, not the local administrator account. When I search online, almost all "fixes" point to Impersonate="no" in the custom action, but that's not an option for me.
My question therefore is: is there a way to run a custom managed action with the identity of the current user without requiring UAC to be completely disabled?
When you use Impersonate="yes" your Custom action runs without administrative privileges with the credentials of the currently logged user.
When Impersonate="no" your Custom action is run in System context. When running in system context, the custom action has full access to the system.
From WiX CustomAction element documentation, Impersonate attribute:
This attribute specifies whether the Windows Installer, which executes as LocalSystem, should impersonate the user context of the installing user when executing this custom action. Typically the value should be 'yes', except when the custom action needs elevated privileges to apply changes to the machine.
Where are you referencing the custom action?
Having the .msi running with elevated privileges might not be enough.
To be sure that your custom action works with elevated privileges you also have to use a deferred custom action and reference it in the InstallExecuteSequence. This might not solve your problems, but the articles linked at the bottom goes in detail in explaining the UAC logics during an msi installation.
Basically, not everything the installer does carries the privileges with it, an you have to be sure to run the custom action when the installer is using the elevated privileges.
Source: http://blogs.msdn.com/b/rflaming/archive/2006/09/30/uac-in-msi-notes-when-general-custom-action-mitigation-fails.aspx
I hope you find this information useful, I might be of more assistance if you share your custom action code.
I am working on a project that has been using 2 VD projects to distribute admin and user versions of installations, and now I need to switch to WiX. It was a bit painful experience with lack of documentation and all, but I managed to make something of it.
However, there is still one problem: I want to make only one .msi which will allow user to choose whether he wants to install as admin or as user. If he chose user, I don't want to ask him for elevation (as he doesn't need it), also if he chose admin, I don't want the installation to crash but to ask for privileges.
My current solution crashes in admin mode if I set InstallPrivileges to limited because the user doesn't have the permission to install, and it prompts for elevation in user mode if I set it to elevated.
My opinion is that there is no way to fix this because of compatibility with MSI, but perhaps there is some way to change privileges from elevated to limited in install time that I'm missing.
In conclusion, I want to know these things:
Is it possible to change privileges at install time
If there is no way to do so, what is the best workaround for this problem (exporting 2 .msi files or something)
One solution is to build two separate installers and then launch them via a custom WiX bootstrapper (aka Burn). The bootstrapper would be in charge of displaying the UI and launching the appropriate .msi.
Or you could separate the "admin" features into a separate .msi and then use a custom bootstrapper to install both .msis if the user selects an admin install.
I implemented an installer for our product. Installer needs administrator privileges, so I used setup bootstrapper with a manifest file (as recommended here) to get these privileges on a Windows machines with UAC enabled. Installation and uninstall goes fine - the user is asked for permission and the installer does what it needs to do.
But if you run Control panel → Programs and Features and select "Change"* for installed program, an error occurs (custom, from installer LaunchConditions), telling that the installer needs administrative privileges. And I can't find any way to ask for permission in a such case - Windows simply runs the MSI file and doesn't know anything about required permissions.
Even more strange is the repair functionality - it asks for permission, but then fails to do some actions that were allowed during installation, using SetupBootstrapper.
I found a similar problem here:
But the proposed solutions are unacceptable in our case.
The only workaround for the change functionality now is to always use SetupBootstrapper and do not use the Programs and Features menu, but that is not very user-friendly and forces the user to keep the installer on his/her hard drive.
Has anybody better advise?
PS: I use WiX for creating the installer, so it would be great to hear about WiX solutions, but I'm pretty sure that it doesn't depend on the installer creation language, but only on MSI specifics.
What actions are failing? If they are actions that you added to the installation, make sure that such actions are defined with Impersonate="no" and Execute="deferred" (or "commit" or "rollback") and that they are sequenced somewhere between InstallInitialize and InstallFinalize.