DavidXanatos
commented
4 years ago From 1809 to 1903 MSFT changed something around the "msiServer" service. On 1809 when trying to install a msi file inside a sandbox, Start.exe starts an sandbox internal instance of that service. On 1903 it does not even try to start the msiServer.
You can use a tool like TaskExplorer with enabled ETW Monitoring and use the "hold" option (snow flake icon on toolbar) to view all processes running as well as started and terminated.
Anyhow, the fact that Start.exe does not even try to start "C:\Windows\system32\msiexec.exe /V", tells me that most likely a trigger for the service to be started has changed, or is missing entirely, and we need to find an other one.
The way it seams to be supposed to work is that the SbieSvc.exe, from RunHandler2, invokes: "C:\Program Files\Sandboxie\Start.exe" /box:-1688 /env:00000000_SBIE_DEVICE_MAP="\Sessions\0\DosDevices\00000000-0004f782" /env:00000000_SBIE_SERVICE_NAME="MSIServer" /hide_window C:\Windows\system32\msiexec.exe /V btw 1688 is the pid of your SandboxieDcomLauchner.exe this does its thing and causes SbieSvc.exe run "C:\Program Files\Sandboxie\Start.exe" /env:00000000_SBIE_CURRENT_DIRECTORY="C:\Windows\system32" /env:=Refresh C:\Windows\system32\msiexec.exe /V and this is the process that in turn starts "C:\Windows\system32\msiexec.exe /V"
What fails is the trigger for the first command.
If I run the first command with the right pid and dosdevice it triggers the second one and causes the service to start briefly. Unfortunately not long enough to be usefull...
A good point to start looking is Sandboxie\core\dll\scm.c as it's responsible for services and contains stuff related to MSIServer.
EDIT: A thing I find strange is that when you start services.msc from inside a sandbox you can start services and they start outside the sand box, ok, you cant stop them and i guess not access them, but still its an unexpected behavior. Services Sbie intents to be run inside the sandbox fail to start this way, these are trustedinstaller, cryptsvc, msiserver, bits, wuauserv, that is also unexpected if we could start msiserver this way any than try to install a msi file we could validate that only a trigger is missing and that the rest isn't broken.
DavidBerdik
ecoeficiente
deflock
fakuivan
It appears that the "Windows Installer Service could not be accessed" error is still present in this release.
The good news is that now, we can fix it ourselves! That is, we can fix it ourselves if we understand the code. I've been reading through the code trying to get a sense of how it works, but have admittedly made little to no progress. Do you have any idea how to fix this? Or at least some pointers as to where I should be looking?
Reproducing the issue is very simple: try to run an MSI installer inside a sandbox, and you will get this error.