Allow user control over installs

since 0.9.8.11

Purpose

Show registry keys (1)

HKLM\Software\Policies\Microsoft\Windows\Installer\EnableUserControl

This per-machine REG_DWORD value controls which public Windows Installer properties a non-administrative user can influence during a managed installation running with elevated privileges.

When EnableUserControl is set to 1, Windows Installer passes all public properties to the elevated server-side portion of the installation. This allows the user to modify properties that would otherwise not be accepted from the non-elevated client context. Depending on the package, these properties can affect installation options or the destination directory.

When the value is 0 or absent, Windows Installer accepts only restricted public properties and any additional properties explicitly designated as secure by the package author. Other public properties supplied by a non-administrative user are ignored.

Notes

Security

A value of 1 weakens the boundary between the non-elevated user interface and the elevated server-side portion of a managed installation. It allows a non-administrative user to influence public properties that Windows Installer would normally restrict for security reasons.

The specific consequences depend on the MSI package and how it uses those properties. A package with an unsafe design may allow user-controlled properties to affect privileged installation operations or may complete when Windows Installer would otherwise stop it because a protected option was exposed to the user.

This setting does not independently grant administrative privileges or cause arbitrary installations to run elevated. It has an effect only when a managed installation is already running in a privileged context and the package uses public properties that the user can influence.

Possible side effects

When the setting is disabled or not configured, an incorrectly designed package can be stopped if it permits a non-administrative user to change a protected installation option. Windows Installer displays an error in that situation. Setting the value to 1 can allow such a package to complete by removing that restriction.

Notes

The policy has the same effect as the Windows Installer EnableUserControl property. It applies to public MSI properties; it does not convert private properties into public properties or otherwise expose them through this policy.