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When running as Administrator, Terminal should always start built-in Windows apps in C:\Windows\System32 #7062
Description
Description of the new feature/enhancement
When you open Command Prompt or PowerShell from the Start Menu, Start --> Run (Windows-R), or the set of options you get by right-clicking the Start button (Windows-X), the starting current directory for the shell can vary:
- When the shell is run as an ordinary user (or a administrator without elevation to admin privilege/token), the starting directory is
C:\Users\me, or whatever the user's home location is. - When the shell is run as an administrator, the starting directory is always
C:\Windows\System32.
This is also true for non-shell command-line apps that are launched this way, like C:\Windows\System32\choice.exe - EDIT: as long as they come with Windows.
However, when command-line apps are launched from Terminal using a Terminal profile, the starting directory is always static:
- If
startingDirectoryis set to non-null and non-empty (in settings.json or defaults.json): that directory - If
startingDirectoryis set to an empty string:C:\Users\me - Otherwise - if
startingDirectoryis set to null or not set:C:\Windows\System32
What I'd like is for Terminal to emulate part of the built-in behavior of the Windows system described above:
If Terminal is elevated, then the starting directory for any new Terminal tab or pane should always be the system directory C:\Windows\System32.
EDIT: If Terminal is elevated, then the starting directory for any new Terminal tab or pane opening a built-in Windows system file should always be the system directory C:\Windows\System32.
This reduces the chance of damage when you accidentally run (or are maliciously tricked into running) a program from your home location or other unprivileged folder that has the same name as a program in C:\Windows\System32.
Activity
KalleOlaviNiemitalo commentedon Jul 25, 2020
You could set the
NoDefaultCurrentDirectoryInExePathenvironment variable, documented at NeedCurrentDirectoryForExePathW function.DHowett commentedon Jul 25, 2020
You know, I think the behavior you're seeing is actually a side effect of how the shell spawns elevated applications. When you run an application as an administrator from its installation directory using the context menu, it runs in its installation directory. When you run it from a shortcut designated to run as an admin but with a specified startup directory, it actually does open in that startup directory.
This sounds like an implementation detail wearing a white coat with "Dr. Security" embroidered on it.
metathinker commentedon Jul 28, 2020
It's a bit more complex than that... I studied the implementation of starting an application elevated. When Explorer or some other unelevated process running the shell API impl. needs to start an elevated process, it (actually the "Application Information"/AppInfo NT service, the trustworthy worker process that starts the elevated process for Explorer) special-cases applications in C:\Windows and most other directories in that tree, which for our purposes includes Command Prompt and Windows PowerShell. For those applications, the start-in folder specified by the shortcut is ignored in favor of C:\Windows\System32. The ignorance is deliberate - there's even a comment to call out that the specified start-in folder path is being thrown away to discourage attacks by using the program loader to load untrustworthy DLLs.
Windows Terminal doesn't follow the same path when launching an elevated cmd.exe or powershell.exe because it is already elevated - it doesn't need to use the special-case code described above in order to launch cmd.exe. So the feature request is that it should do the same thing, but perhaps that is not easy to implement as you have to mirror at least some of the logic to answer the question "is this program in a known, safe C:\Windows path?"
[-]When running as Administrator, Terminal should always start apps in C:\Windows\System32[/-][+]When running as Administrator, Terminal should always start built-in Windows apps in C:\Windows\System32[/+]miniksa commentedon Jul 19, 2021
I've contacted one of our friends on the security research team. I gave him the rundown of what we discussed in our triage meeting about this particular issue today and he provided several counter points that we should consider. There wasn't a definitive conclusion beyond the fact that he will raise this with the rest of his team later this week to get more security minds thinking about it and advise us on a recommendation going forward.
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