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I believe the default permissions for a volume grant users the ability to create folders, so they should be able to create a folder in C: called Temp and put fi

I believe the default permissions for a volume grant users the ability to create folders, so they should be able to create a folder in C: called Temp and put files into it. It’s also possible that when Skype’s updater creates the folder it has different ACLs.

Someone1234 9y ago
> I believe the default permissions for a volume grant users the ability to create folders, so they should be able to create a folder in C: called Temp and put files into it. That's inaccurate. UAC makes it appear like you can, if you try to do this as an unprivileged user on a default install it will fail. Plus even if you could create C:\Temp, you'd need to add it to the system-scoped environmental variable PATH for it to be searched for libraries. If you could do that you've already effectively escalated without this. This Skype issue exists because they're running a SYSTEM level process from a directory a normal user owns.
Amezarak 9y ago
%SYSTEMROOT% is C:\Windows, not C:\. I too cannot access C:\Windows\Temp at all without escalating permissions. Neither can I write to anything in C:\Windows as described in the original source without escalated permissions. I'm a little puzzled about what would stop someone with the same permissions from doing exactly the same thing with the fully qualified name.
- enzanki_ars 9y ago
  I need to test this later as I only have access to an unprivileged account at the moment, but based on comments online (https://stackoverflow.com/a/11917816 https://stackoverflow.com/a/11917816), C:\Windows\Temp (%systemroot%\Temp redirects here, and is the folder Skype accesses from, is write only for unprivileged users (FILE_ADD_FILE). Preliminary testing shows that I was able to write there with out any problem. No way for me to read it at the moment though... Edit: As noted by another user here, yes, it is writeable. https://news.ycombinator.com/item?id=16367722 https://news.ycombinator.com/item?id=16367722
- deleted 9y ago
  [deleted]
- taspeotis 9y ago
  Oops, my mistake. Thanks for the correction.

Someone1234 9y ago

> I believe the default permissions for a volume grant users the ability to create folders, so they should be able to create a folder in C: called Temp and put files into it. That's inaccurate. UAC makes it appear like you can, if you try to do this as an unprivileged user on a default install it will fail. Plus even if you could create C:\Temp, you'd need to add it to the system-scoped environmental variable PATH for it to be searched for libraries. If you could do that you've already effectively escalated without this. This Skype issue exists because they're running a SYSTEM level process from a directory a normal user owns.

Amezarak 9y ago

%SYSTEMROOT% is C:\Windows, not C:\. I too cannot access C:\Windows\Temp at all without escalating permissions. Neither can I write to anything in C:\Windows as described in the original source without escalated permissions. I'm a little puzzled about what would stop someone with the same permissions from doing exactly the same thing with the fully qualified name.

enzanki_ars 9y ago
I need to test this later as I only have access to an unprivileged account at the moment, but based on comments online (https://stackoverflow.com/a/11917816 https://stackoverflow.com/a/11917816), C:\Windows\Temp (%systemroot%\Temp redirects here, and is the folder Skype accesses from, is write only for unprivileged users (FILE_ADD_FILE). Preliminary testing shows that I was able to write there with out any problem. No way for me to read it at the moment though... Edit: As noted by another user here, yes, it is writeable. https://news.ycombinator.com/item?id=16367722 https://news.ycombinator.com/item?id=16367722
deleted 9y ago
[deleted]
taspeotis 9y ago
Oops, my mistake. Thanks for the correction.