Start Menu and other directory junctions access denied

Here’s a screenshot of my c:\Users\UserName folder. Notice the “Start Menu” folder:

It is a directory junction to another folder, left behind for compatibility purposes. If I double click the folder though I get an access denied:

The actual target to which this points is accessible, but the junction itself isn’t. Every time I encounter this I think I must make a note of “why” this is so, but I forget. Today I intend to note it down once and for all. 

Remember from an earlier post: there are hard links and there are soft links. The former points to the data itself, and so only work for files. The latter points to the folder/ file containing the data. Soft links are an evolution of directory junctions (there are directory junctions and volume junctions). While directory junctions make use of something called reparse points and were introduced in Windows 2000, soft links were introduced in Vista and are baked into the kernel itself. Microsoft uses directory junctions – as we saw above – to redirect some of its special folders.

The important thing with both directory junctions and soft links is that they can have their own ACLs. So while a user might have full permissions to the target folder, the directory junction or soft link itself may not grant the user permissions and so the contents cannot be accessed via the directory junction or soft link. That’s what happening here too. 

First, from the command prompt note that this is a junction and that I can enter the directory junction but cannot see any files:

The files exist, however, as I can directly browse the target:

Compare the ACLs of the target and directory junction and we see the problem:

(I could have used the Explorer GUI here but I prefer icacls. In the GUI we have to dig down a bit more to see the relevant ACEs).

Notice a DENY entry for Everyone on the directory junction for listing the contents (RD). That’s why I can’t list the junction contents (in Explorer double clicking results in trying to list the contents, while in Command Prompt entering a junction and listing are two separate tasks – that’s why entering the junction worked, but listing the contents failed). 

What the above tells us is that only listing the junction contents is prohibited. If we know the names of some folders in there – as older software for whom this directory junction is present would know – we can go to those locations using the directory junction. Thus the following works:

There you go!