Kategoriarkiv: Security Trimming

SharePoint 2010 Security Breach: Export to Excel Ignores Security Trimming

I’m currently working on a project where there are lists where permissions are broken and set on the list item level. Basically there are different groups of users, and some should see all items, and some should only be able to view a fiew of them. Now, all of these users have contribute, and can use the ‘Export to Excel’ function, which is very important to them. Now here is the issue I found out just a few days ago. Export to Excel ignores security trimming!

So what does this actually mean? Let me illustrate using a fictional example:

I have a list called Accounts, where I store important information about clients and the business I have with them. Some accounts are secret, so I break the permission inheritance on them. Let’s say I have three accounts, A, B and C. Account A is secret, and I’m the only one who has permissions to view it. Now, I have a group of colleagues, who also have access to the Accounts list, and can contribute to it. But when they visit the list, they can’t see Account A, since I have removed their permissions from it. Now what happens when one of my colleagues use the Export to Excel function? You would think that the generated Excel file would only contain accounts B and C. But no! The export function ignores the permissions of the user and only checks if the user has permissions to acces the function itself. The result is the user being able to see account A as well, giving it access to information that should be hidden.

In my opinion, this has to be regarded as a bug, because if this is by design, it’s poor design indeed.

EDIT:
I tested this in SharePoint 2013, and the bug seems to be fixed. Will try and see if there is a hotfix or CU fixing this issue for SP 2010.

EDIT2:
After installing the July 2014 CU for SharePoint Server 2010, I can confirm that the bug is not fixed. It has to have been fixed for SP 2013 only.