How to Make List Items Visible to Anonymous Users (in Search)

I had a funny little issue with showing list items from a custom list (with a custom view form) to anonymous users on a publishing site.

My good colleague Bernd Rickenberg insisted that I blogged the resolution since he had found quite a few post detailing the problem but no viable solutions 😉

The Issue

You want to show a custom list to anonymous users. In our setting it was through search, your use case is likely different, but the issue remains the same with or without search.

Quite simply forms (List forms) are generally not accessible to anonymous users when you have the lockdown feature enabled (ViewFormPagesLockdown). It is a critical feature to have enabled otherwise you expose way too much information to SharePoint savvy users. Many of the solutions to this issue suggest turning it off.

It is fairly simple to test if you have this problem. Start Firefox, assuming that you have not enabled the NTLM auto login setting, and hit the …/DispForm.aspx page for a specific item. If you receive the login prompt as anonymous in Firefox and sail through when logged in this blog is for you.

If the ordinary publishing pages are also not viewable then this blog is not for you.

Note: Never use IE to test for anonymous access or not, I can’t count the number of times it has tricked consultants into thinking it works because they are tricked by the auto login feature while on the corporate network.

The Resolution

Is fairly simple.

The basics for search is that the list must be made searchable (it is by default) in the list settings, anonymous users must have access rights to the site and the lockdown feature should(!) be enabled.

What the lockdown feature does is that it changes the anonymous permission mask at the root site (which is inherited by all by default). The mask is basically the permission level assigned to all anonymous users and is similar to the normal permission sets – but is not editable in the UI.

The “View Application Pages” permission level is removed, see the image below on where to find it (for non-anonymous users):

Permission level settings page

Permission level settings page – not available for anonymous users

The best option, security wise, is to break the permission inheritance for your particular list and then add the “View Application Pages” permission to the anonymous users. Do not do that at the web level as you do not want to expose e.g. All site content etc.)

The Script

You need to run the following the PowerShell commands on one of your servers (replace url and list name):

$web = get-spweb "http://yoursiteurl/subweb/subsubweb" 
$list = $web.Lists["ListName"]
$list.AnonymousPermMask = $list.AnonymousPermMask -bor ([int][Microsoft.SharePoint.SPBasePermissions]::ViewFormPages) #binary or adding the permissions

(Note: Do be careful if copying directly from this page to PowerShell – you need to re-type the quotes as WordPress mangles them)