Changing 403 to a 302 response based in incoming User-Agent?

We have uncovered an unexpected 'feature' in Microsoft SharePoint that's causing us some problems. Specifically, if SharePoint detects a non-browser client attempting to access a secured page on a site using Forms Authentication, it will return a 403 response rather than the normal 302 redirection to the forms logon page.

 

 

The problem is, SharePoint's definition of a non-browser client is anything without 'Mozilla' in the User-Agent string. And unfortunately, many of the mobile browsers on the market don't send 'Mozilla' anywhere in their UA string. I am wondering if this is something I can take care of in LTM. If the server is attempting to send a 403 response to the client and if the client's UA string does not contain 'Mozilla', I would like to modify that response to be a 302 redirection to the logon page (/_layouts/login.aspx?ReturnUrl=.

 

 

Is there a way I can tie a request coming in that doesn't have Mozilla as the user agent and wait for the response to see if it's a 403 and then do the redirect using an iRule?

 

 

DB.