RE: Authentication question & problem

["Sheldon Malm" <smalm () ncircle com>]

There are pretty standard solutions out there to accomplish this with
one or more of the following solutions in place (I would recommend
combining some of these solutions if it's practical):
1. VPN between sites (pretty much as outlined below)
        - note that "their own authentication) mechanism" as stated
below by Tremaine does not necessarily mean user logon prompt (see point
#2 below).

2. Federated identity solutions (spanning authentication, authorization,
and probably federated provisioning as well)
        - SSO is a key component of making this work

3. Trusted strong authentication, if necessary
        - Trusted RSA ACE/Token realms have been in place for ages
        - PKI/Cert solutions have similar value

There is a tonne of information on the 'net about enabling Third Party
trust relationships with a simplified user experience.  The 3 outlined
above should give you a starting point to look over your options.  The
bottom line is, this is a business need that is well understood and has
lots of relatively mature options to address it. 


Sheldon Malm
Director
Security Research & Development
nCircle Network Security

Check out the VERT daily post
http://blog.ncircle.com/vert



-----Original Message-----
From: listbounce () securityfocus com [mailto:listbounce () securityfocus com]
On Behalf Of Tremaine Lea
Sent: Tuesday, April 22, 2008 3:31 PM
To: evilwon12 () yahoo com
Cc: security-basics () securityfocus com
Subject: Re: Authentication question & problem

It may be relatively straightforward, if approached differently.

Create a vpn tunnel between site B and site C.  Allow users from site B
to access the application on site C.  Allow users to remote in to site B
with credentials.

There should be no need for site C to be involved in your ldap
credentials.  The fact they are authenticated on a domain that site C
has chosen to trust should be sufficient.  If it's not sufficient, they
should be providing their own authentication mechanism.

It's a bit difficult to provide specific suggestions without more
information, but the above solution is definitely workable.

---
Tremaine Lea
Network Security Consultant
Intrepid ACL
"Paranoia for hire"



On 22-Apr-08, at 10:41 AM, evilwon12 () yahoo com wrote:
> Here is what my developers are wanting to do, and I cannot think of a 
> secure way to do this.
>
> Have a user (at home) authenticate against our LDAP through a company 
> portal/site and have that authentication information passed to an 
> external vendor, allowing the user at home to utilize the application 
> from home after being authenticated.
>
> So, it's user at site A, authenticating with site B, and the user at 
> site A using the application (after authentiation) at site C.
>
> Sorry for being long winded, but everything there screams MITM to me.

> I am probably missing something easy.