Re: Application Flow / security issues

Thanks for the kind words. I'm Ryan's better half in the .NET LDAP world.
:) I also do this "distributed authentication in web apps" stuff quite a
bit.

So basically, if you can ACL the file shares on the machines that you need
to access such that the machine account for the web server has the
appropriate file system rights to do what you want to do (read a file or
whatever), then it should work to use Network Service as an app pool
identity. You won't need a special service account.

If the use case of the app is basically to have a user log in and then loop
back to their own workstation to access a file share there, then using the
trusted subsystem design in this case basically just means that you would
ACL the share to grant access to the machine account instead of granting
access to that user's own account.

Obviously, you would want to test that.

I'm not sure how your admins would enforce a limit on how many machines a
particular service account could access, but I don't want to have anything
to do with your organization's internal politics around the management of
their directory, so I'll steer clear of that one.

You might also consider using the website to upload the file. That might be
even easier than looping back around via a file share. :)

I hope that helps,

Joe K.

--
Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services Programming"
http://www.directoryprogramming.net
--
"Justin Rich" <jrich523@xxxxxxxxxxxxxx> wrote in message
news:u4Yl1iSBIHA.4200@xxxxxxxxxxxxxxxxxxxxxxx
need is a touchy word :)

So are you saying that if I add the computer account of my server to the
admin group of my clients I can leave the app pool under the default
context of network service?


I just checked with corp. and if I want to do delegation I have to ask
much higher up than I thought.. and I doubt id even get a hello back from
them let alone permission to do that..
as far as a service account apparently im limited to 60 machines it can
access, and my count is over 400..

so, if I understand you correctly, I'll use the machine account, I think I
can pull that one off.. that or im stuck using my creds, which would
suck..

just so you have a picture of whats going on im having the techs run a
monitor calibration on the workstations and then log in to my website. the
web app pulls the calibration info (text file) from the workstation and
some other stuff as well as some manually entered info and dumps it in to
a database so that we can monitor the degradation of monitor quality.

This whole time I was looking at your name and wondering where I
recognized it from and when I finally read your sig I realized where, the
book. great publication! I've received help from Ryan in the past with
some AD stuff and I must say you both seem to know your stuff extremely
well!

Thanks
Justin


"Joe Kaplan" <joseph.e.kaplan@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:uaN7E4RBIHA.5752@xxxxxxxxxxxxxxxxxxxxxxx
Sounds like you didn't need delegation after all. :)

You should be able to use the network service account on the machine for
the app pool identity and have this work as well. A custom service
account should not be needed. When the network service account is used,
the login will appear to the remote resource to be the AD machine account
of the server. So, if you ACL the resource so that the machine account
has the required access, that should work too.

Running the app pool with your domain account is not a good long term
solution. :)

Joe K.

--
Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services
Programming"
http://www.directoryprogramming.net
--
"Justin Rich" <jrich523@xxxxxxxxxxxxxx> wrote in message
news:e%23k6foRBIHA.4956@xxxxxxxxxxxxxxxxxxxxxxx
I configured a custom app pool using the default settings and then used
my domain creds as the identity. one thing to note (for anyone else
reading this) is that you need to add the account to the IIS_WPG group to
allow it to run an app pool.. had me stumped for a min..

this seems to work, and since ive already spent FAR to much time
monkeying with this, im just going to leave it. hopefully i can get them
to create me a service account.. difficult, but they will at least do
that..

I liked it better when i ran small networks and had complete control..
never had problems like this :)

I appreciate your help and detailed responses joe!

Thanks
Justin


"Joe Kaplan" <joseph.e.kaplan@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:eZt9tRRBIHA.3400@xxxxxxxxxxxxxxxxxxxxxxx
Do you absolutely need to access the file share with the credentials of
the authenticated user or can you use a fixed service account (the
so-called trusted subystem architecture)?

If you can use a trusted subsystem design, then this is easy to fix.
You just disable impersonation and make sure your process identity (the
app pool) has the necessary rights on the remote resource.

If you have to delegate and can't configure Kerberos delegation, the
only other way I know of to make this work is to collect plaintext
credentials from the user and log them in locally on the web server.
If you impersonate a token created that way, then delegation is not
required. However, prompting for credentials or using Basic auth to
collect them may not be acceptable to the end users.

Otherwise, if you really need this type of delegated distributed
authentication model, you have to use the stuff that Microsoft gives
you to do this (Kerberos delegation). If your AD guys won't play ball,
you'll need to get the whole politics thing going and address that. :)

Joe K.

--
Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services
Programming"
http://www.directoryprogramming.net
--
"Justin Rich" <jrich523@xxxxxxxxxxxxxx> wrote in message
news:OBimDARBIHA.5752@xxxxxxxxxxxxxxxxxxxxxxx
I dont suppose there is some other adventure i can embark on?
The problem is that i dont run the domain and getting them to do
anything for me is pretty close to impossible.

what are some of my other options? even if they are a bit out there im
willing to try.

Thanks
Justin

"Joe Kaplan" <joseph.e.kaplan@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message news:%23RjhgzQBIHA.5652@xxxxxxxxxxxxxxxxxxxxxxx
You need delegation IF:
- You are using integrated windows auth in your web app
- Your browser users are accessing the web server from a different
machine (are not logged in locally)
- You want to use the credentials of the authenticated web app user
to access the file share (or other remote resource) via impersonation
- The file share is on a different machine than the web server

It sounds to me like all this is true.

If so, simply impersonating the authenticated user will not work.
What will happen is that if the application is not configured for
delegation, the web app process will not be able to delegate and will
instead fall back to an NTLM login to the file share using the
anonymous user for the login. That will almost certainly always fail
and won't give you the results you want anyway.

So, if you need to delegate, you have more work to do. You need to
ensure that:
- Kerberos authentication to the web app is enabled and working
- Kerberos authentication to the remote resource (the file share in
this case) is also working (make sure you are using NetBIOS or DNS
names and not IP addresses, as Kerb doesn't work with IP addresses)
- The app pool identity is trusted for delegation
- The users being authenticated have not been set to disallow
delegation

If your AD domain is 2003 native, you can also use protocol
transition login and constrained delegation. That allows you to have
NTLM auth instead of only Kerberos on the front end web app, so you
can ease one of these restrictions.

Getting all the Kerb auth stuff working can be an adventure, so good
luck!

Joe K.

--
Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services
Programming"
http://www.directoryprogramming.net
--
"Justin Rich" <jrich523@xxxxxxxxxxxxxx> wrote in message
news:OzoYiiPBIHA.4880@xxxxxxxxxxxxxxxxxxxxxxx
I had already set the web config which is why i was able to get the
user info but it seems that when i go to access the file it refuses
to use that account. even when i tried your code it still didnt work.

the link made mention of delegation.. how do i know when thats
needed? im pretty confused. it says "Delegation is a more powerful
form of impersonation and makes it possible for the server process
to access remote resources while acting as the client."
isnt it always the server process? Anything i toss in the cs file i
assume is executed as the server process which in turn is actually
the application pool.

I have already looked in to the delegation and because of how the
network is run i will be unable to do that.

I enabled all of the auditing to see if i can catch the failed
attempt and there are no entries (i did however find some other guy
trying to get on my box)..

Im going to attempt to deploy this on an XP or 2k box rather than a
2k3 because i assume the root of this problem is the application
pool.
if anyone can provide some insight as to whats going on here i would
greatly appreciate it.

Thanks
Justin


"Alexey Smirnov" <alexey.smirnov@xxxxxxxxx> wrote in message
news:1191276328.022414.150600@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Oct 1, 11:10 pm, Jesse Houwing <jesse.houw...@xxxxxxxxxxxxxxxx>
wrote:
Hello Justin,





im having some issues with application security and i was
wondering if
anyone could point me in the direction of some good resources
that
would explain the different levels of security.

the problem im currently having is im trying to make a web app
that
will pull a file from the client (clients are on the lan and
part of
the domain) and its giving me a denied access..

I have set IIS to not allow anon access (verified with
System.Security.Principal.WindowsIdentity.GetCurrent().Name)
which
shows the username correctly.

I assume that whats happening now is its using the application
pool
identity (set to Network Service by default) to go back to the
client
instead of the logged in user creds. I tried messing with the
identity
of the application pool with no luck

FileInfo fi1 = new FileInfo(path) <-- problem line

path resolves to something like \\ip\c$\folder\file.txt

I expect the users of my app to be local admins on the machine.

ASP.NET 2.0

You can set impersonation in the web.config. That should fix your
problem.

http://msdn2.microsoft.com/en-us/library/aa292118(VS.71).aspx

--
Jesse Houwing
jesse.houwing at sogeti.nl- Hide quoted text -

- Show quoted text -

or try

System.Security.Principal.WindowsImpersonationContext
impersonationContext;
impersonationContext =
((System.Security.Principal.WindowsIdentity)HttpContext.Current.User.Identity).Impersonate();

FileInfo fi1 = new FileInfo(path)
...
impersonationContext.Undo();

















.

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