RE: Web app based on .net - best practice?

you definitely want to put your business logic on a different subnet seperated by a firewall...

you could check out the Microsoft prescriptive guidance for ASP.NET:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnnetsec/html/secnetlpMSDN.asp

This has extensive coverage of the areas you mention.

It is possible to configure DCOM/COM+ to use one RPC port per application, in addition to 135. This gives you a practical and measurable way to let RPC through firewalls.

Check out http://www.gotdotnet.com/team/rojacobs/samples/dev359.zip for sample code for this.

However, if you are using .NET why not use Web Services and therefore HTTP as the inter-zone communication channel? Or are you restricted by windows 2000 / legacy COM components?

Do you need help?

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With Windows 2003 Server you can expose legacy COM+ applications as Web Services simply by checking a box in the COM+ GUI.

hth
Spence

-----Original Message-----
From: Mads Rasmussen [mailto:mads@opencs.com.br] Sent: 23 April 2003 14:42
To: webappsec@securityfocus.com

Imagine I have a .net based application

I thought it would be a good idea to have the presentation layer (asp) in a DMZ and the business layer (components in VB and C#) in a safe site behind a firewall. The communication in between would take place with RPC calls. I know that RPC is not considered secure but we have a firewall in between the DMZ and the safe site (not a guarantee things work out, I know)

I wondered what Microsoft says about the division of the layers, is there a recommendation or some kind of best practice for something like this?

Do any know of pointers to information about this?

My concern is that if the whole application was based in the DMZ, it would be hard to control injections and stuff like that. With the division we can control (somewhat) what calls goes to the safe site (business layer).

Do you need more help?

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I would love to hear opinions on this matter

Thanks,

Mads

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