OSEC

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Subject: Re: [PEN-TEST] Your opinions ... more info
From: St. Clair, James (JStClairVREDENBURG.COM)
Date: Tue Oct 31 2000 - 12:13:42 CST


I'd say stick the VPN. I agree, afaik Win2k makes VPNs fairly simple. Your
client seems neither willing or able to truly take on the significance of
handling certificates that precludes the emperor from being without clothes.

Jim

-----Original Message-----
From: Jim Miller [mailto:MillerJFABSSB.COM]
Sent: Tuesday, October 31, 2000 12:45 PM
To: PEN-TESTSECURITYFOCUS.COM
Subject: [PEN-TEST] Your opinions ... more info

Thank you for all of your responses. It was late and I neglected to include
some significant details. I will try to make all clarifications here. Keep
in mind my job function: I am an IT auditor. My job is to reduce technical
business risk. I am consulting to my client, who is not all that
cooperative and forthcoming, and appears from my experience not to
understand completely the technology being deployed. But that may just be
smoke and mirrors to keep me from interfering.

Objective:
Is the certificate authentication process adequate for the cash mgt
application, or is a VPN recommended? All other issues are off target.

Configuration:
On the outside of the firewall is Cisco 1720 with public addressing. There
is an intrusion detection server connected to it, and of course it has
connections to the firewall and to the Net. On the inside of the firewall
is the internal network using proprietary addressing. The DMZ/firewall
island uses proprietary addressing, and this is where the cash mgt
application and the certificate server are to be located, probably both on
the same box. The firewall is configured to protect the island from both
inside and outside access.

Certificates:
The bank will issue its own certificates using MS Certificate Server. They
will not use the recommended method, certificate hierarchy. They will
instead manually set up and issue certificates to clients when a request is
approved. The certificates will be installed in MS IE by our support at
client sites after receipt via email of the notification of certificate
approval. Any detection of certificate compromise will be addressed by
revocation and re-issuance to the client using the manual / approval
process.

Passwords:
The cash mgt application controls password issuance and policy enforcement.
The password data is located with the CMI application on the firewall
island. Passwords are set up by a client security admin, who sets up client
users. We don't need to get into this, as it is obvious that application
based authentication is a weak control at best. [And to add insult to
injury, the password length will be 6 bytes.] The issue is the reliance on
the certificate schema versus the VPN. We could argue forever about the
effectiveness of authentication by logonid/password, and I'd rather focus on
the issue.

VPN Solution:
Windows 2000 Server and Windows 2000 clients was the solution I was
recommending as a stronger solution. Given what I have read, I could not
see where this solution would add any support burden over the certificate
solution. This solution uses client/server IP tunneling with PPTP/L2TP,
MS-CHAP v.2, and certificate authentication. See:
http://www.microsoft.com/NTServer/commserv/deployment/planguides/VPNSecurity
.asp From what I read, it is simple to implement.
http://www.techrepublic.com/article.jhtml?src=search&id=r00220001018jim02.ht
m and is a much more secure solution for an application with high risk. It
also would allow the use of NT password policy enforcement, a significant
improvement over the application password schema.

Reasons for not using the VPN solution:
 From the responses I received from IT staff, I was under the impression
that they were recommending a vendor's solution without due consideration of
the security problem. I could not see, based on what I read, that the VPN
solution would add any more support burden than the certificate schema, as
they insisted. But I have never administered a VPN. Am I missing something
here? What is the burden of administering a VPN to 50 clients who retain
their configuration and use it daily?

SSL:
SSL is to be used to secure the packets from view by the public over the
Net. A debatable point is whether this solution is equal to the security
provided by IP tunneling using the MS products above, and if I made a
mistake saying 132 bit rather than 128 bit, it's a moot point.

Firewall:
A penetration test was run on the firewall and it was reported that 3 ports
were left open. I was privy only to the summary report, and was told that
the open ports were really not a problem, as "they only appeared to an
outsider to be open. They were truly secured.". After learning more, I
found a respected source who agreed that open is open. The point being that
this certificate schema is only as strong as the firewall. It's a Cisco PIX
Firewall Router, and I'm told not to worry, "It's an industry standard.".
What is your opinion?

Additional:
The client base will not exceed 200, so scaling is not really an issue.
Whatever solution is implemented, it will be from Microsoft. I can't fight
city hall.
I'm told the client browser screen will show we are using HTTPS, not HTTP.
There is no requirements document and no design specs. This is typical for
small IT shops. They just wing it.
There will be legal contracts with the customer/client, again a moot point,
since the issue is the use of VPN as compared to certificates alone.
Physical security of the client is a recognised issue. The client can be
compromised any number of ways if accessible. Again, not the issue under
consideration here.

I hope this will allow us to focus in on the target: certificates alone
versus VPN.

Thanks.

Jim Miller, CISA, CDP
VP & IS Audit Mgr
First American Bank Texas
Bryan, Texas 77805-8100
979/361-6515
801/835-5546
millerjfabssb.com