RE: [FW1] Secure Client and NAT

[Jeff Hochberg]

Paranoia is a good thing in the world of security, but only to a certain extent.  How do you expect SecuRemote clients to be able to connect to the firewall otherwise?

 

Authenticated topology requests prevent just "anyone" from getting a hold your topology.  Even if a hacker scans your firewall and sees that the ports for retrieving FW-1 topology info are open, they still need to provide a valid username and password before they'll even be able to download it.

 

The negate rule will negate all objects within that rule.  You're probably OK with the way you have your rule currently set up, so don't worry about my negate suggestion too much.

 

-Jeff Hochberg

-----Original Message-----
From: Rafiyq Mondesir [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, March 07, 2001 12:10 PM
To: [EMAIL PROTECTED]; [EMAIL PROTECTED]
Subject: RE: [FW1] Secure Client and NAT

> How does this undermine the use of a stealth rule? 

It undermines the Stealth rule because the idea of the Stealth rule is to hide the net interfaces of the firewall in such a way as to be responseless to any connection attempts directly to them (the interfaces).  Thus, when an attacker sees no response from their scans they are lead to believe that the IP address is not in use, and hopefully they'll be discouraged and move on.

The data contained in the userc.C file gives details about the FW network interfaces and network that the Stealth Rule is supposed to be hiding.  For example, it gives the IP addresses of both nics, the dns name of the FW, and the network subnet behind the firewall.  I am under the impression that this info is supposed to be hidden.  I'll grant that this info by itself is not a major security risk but it provides detail about the network and FW that the FW is supposed to be hiding.  There is also the possibility that this info can be used in conjunction with other illicitly acquired data to ammase a pointed attack that may not have anything to do with the FW.

Perhaps some details about my setup will help to clarify:

• I am using CPfw1-41; SP2.
• My Mgmt Station and FW are on two separate machines.
• I am using IKE.
• "Respond to Unauthenticated Topology Requests" is Disabled.
• Per instruction from CheckPoint Support, I have the SecureClients connect to the ext interface of the FW instead of the Mgmt Server. (I am very close to trying it the other way to see if less info is generated in the userc.C file.)

>Also, when constructing your Client Encrypt rule, make sure to put the firewall object(s) in the >destination field and negate them so that even VPN users can't make a direct connection to the >firewall through a SecuRemote session.

I tried this this morning but the Negate option negates everything in the box; not just the item I selected. (?)

R.

  Jeff Hochberg <[EMAIL PROTECTED]> wrote:

No there is not.

 

How does this undermine the use of a stealth rule?  Disable the "Respond to Unauthenticated Topology Requests" option in Policy->Properties in order to enable SSL authenticated topology downloads to prevent just "anyone" from getting your userc.C file.

 

Also, when constructing your Client Encrypt rule, make sure to put the firewall object(s) in the destination field and negate them so that even VPN users can't make a direct connection to the firewall through a SecuRemote session.

 

-Jeff Hochberg

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Rafiyq Mondesir
Sent: Tuesday, March 06, 2001 11:21 AM
To: [EMAIL PROTECTED]
Subject: [FW1] Secure Client and NAT

Helo.

Does anyone know if its possible to use a NAT'ed address of the firewall's external interface as the point of connect in the SecureRemote Client.  In otherwords, say the external interface of of my firewall is publicly addressable: 111.111.111.111, and I plan giving it a NAT'ed address of 222.222.222.222 to be used by my clients for topology updates and VPN connections.  Is this possible?

The reason I want to do this is because the file: userc.C, which is located on the client, contains (in clear text) several firewall and network details that undermine the use of a Stealth Rule, and thus compromises my security policy.

Any advice would be appreciated.

Regards,

R.

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