How to secure exchange active sync from external hackers

I was just told today that all the VPs of the company were receiving smartphone/PDAs that are capable of receiving e-mail via exchange active sync.  Unfortunately the phones are arriving today and I have to have them functioning by the end of the day.

 I’ve scrambled through the Internet and found all the info I need to get this to work but I am missing one piece…securing my exchange.  In order for the phone to communicate back to the exchange server I need to have it exposed to the Internet.  Could someone please give me a suggestion for the best way to secure my exchange server with what I have in my current environment?  I know that I can use Microsoft ISA server or I can install a front-end exchange server and place that in my DNZ but I don’t currently have either in my network.  What I’m looking for is a solution I can do today with what I have so I can have the phones working by the end of the day without my exchange server being totally exposed to hackers.

This is my environment:  I have an exchange server 2003 SP2. I have a checkpoint firewall (NGX R60) that protects my internal network from the outside.  Currently my exchange server is not directly exposed to the outside world.  All of my incoming and outgoing e-mails go through a Sonicwall e-mail gateway located in our DMZ.

Not all the phone/pdas we are receiving support MSFP so that means some of the phones can take advantage of the new direct push that comes with SP2 and other phones still have to respond to an sms message sent by the provider.  Whatever security solution has to take that into consideration.

This is what I know to do so far: I can NAT my exchange server to an external IP address through the firewall.  I can create a rule in checkpoint to only allow traffic to that IP on port 80 – I believe port 80 is the port with which active synch uses.  I know it also uses 443 if your using SSL but I will not be using that for now.  

Also the smartphones will be using dynamic Ips so there is no way to set up a rule that will allow only certain external IP address to the exchange server so I will have to set my firewall rule to allow all external traffic access to my server on port 80.

I’m nervous about the security risk so I would like to know what is the best way to secure my exchange server using the technology I currently have.

Also I would appreciate if anyone could comment on what they currently use as a security solution for their exchange active sync setup.

Thanks in advance
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sgh_abaConnect With a Mentor Commented:

You can setup your SonicWall to port forward, port 80, to the Internal Exchange server.  Then open up incoming port 80 on the checkpoint to the SonicWall (for the one IP).


Kumar_Jayant123Connect With a Mentor Commented:

Using the certs would be the Best way to secure the Exchange Server No Doubts.

As you said your mails are coming through Sonicwall e-mail gateway, does it supports your OWA too? The OWA (HTTP) and the Active sync work in the same manner and if it does you dont need to worry.

Other way of doing it would be do a port forwarding on your Firewall to the Exchange server on port 80.

One more thing... There are two ways in which your Mobile Device synchronize with Exchange
1. Active sync
2. Hot Sync

For active Sync there is no need to make any changes but i am not very sure abt the HOTSYNC.

Have a look of this article,Kb=PalmSupportKB,ts=Palm_External2001,case=obj(17681)

Hope this helps..
securityresearchConnect With a Mentor Commented:

I run quite the same setup, but use another firewall. Port 80 or 443 musst be enabled. You need a valid certificate for 443 so you either buy a really good one which is included in the store of the devices ( and use True Business ID) or you create your own and import it into the device store. If your devices support push mail and security feature pack you are ready to go. if not set up a short poll intervall or condsider the sms solution. since loosing this devices is a big risk i would consider upgrading them all so you can delete mail stores remotely in case of a theft.
Also set up a password policy for the devices. If you are paranoid you can also consider setting up this services behind vpn and instructing the user to make a vpn connection but then push mail wont work.

hope that helps!
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