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Re: SSL VPN's from LAN to WAN
From: Tremaine Lea <tremaine () gmail com>
Date: Wed, 12 Dec 2007 09:31:38 -0700

I'd definitely recommend blocking all outbound vpn access. A good starting point would be to check your outbound logs for all activity on 443, explicitly allow the connections to business related ssl sites and then block the rest. It may also be worth appending your information security policy (cuz you have one, right? *grin*) allowing for outbound vpn access but only under certain terms that they must sign off on.

One option is to create a separate network within your network and allow contractors to connect out to their company vpn on a different vlan, and restrict access to the vlan by MAC address and port security - of course, it would be best if they supplied their own laptop/pc for that connection so you can keep corporate and non-corporate assets segregated.


Tremaine Lea
Network Security Consultant
Intrepid ACL
"Paranoia for hire"

On 11-Dec-07, at 3:08 AM, fac51 wrote:

Hi All,

I would like some advice on a situation that is new to me.

I have just discovered that some contractors that are on our corporate LAN have managed to install (Half Install) VPN Clients that allow them to connect directly back to their LAN (RDP'ing into their Desktops etc.) The desktops they are using here are locked down but still allow some VPN functionality.

The VPN connects over 443 out of our network then to their Firewall as concentrator.

Implications that I can think of are;

1. All traffic to and from us is encrypted and therefore we cannot monitor. 2. They can see network drives and could be stealing info. (although they don't have much access) 3. Any infections at their site could propogate to us (that could happen anyway I suppose via email)

My first reaction is one of horror but am I over reacting?

If my worst fears are confirmed I will need to block them. To do this I was thinking of blocking all traffic to and from their firewall however apparently some access to remote services is required by other staff.


kind regards,


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