Re: Stopping Arp poison attacks

[Jason Ostrom <justiceguy () pobox com>]

Hello P.Entester,

In addition to the good suggestion you have already received on using 
Dynamic ARP Inspection (DARP) on Cisco Catalyst switches, here is 
another one that I have recommended to clients (since it is so trivial 
to inject MiTM attacks).

Good Security design in VLANs, server placement, and Administrative user 
workstations:

Think of placing all of your servers in a separate VLAN network.

Then, place all of your Administrative users in an "Administrative 
workstation" VLAN.  This is a locked down VLAN in which only hard-coded, 
wired ports of Administrator workstations are allowed access.  You can 
even implement a control of "port security" and only allow the MAC 
address of Administrator's on these workstations.

Regular users are in a third VLAN, "users".

Since you are assuming that the only way to ARP Poison is when the 
attacker is sourced from the same VLAN (You can't poison remote VLANs), 
this does reduce the risk of exposure to MiTM ARP attacks.  The attacker 
would only be able to sniff traffic from other regular users in the 
"user" VLAN to remote networks.

In this design, the malicious insider (or pentester) would only see 
success if their machine was terminated into the server VLAN or Admin 
workstation VLAN.  It is assumed that all regular users are placed in 
the "users" VLAN.  This greatly reduces the risk.  I am also assuming 
that the risk is sniffing cleartext credentials of Administrator access 
to these systems.

Ping me offline if you want to discuss this in much more details.  This 
is just a start.  Hope this helps.

All the best,
Jason O.





P. Entester wrote:
> Hello there,
>
> I am not a networking expert, but in my work as a pentester i often use 
> arp poison attacks to intercept interesting traffic.
> If i recommend our customers to bind the MAC addresses of mission 
> critical servers' network interfaces to their respective ports on the 
> routers and switches, does that migitate most of the threat or am i 
> missing something important?
>
> Thanks in advance for your reply.
>
> Peter.
>
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This List Sponsored by: Cenzic

Concerned about Web Application Security? 
Why not go with the #1 solution - Cenzic, the only one to win the Analyst's 
Choice Award from eWeek. As attacks through web applications continue to rise, 
you need to proactively protect your applications from hackers. Cenzic has the 
most comprehensive solutions to meet your application security penetration 
testing and vulnerability management needs. You have an option to go with a 
managed service (Cenzic ClickToSecure) or an enterprise software 
(Cenzic Hailstorm). Download FREE whitepaper on how a managed service can 
help you: http://www.cenzic.com/news_events/wpappsec.php 
And, now for a limited time we can do a FREE audit for you to confirm your 
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