Hi All,

Has anyone got any experience with ISE Profiling in relation to static IP 
devices and NMAP Scanning?

I have the situation where we have some statically addressed devices that do 
not support EAP.

Scenario;

I have a ‘catch-all’ MAB authorisation rule matching the built in ‘Wired MAB’ 
condition but delivering a downloadable ACL permitting return traffic back to 
ISE to support NMAP scanning (and dhcp but not relevant for this scenario).

Once authenticated ISE nmap scans the device and detects the device (finds 
various ports, SNMP hostnames etc), lets call it a RICOH printer, it sends the 
COA to the switch and it re-runs through the authorisation rules and now 
matches a more specific rule which permits full access to the network.

All great…. Until

I configure another device (evil hax0r’s laptop) with the same mac/ip address, 
unplug the printer and plug in my laptop.. I gain full network access and 
seemingly I’m never ‘re-profiled’ (within my test 12 hour window anyway, plenty 
of time to wreak havoc)

Question;

Why would ISE not re-scan on each subsequent authentication? I have the NMAP 
probe enabled, and NMAP scan is in the policy for ‘ricoh-printer’.

If ISE inherently has some block that prevents a re-run the nmap scan – what is 
the point of profiling/nmap scans? ISE is simply using standard MAB at this 
point, we might as well have stuck with Cisco ACS.

Whilst I appreciate an NMAP scan could take anywhere from 5-10 seconds, we 
would simply scale up the environment to cater for how many concurrent scans 
would need to take place. Our PSN's are all dual quad cpu's and we’d even be 
happy to dedicate PSN’s as nmap probes, in theory we should be able to crank 
out 10’s if not 100’s of nmap scans simultaneously (which would likely never be 
required scenario anyway).

As we don’t use re-authentication timers a device could be on the network for 
months or even years requiring only 1 nmap scan per host per x weeks/months of 
use. Even then, the amount of the hosts we’d require the full nmap scan on are 
so few, as the majority of our estate is EAP-TLS and doesn’t require nmap 
scanning.

I’m either missing something obvious or Cisco have really missed a trick here 
in relation to static IP devices/NMAP, it seems so sensible to assume there 
would be a endpoint profile comparison post authentication and a CoA sent if 
the host has changed, and I can’t think of a downside of doing so. Even if it 
took 10mins to complete an NMAP scan and feed the info into the DB, at least 
the attacker would be kicked off, in the current scenario the attacker can stay 
on the network until someone realises the printer isn’t printing anymore.

Further;

Im aware I could restrict the printer/potential attackers access with dACL’s 
etc, however Cisco is banging on about ISE and profiling etc, and it seemingly 
can’t even protect the low hanging fruit.


Thanks
SteveH

Steve Housego
Principal Consultant

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