Kerberos Man In The Middle Attack: is this feasible?

Calimer0 cryos98 at
Mon Oct 13 18:52:35 EDT 2003

Hi all,
I'm tryng to understand Kerberos strenghts and flaws, I would like to
know your opinion about the feasibility of the attack described below.
Here it is:
An attacker puts his machine A between the legitimate client C and an
application server AS using an ARP spoofing attack, and then
transparently forwards network traffic between C and AS until C sends
the KRB_AP_REQ message. Once KRB_AP_REQ is captured, the attacker
launchs a Denial Of Service attack on C, and forwards KRB_AP_REQ to
AS. Is the attacker able to succesfully authenticate to AS?
For my level of knowledge, the response is yes, but the attacker
probably must spoof IP address of C, and his possibilities are limited
the missing knowledge of session keys included in KRB_AP_REQ.
something wrong?
thanks in advance


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