If you click on the name of the 'Reporting Device, for example 'ABCD-IDS-1', MARS will show you the 'Raw Event' (as received from the sensor). This will help you show if the IPS is sending the zero port or its the MARS.
Some signatures don't report the port number properly, I don't this this is a bug or by design :) (Since the signature already says 'HTML' )
Btw, I see this false positive on one of our customer's all the time....
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...