You *might* (I've never tried) be able to use application inspection capability of the ASA to drop this traffic, although it would be limited and much easier/robust to use the IDS functionality. You could create a regex based class-map. In the document link provided by Farrukh, look for this:
hostname(config-cmap)# match [not] username regex [regex_name |
If someone tries to login as either root or administrator, have them electrocuted...wait, I guess that's not one of the options. either drop,reset, or rate limit the connection (I haven't tested but it might be fun to see if you can "tar pit" them using rate limiting).
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...