4003 is a known problem with DNS servers. We added a benign trigger in the NSDB as of the upcoming S44 signature update. Best solution is to filter out your DNS servers as sources and destinations.
5366 is looking for a non-printable chararcter (aka shell code) in a HTTP request's URI or arguments. We're not searching to whole request. According to our research, only printable characters (0x00-0x7F) "should" appear in the URI or arguments of a HTTP request. I say "should" because we've been proven wrong before. If you like, we'd be happy to anaylize any log files / traffic traces. You can email them directly to me at firstname.lastname@example.org.
And for a nice segue, yes the 3604 problem can be solved by upgrading to 4.0 sensors. 3.1 sensors don't have a solid notion of who is the client and who is the server. 4.0 fixed this.
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...