Invalid TCP header flags

From: kyle.r.maxwellat_private
Date: Mon Jul 08 2002 - 13:22:21 PDT

  • Next message: Crist J. Clark: "Re: Invalid TCP header flags"

    We're seeing occasional TCP traffic with FIN-RST-ACK or FIN-PSH-RST-ACK set
    in the header. The strange part is that it's always set for port 110 (this
    is in fact a legitimate POP server). The traffic is observed inside the
    firewall; I don't have an IDS sensor outside.
    
    Could this just be port scanning, OS fingerprinting, a broken stack, or
    something else? I've googled around but haven't found too much useful info,
    other than to see that other folks have seen similar stuff.
    
    --
    Kyle Maxwell
    InfoSec Engineer
    Global Security Operations Center
    Verizon International Security
    Office  - 972-929-1287
    Hotline - 972-929-1290
    kyle.r.maxwellat_private
    
    
    
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