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    (SOLVED) Snort detecting INDICATOR-COMPROMISE suspicious .null DNS query

    Scheduled Pinned Locked Moved IDS/IPS
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    • johnpozJ
      johnpoz LAYER 8 Global Moderator
      last edited by johnpoz

      You can tell your resolver to log the queries, but shouldn't snort be saving the packets? And you can view them?

      We already went over all of this..

      An intelligent man is sometimes forced to be drunk to spend time with his fools
      If you get confused: Listen to the Music Play
      Please don't Chat/PM me for help, unless mod related
      SG-4860 24.11 | Lab VMs 2.8, 24.11

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      • NogBadTheBadN
        NogBadTheBad
        last edited by NogBadTheBad

        if you do what i said ages ago you’ll be able to see what is being looked up with a u2spwefoo.

        You could be looking at the logs for ages, DNS is very chatty.

        Andy

        1 x Netgate SG-4860 - 3 x Linksys LGS308P - 1 x Aruba InstantOn AP22

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        • T
          tman904
          last edited by tman904

          I just enabled barnyard2, once I get results I'll run that command. Problem is if it doesn't happen again while running barnyard2. How I'm I suppose to see it? The last time the query for .win happened was April 30th.

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          • T
            tman904
            last edited by tman904

            The mail server was checking domains against spam blacklists. I've confirmed this by matching up timestamps on the server and pfsense.

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            • johnpozJ
              johnpoz LAYER 8 Global Moderator
              last edited by

              So you were getting mail that said it came from .win and .null domains?

              An intelligent man is sometimes forced to be drunk to spend time with his fools
              If you get confused: Listen to the Music Play
              Please don't Chat/PM me for help, unless mod related
              SG-4860 24.11 | Lab VMs 2.8, 24.11

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              • T
                tman904
                last edited by tman904

                The mail server sends DNS queries since it checks the domain name against spam blacklists and If it's on one of the blacklists it rejects the email. Meaning It was the content of the DNS queries that triggered snort, to top it off I put snort on the highest security mode, That combined to create what I thought was a compromised server.

                This also explains why I got alerts on the LAN side as those email clients do the same type of checking.

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                • bmeeksB
                  bmeeks
                  last edited by

                  Dialing Snort up to the "Security" policy is pretty stringent and just asking for false positives. "Connectivity" is fine the majority of the time, especially for admins new to managing an IPS. "Balanced" is the best policy overall once you get your feet wet with IPS management experience. For the vast majority of business networks, the "Balanced" IPS policy offers plenty of security without running the admin crazy checking out false positive all day long.

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                  • T
                    tman904
                    last edited by

                    Thank you for the advice @bmeeks. I'll keep that in mind. 😀

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