Trying to determine of an message is just a normal operation or concern

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Trying to determine of an message is just a normal operation or concern

We are getting one alert with regularity and one not so much.


PROTOCOL-DNS glibc getaddrinfo A record stack buffer overflow attempt - 2 incidents in a 24 hour period


INDICATOR-COMPROMISE suspicious .null dns query - 3 incidents in a 24 hour period.


The Protocol-DNS is infrequent and points to one of the domain controllers using Comcast DNS servers as forwarders.


The Indicator-compromise is some Andriod device. 


I am trying to track these down.


What I am trying to understand is are these normal or not.



2 Replies 2

The volume of alerts within that timeframe isn't too exceptional, but still bears review.


The first one is a little bit more high level than the second.  The PROTOCOL-DNS alert was first discovered a few years back, and is tagged as CVE-2015-7547.  Not specifically a major threat, but there was a known vulnerability found a few years ago that affected quite a number of Cisco devices.  More information on that can be found here:

The second, INDICATOR-COMPROMISE, depends a little more if you happen to have a PCAP of traffic from that device.  It could be nothing, could be indicator of something else, but if you can pull a full packet capture on it, that should give you a little more info of where it lies. In the meanwhile doesn't hurt to isolate that Android client until you get a closer look at it.


Sidenote, but the above could depend on the tier you have your IDS/IPS settings at.  Balanced is typically my SOP on deployment, I've found Security to trigger a number of false positives. 


Depending on any other issues on the network and how long its been since the last review, I always suggest to people to get a security audit completed, either through a VAR or a smaller firm. 

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Thank you for your insight.  I will track down and follow your advice and see what we can do.


Thank you

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