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

Michael-Sangre
Here to help

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

and

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
Gjzawada
Conversationalist

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: https://www.cisco.com/c/en/us/support/docs/csa/cisco-sa-20160218-glibc.html.

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. 

Michael-Sangre
Here to help

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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