Using Session Data to Look for Worm Activity

Currently a slew of worms are scanning port 3127 TCP, looking for systems infected by MyDoom.A. They include MyDoom.B, Doomjuice, and Vesser.

I collect session data using a variety of means, including Argus. I have the Argus daemon write what it sees into a directory. The elaborate date in the file name is a result of calling the date command like so:

DATE=`/bin/date "+%Y%m%d-%H%M%S"`

When the process is running, it looks like this:

/usr/local/src/argus-2.0.6/bin/argus_bpf -c -d -i ngeth0 -w
 /nsm/argus/20040206-085201.bourque.taosecurity.com.ngeth0.arg - ip

This process stores Argus data in the /nsm/argus directory. To quickly search the directory, I use the following at the command line:

-bash-2.05b$ for i in `ls`; do ra -n -r $i - dst port 3127 |
 grep -v stream >> /tmp/3127.ra; done

This yields results like the following:

28 Jan 04 16:47:32    tcp  80.181.182.157.2391   ->        myIP.3127  RST
28 Jan 04 16:47:33    tcp  80.181.182.157.2391   ->        myIP.3127  RST
28 Jan 04 16:47:34    tcp  80.181.182.157.2391   ->        myIP.3127  RST
03 Feb 04 00:31:04    tcp  63.208.193.241.3127   ->        myIP.3127  RST
03 Feb 04 17:32:55    tcp    24.168.219.7.3127   ->        myIP.3127  RST
03 Feb 04 21:42:12    tcp    212.58.12.98.3723   ->        myIP.3127  RST
03 Feb 04 21:42:13    tcp    212.58.12.98.3723   ->        myIP.3127  RST
03 Feb 04 21:42:14    tcp    212.58.12.98.3723   ->        myIP.3127  RST
04 Feb 04 03:55:59    tcp     129.1.61.23.3228   ->        myIP.3127  RST
04 Feb 04 03:55:59    tcp     129.1.61.23.3228   ->        myIP.3127  RST
...continues until today...

The RST means the connection attempt ended with a RST. From my small vantage point on the Internet, scanning for port 3127 TCP appeared 28 Jan 04, and my system did not respond.

This sort of analysis is part of Network Security Monitoring. This is how you verify your machine is not compromised with a minimum amount of effort.