Security Incidents mailing list archives

Re: Nimda mostly infects /8-locally.


From: Bryan Andersen <bryan () visi com>
Date: Tue, 18 Sep 2001 22:40:47 -0500

Thomas Roessler wrote:

It seems that Nimda has some strong locality properties
when spreading.

Evaluating logs on a server which listens on an obscene number of
virtual network interfaces with consecutive IP addresses, all in the
same /24, I'm seeing the following distribution of "classical"
netmasks (/n*8) with respect to the attacking hosts (unique IP
addresses encountered in the logs):

        /16      1
        /8    1127
        /0     242

These numbers are to one IP address only.

    total  outside smaller spaces
---------  ----------------------
/0    158      9
/8    149    133
/16    16     16
/24     0      0

The /24 I'm in is sparcely populated.  

It does seam to be favoring the /16 some over the /8.

At this time 10:40pm CDT (-500) I'm mostly seeing repeats, with 
only a few new ip addresses.




-- 
|  Bryan Andersen   |   bryan () visi com   |   http://www.nerdvest.com   |
| Buzzwords are like annoying little flies that deserve to be swatted. |
|   -Bryan Andersen                                                    |

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