ISS "Stumbler" advisory questions

From: Joe Stewart (
Date: 06/20/03

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    Date: Fri, 20 Jun 2003 10:08:22 -0400

    From the X-Force "Stumbler" advisory:
    > X-Force has been tracking reports of suspicious and widespread Internet
    > traffic with a TCP Window size of 55808. A substantial amount of traffic
    > captured from sites around the world point to a new distributed port
    > scanning system.
    ... snip ...
    > Each agent attempts to map IP addresses and open ports corresponding to
    > each IP address by sending a TCP SYN packet with a random destination port.

    This doesn't appear to be the same pattern of activity seen since May. Many
    people have reported activity from a single spoofed IP to a single destination
    IP from a random but non-varying source port to a random but non-varying
    destination port - for weeks at a time. I've seen this on several networks we
    montor. I see no way this could even pretend to be an effective distributed

    Intrusec seems to feel that the trojan they found is a copycat; someone
    created a trojan to try and match the described behavior/traffic with winsize
    55808. Probably someone's idea of a joke on the infosec community. The files
    ISS describe match the files Intrusec described, so why does ISS/X-Force feel
    that Stumbler is the true source of the traffic?


    Joe Stewart, GCIH 
    Senior Intrusion Analyst
    LURHQ Corporation
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