odd host scans to random addressess

From: Russell Fulton (r.fultonat_private)
Date: Tue Aug 21 2001 - 16:11:20 PDT

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    Over the last 24 hours I have seen 3 scans from these 3 IP addresses.
    (I assume two are spoofed -- two don't respond to pings and one is
    firewalled). Scans consist of single tcp ACKs sent from each source.
    
    Here is a sample of the traffic:
    
    22 Aug 01 08:02:38           tcp   64.94.188.247.50906  ?>    130.216.14.121.221   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   209.191.132.6.50906  ?>    130.216.14.121.221   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp  209.191.156.89.50906  ?>    130.216.14.121.221   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   64.94.188.247.50907  ?>    130.216.14.121.221   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   209.191.132.6.50907  ?>    130.216.14.121.221   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp  209.191.156.89.50907  ?>    130.216.14.121.221   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   64.94.188.247.50908  ?>    130.216.14.121.221   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   209.191.132.6.50908  ?>    130.216.14.121.221   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp  209.191.156.89.50908  ?>    130.216.14.121.221   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   64.94.188.247.50906  ?>    130.216.14.121.179   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   209.191.132.6.50906  ?>    130.216.14.121.179   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp  209.191.156.89.50906  ?>    130.216.14.121.179   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   64.94.188.247.50907  ?>    130.216.14.121.179   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   209.191.132.6.50907  ?>    130.216.14.121.179   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp  209.191.156.89.50907  ?>    130.216.14.121.179   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   64.94.188.247.50908  ?>    130.216.14.121.179   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   209.191.132.6.50908  ?>    130.216.14.121.179   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp  209.191.156.89.50908  ?>    130.216.14.121.179   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   64.94.188.247.50906  ?>    130.216.14.121.253   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp   209.191.132.6.50906  ?>    130.216.14.121.253   1        0         0            0           A_
    22 Aug 01 08:02:38           tcp  209.191.156.89.50906  ?>    130.216.14.121.253   1        0         0            0           A_
    
    Three different addresses have been scanned in this manner, but the
    odd thing is that none of them are actually in use. About 1600 ports
    are scanned in just under a minute.
    
    And what do they hope to achieve with ACKs?  Won't the machine respond
    with an RST whether or not the port is open?
    
    
    Russell Fulton, Computer and Network Security Officer
    The University of Auckland,  New Zealand
    
    
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