Re: [logs] nimda web server logs

From: Sweth Chandramouli (loganalysisat_private)
Date: Fri Jun 14 2002 - 12:24:14 PDT

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    On Fri, Jun 14, 2002 at 12:27:19PM +0200, wolfgangat_private wrote:
    > No requests for *.cif where seen in this case, and no requests for repair/sam
    > either.
    	In which case, what is it about the requests that makes
    you think they are related to the ones Tina was seeing?  Hmm... I feel
    like this problem needs to be better defined...
    	In my world, a Nimda scan is one with a fairly constant
    and short time delta between requests to machines on the same network,
    and whose GET request string matches the following pseudo-grammar:
    
    nimda:               base_dir traversal_string [ desired_file | command ]
    base_dir:            /^(scripts|msadc|_mem_bin|_vti_bin|[cd])$/i
    desired_file:        'Admin.dll'
                       | 'httpodbc.dll'
    command:             command_interpreter command_string
    command_interpreter: '/winnt/system32/cmd.exe?/c'
                       | 'root.exe?/c'
    command_string:      tftp_command | local_exec
    local_exec:          'dir'
    
    	, where I'm leaving traversal_string and tftp_command
    undefined for now (both because I'm lazy and because I don't think it
    will affect the problem definition significantly), and assuming the
    parser uses forward slashes to separate tokens.
    	I think Tina's scans aren't Nimda, then, because they have
    a different time signature (relatively long irregular pauses between
    requests, as though someone were thinking about what to do next), and
    because they have either a different desired_file ('winnt/repair/sam')
    or a different local_exec ('dir+c:\\*.cif/s/b').
    	So, for these other scans that people are reporting: do
    they match my definition of Nimda above, or not?  If not, how
    specifically are they different?
    
    	(Jay's original list of Nimda signatures to loganalysis
    also included the local_exec component 'echo+test+message+>test.msg"',
    but I'm fairly certain that further examination of his logs would reveal
    that that was actually a manual scan that just happened to look vaguely
    Nimda-ish.)
    
    	-- Sweth.
    
    -- 
    Sweth Chandramouli      Idiopathic Systems Consulting
    svcat_private      http://www.idiopathic.net/
    
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