RE: Unicode Attack

From: James C Slora Jr (Jim.Sloraat_private)
Date: Thu Nov 14 2002 - 15:19:59 PST

  • Next message: Mike Lewinski: "Re: Unicode Attack (FOLLOW UP)"

    Looking for some enlightenment. Comments and question inline.
    
    Information Security wrote Wednesday, November 13, 2002 1:27 PM
    > > 2002-11-12 13:00:37 210.201.100.253 - x.x.x.17 80 GET
    > > /scripts/..%5c../..%5c../..%5cwinnt/system32/cmd.exe /c+dir 200 1849 321
    > > 31 HTTP/1.1 63.241.137.233
    > > Mozilla/4.0+(compatible;+MSIE+5.01;+Windows+NT+5.0) - -
    
    > It's been my experience that the actual URL probably sent to your server
    was
    > /scripts/..%255c../..%255c../..%255cwinnt/system32/cmd.exe?/c+dir.  If you
    > type that into your browser, you'll probably have success.
    
    This fits my experience exactly. The attack performed from a browser or
    script uses %255c.. but Snort always logs it as %5c.
    
    > You would see this entry on any proxy device in front of the web server.
    > IIS and Snort (IMHO) appropriately run a single URL decode on the
    > request, which pretty much follows URI RFC specs, so that's not really a
    bug.
    
    Are you saying that Snort has performed one level of Unicode translation
    before it creates its hex-level packet dumps? This seems to fit the output,
    but it contradicts the expectation that Snort is displaying exactly what was
    on the wire in hex format.
    
    
    
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