Re: YA Apache DoS attack

From: Dag-Erling Coidan Smørgrav (dag-erliat_private)
Date: Sat Aug 08 1998 - 02:40:56 PDT

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    I have gotten a certain amount of response to my posting about the
    Apache DoS attack. Rather than follow up to each in particular, I'll
    summarize my replies here.
    
    Several of you have pointed out that the Apache team *does* have an
    email address for reporting security vulnerabilities. I'm very glad to
    hear that; if I ever find a bug in Apache again, I'll report it to
    that address and give them a week. Yesterday however, I was slightly
    under the shock of the discovery, and slightly pissed at not being
    able to find such an address anywhere. I apologize for letting this
    cloud my judgement and not giving the Apache team a chance to fix this
    before it hit the lists.
    
    Others have pointed out that setting appropriate resource limits for
    the server will solve the problem. My reaction to that is that it does
    not solve anything; it merely circumvents a nasty bug by causing the
    server to die when the bug manifests itself. It does not change the
    fact that Apache has a memory consumption curve which is roughly a
    polynomial function of the size of its input.
    
    To those of you who wrote along the lines of "I'll have to shut down
    my server until a fix comes out", that should not be necessary.
    Although not a good permanent solution, resource limits will allow
    your server to get through this relatively unscathed until a fix comes
    out. If you get hit badly by the kiddies, reduce MaxRequestsPerChild
    to a low single-digit number; this will prevent bloated httpd
    processes from hanging around too long.
    
    Those of you who tried the exploit and experienced server SIGSEGVs or
    "Broken Pipe" error messages from the exploit already have resource
    limits in place.
    
    To the Apache team: sorry for springing this on you without warning.
    Despite nasty bugs like this, you generally do a very good job of
    writing a nice web server. Keep up the good work.
    
    DES
    --
    Dag-Erling Smørgrav - dag-erliat_private
    



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