Re: Apache DoS attack?

From: Micha³ Zalewski (lcamtufat_private)
Date: Tue Dec 30 1997 - 08:34:47 PST

  • Next message: Mark Lowes: "Re: Apache DoS attack?"

    Apache patch by Mark Lowes:
    
    [...]
    + /* Compress multiple '/' characters into one */
    + /* To prevent "GET //////..." attack */
    [...]
    
    After a few tests I discovered that Apache first looks for files
    [index|homepage].[html|shtml|cgi] (probably it makes over 32000
    chdirs :), then dies, throwing 'filename too long' error into logs.
    Client gets 'Forbidden' response and disconnects. But httpd child
    process still stays in background, wasting large amount of CPU time
    and system resources. Note it happends _only_ after this error,
    so '//...' sequence must as long as it's possible (about 7 kB).
    The PERFECT httpd patch should also fix httpd's cleanup, to make
    httpd a little more stable :)
    
    _______________________________________________________________________
    Michal Zalewski [tel 9690] | finger 4 PGP [lcamtufat_private]
    =--------- [ echo "while [ -f \$0 ]; do \$0 &;done" >_;. _ ] ---------=
    



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