Re: Blocking Nimda and kin

From: Brett Glass (brettat_private)
Date: Thu Nov 08 2001 - 15:00:47 PST

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    You have a good point. How would you guard against this sort of
    spoofing? Require several rapid fire hits before blocking, 
    perhaps?
    
    Also, it turns out that the "%400,404a" is erroneous. This was
    a mistake on my part that stemmed from misunderstanding of the
    Apache documentation. It's better just to use %a there, since 
    adding the "400,404" in the middle can create a malformed
    command in certain unusual circumstances. (No harm will be done, 
    though.)
    
    By the way, Apache runs its master process as root and demotes 
    all the others it spawns to a uid of your choosing. The master
    process opens the log files, so yes, the command is run as root.
    Note that no user input is used in the command, so it's not
    possible to execute a command of your choosing via this mechanism.
    
    --Brett
    
    At 03:46 PM 11/8/2001, Peter W wrote:
    
    >This is very cool stuff. So I can get someone to view an HTML page|email
    >with code like <IMG alt="" height="0" width="0" hspace="0" vspace="0"
    >src="http://brettglass.example.com/winnt/system32/cmd.exe">, I can easily
    >prevent them, or anyone else coming from the same space, from reaching your
    >Web server. Get some AOL users to read the messages and bye-bye to all the
    >AOL proxy server traffic. Get lots of usenet "victims", and even if they
    >don't care about your Web site, man, your routing table suddenly looks bad.
    >
    >Very (un)cool.
    >
    >-Peter
    >
    >P.S. If that exec sh route thing actually works, does that mean your httpd 
    >is running as root?
    



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