Re: [fw-wiz] Variations of firewall ruleset bypass via FTP

From: Darren Reed (darrenrat_private)
Date: Fri Oct 11 2002 - 03:52:30 PDT

  • Next message: Mikael Olsson: "Re: [fw-wiz] Variations of firewall ruleset bypass via FTP"

    Another addendum to add to this story, a quick check of some ftp
    daemons shows they will convert the response to (at least HELP)
    into uppercase.  The IPFilter ftp proxy will not accept that as
    a valid response from a PASV.
    
    e.g.
    
    $ telnet solaris8 ftp
    220 solaris8 FTP server (SunOS 5.8) ready.
    HELP 227 Entering Passive Mode (h1,h2,h3,h4,p1,p2)
    502 Unknown command 227 ENTERING PASSIVE MODE (H1,H2,H3,H4,P1,P2).
    
    So if I may reiterate what I said earlier, what the firewall does
    for data going from the ftp server is not isolated in this problem
    from what the ftp server does to the input.
    
    Darren
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