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Re: CheckPoint FW1 HTTP Security Hole
From: Scott Walker Register <scott.register () us checkpoint com>
Date: Sun, 24 Feb 2002 20:25:30 +0200

Check Point Statement on use of HTTP Connect commands
As noted in the original posting, no escalation of privilege is granted via the use of HTTP Connect commands with the 
FireWall-1 HTTP security server; that is, connections via the HTTP security server are blocked unless specified in the 
rule base. Therefore, a properly constructed rule base mitigates the effect of this malicious use of a valid function 
of an HTTP proxy.
Check Point is taking action to give administrators enhanced control of this type of connection, and will offer that 
improved functionality in the next product update.
  From: Volker Tanger <volker.tanger () discon de>
  Subject: CheckPoint FW1 HTTP Security Hole
  Date: Tue, 19 Feb 2002 16:05:22 +0100 
  To: bugtraq () securityfocus com

Hash: SHA1


A quite known proxy vulnerability was found for FW1 V4.1 SP5 (plus
hotfixes) - thanks to Ryan Snyder for announcing the first bits on
Firewall-1 mailing list.

If you connect to a server you are allowed to connect to via HTTP
proxy (e.g. a common rule is "Any / WebServer / http->ressource").
Then use the CONNECT method to connect to a different server, e.g.
an internal mailserver.

      you =
      Webserver =
      Internal Mailserver =

      Rule allows:  Any  Webserver http->ressource

      connect with "telnet 80" to the webserver and enter
      CONNECT / HTTP/1.0

      response: mail server banner - and running SMTP session e.g.
      to send SPAM from.

You can connect to any TCP port on any machine the firewall
can connect to. Telnet, SMTP, POP, etc.

Restrictions found:
      - connects are only possible if the firewall module
        is allowed access (i.e. via policy/properties,
        specific rules or "Any  (dst) (svc)..." rules
      - you have to allow "CONNECT" - is enabled if you allowed
        "Tunneling" (General tab) connection method or did not
        delete the "*" in "Other" Methods (Match tab)

Fast workarounds:
      - Change your ressource settings to filter out CONNECT
        commands, i.e.
              * disable HTTP tunneling
              * check that "Other" method is specified NOT to
                match CONNECT (i.e. remove the default wildcard)
      - disallow access from the firewall module (->Properties)
      - replace in all your rules containing the service
        HTTP+Resource this part with plain HTTP. Yes, you loose

        some content security but at least you don't compromise

        your other servers

The thing that really concerns me is, that this general problem has
been known to be an issue with plain HTTP proxies like the Squid since
ages (see e.g. http://www.squid-cache.org/Doc/FAQ/FAQ-10.html#ss10.14).
And why didn't Checkpoint prevent or at least document this?


- --

- -------------------------------------------------------------------
volker.tanger () discon de                                 discon GmbH
IT-Security Consulting                           Wrangelstrasse 100
http://www.discon.de/                         10997 Berlin, Germany
- -------------------------------------------------------------------
PGP-Fingerprint: 5323 a4f7 a7c2 b8ef 4653 05ce d2ea 2b74  b94c c68e
Version: GnuPG v1.0.6 (MingW32) - WinPT v0.0.3 (WINNT)
Comment: This is the WinPT config test


---------------End of Original Message-----------------

Scott.Register () us CheckPoint com  ||  FireWall-1 Product Manager
               Check Point Software Technologies, Inc.
2255 Glades Road    /    Suite 324A     \  Boca Raton, FL  33431
Voice: 561.989.5418 | Fax: 561.997.5421  |   02/24/02   20:25:30

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