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HTTP Parsing Vulnerabilities in Check Point Firewall-1

   Original release date: February 05, 2004
   Last revised: --
   Source: US-CERT

   A complete revision history can be found at the end of this file.

Systems Affected

     * Check Point Firewall-1 NG FCS
     * Check Point Firewall-1 NG FP1
     * Check Point Firewall-1 NG FP2
     * Check Point Firewall-1 NG FP3, HF2
     * Check Point Firewall-1 NG with Application Intelligence R54
     * Check Point Firewall-1 NG with Application Intelligence R55

Overview

   Several versions of Check Point Firewall-1 contain a vulnerability that
   allows remote attackers to execute arbitrary code with administrative
   privileges. This allows the attacker to take control of the firewall,
   and in some cases, to also control the server it runs on.

I. Description

   The Application Intelligence (AI) component of Check Point Firewall-1
   is an application proxy that scans traffic for application layer
   attacks once it has passed through the firewall at the network level.
   Earlier versions of Firewall-1 include the HTTP Security Server, which
   provides similar functionality.

   Both the AI and HTTP Security Server features contain an HTTP parsing
   vulnerability that is triggered by sending an invalid HTTP request
   through the firewall. When Firewall-1 generates an error message in
   response to the invalid request, a portion of the input supplied by the
   attacker is included in the format string for a call to sprintf().

   Researchers at Internet Security Systems have determined that it is
   possible to exploit this format string vulnerability to execute
   commands on the firewall. The researchers have also determined that
   this vulnerability can be exploited as a heap overflow, which would
   allow an attacker to execute arbitrary code. In either case, the
   commands or code executed by the attacker would run with administrative
   privileges, typically "SYSTEM" or "root". For more information, please
   see the ISS advisory at:

          http://xforce.iss.net/xforce/alerts/id/162

   The CERT/CC is tracking this issue as VU#790771. This reference number
   corresponds to CVE candidate CAN-2004-0039.

II. Impact

   This vulnerability allows remote attackers to execute arbitrary code on
   affected firewalls with administrative privileges, typically "SYSTEM"
   or "root". Failed attempts to exploit this vulnerability may cause the
   firewall to crash.

III. Solution

   Apply the patch from Check Point

   Check Point has published a "Firewall-1 HTTP Security Server Update"
   that modifies the error return strings used when an invalid HTTP
   request is detected. For more information, please see the Check Point
   bulletin at:

     http://www.checkpoint.com/techsupport/alerts/security_server.html

   This update prevents attackers from using several known error strings
   to exploit this vulnerability. It is unclear at this time whether there
   are other attack vectors that may still allow exploitation of the
   underlying software defect.

   Disable the affected components

   Check Point has reported that their products are only affected by this
   vulnerability if the HTTP Security Servers feature is enabled.
   Therefore, affected sites may be able to limit their exposure to this
   vulnerability by disabling HTTP Security Servers or the Application
   Intelligence component, as appropriate.
     _________________________________________________________________

   This vulnerability was discovered and researched by Mark Dowd of ISS
   X-Force.
     _________________________________________________________________

   This document was written by Jeffrey P. Lanza.
     _________________________________________________________________

   This document is available from:
   http://www.us-cert.gov/cas/techalerts/TA04-036A.html
     _________________________________________________________________

   Copyright 2004 Carnegie Mellon University.

   Revision History
   Feb 05, 2004:  Initial release
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