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Alert (TA04-036A)

HTTP Parsing Vulnerabilities in Check Point Firewall-1

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


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 the server it runs on.


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:

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


This vulnerability allows remote attackers to execute arbitrary code on affected firewalls with administrative privileges, typically "SYSTEM" or "root".


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:

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

Revision History

  • 02/05/2004: Initial release
    02/06/2004: Updated Solution section
    02/06/2004: Updated Overview and Impact sections

    Last updated

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