[VulnWatch] Corsaire Security Advisory - Sygate Enforcer discovery packet DoS issue

From: advisories (advisories_at_corsaire.com)
Date: 08/10/04

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    To: <vulnwatch@vulnwatch.org>
    Date: Tue, 10 Aug 2004 17:32:15 +0100

    -- Corsaire Security Advisory --

    Title: Sygate Enforcer discovery packet DoS issue
    Date: 20.11.03
    Application: Sygate Enforcer 4.0 and prior
    Environment: Windows NT, 2000, 2003
    Author: Martin O'Neal [martin.oneal@corsaire.com]
    Audience: General distribution
    Reference: c031120-001

    -- Scope --

    The aim of this document is to clearly define an issue that exists with
    the Sygate Enforcer product [1] that will allow a remote attacker to
    provoke a DoS condition.

    -- History --

    Discovered: 20.11.03 (Martin O'Neal)
    Vendor notified: 14.01.04
    Document released: 10.8.04

    -- Overview --

    Sygate Enforcers are described as [2] "network gateway devices that
    enforce host integrity at network access points". Architecturally they
    function as an authenticated, packet-filtering firewall device. The
    Enforcer interacts with the Sygate Security Agent (SAA [the personal
    firewall component]) product and limits access to protected
    networks/hosts to authenticated clients that comply with a predefined

    In practise, the Enforcer device uses a number of proprietary protocol
    exchanges to communicate with other Enforcers and also the SAA product.
    By sending a packet containing a malformed payload to the Enforcer, the
    host service can be forced to stop responding.

    -- Analysis --

    The Sygate Enforcer product sends a discovery packet at one-second
    intervals on all interfaces that have IP bound to them. The packet is a
    UDP datagram, from source port 39999 to destination port 39999, and is
    sent to the local subnet broadcast address.

    If this packet is malformed and replayed to the Enforcer, it will cause
    the Enforcer service to stop unexpectedly, without generating an entry
    within the product's audit trail.

    It is worth noting that the packet that is replayed does not need to be
    sent to the local subnet broadcast address, and can be happily sent to
    any valid unicast address associated with the Enforcer. This means that
    the attacker does not need to be local to the Enforcer to exploit this

    -- Recommendations --

    The Enforcer product should be upgraded to a version that is not
    susceptible to this issue.

    -- Background --

    This issue was discovered using a custom protocol analysis tool
    developed by Corsaire's security assessment team. This tool is not
    available publicly, but is an example of the specialist approach used by
    Corsaire's consultants as part of a commercial security assessment. To
    find out more about the cutting edge services provided by Corsaire
    simply visit our web site at http://www.corsaire.com

    -- CVE --

    The Common Vulnerabilities and Exposures (CVE) project has assigned
    the name CAN-2003-0931 to this issue. This is a candidate for
    inclusion in the CVE list (http://cve.mitre.org), which standardises
    names for security problems.

    -- References --

    [1] http://www.sygate.com
    [2] http://www.sygate.com/products/universal_enforcement.htm

    -- Revision --

    a. Initial release.
    b. Minor revisions.

    -- Distribution --

    This security advisory may be freely distributed, provided that it
    remains unaltered and in its original form.

    -- Disclaimer --

    The information contained within this advisory is supplied "as-is" with
    no warranties or guarantees of fitness of use or otherwise. Corsaire
    accepts no responsibility for any damage caused by the use or misuse of
    this information.

    -- About Corsaire --

    Corsaire are a leading information security consultancy, founded in 1997
    in Guildford, Surrey, UK. Corsaire bring innovation, integrity and
    analytical rigour to every job, which means fast and dramatic security
    performance improvements. Our services centre on the delivery of
    information security planning, assessment, implementation, management
    and vulnerability research.

    A free guide to selecting a security assessment supplier is available at

    Copyright 2004 Corsaire Limited. All rights reserved.

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