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Corsaire Security Advisory - Sygate Enforcer discovery packet DoS issue
From: "advisories" <advisories () corsaire com>
Date: Tue, 10 Aug 2004 17:31:47 +0100
-- Corsaire Security Advisory --
Title: Sygate Enforcer discovery packet DoS issue
Application: Sygate Enforcer 4.0 and prior
Environment: Windows NT, 2000, 2003
Author: Martin O'Neal [martin.oneal () corsaire com]
Audience: General distribution
-- Scope --
The aim of this document is to clearly define an issue that exists with
the Sygate Enforcer product  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  "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 --
-- 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
-- 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.
- Corsaire Security Advisory - Sygate Enforcer discovery packet DoS issue advisories (Aug 10)