SYM04-008, Symantec Client Firewall Remote Access and Denial of Service Issues May 13 2004 06:50PM
Sym Security (secure symantec com)
Symantec Security Advisory


12 May, 2004

Symantec Client Firewall Remote Access and Denial of Service Issues

Revision History

Risk Impact

eEye Digital Security notified Symantec Corporation of four vulnerability
issues they discovered in the Symantec Client Firewall products for
Windows. By properly exploiting these issues, an attacker could render the
targeted system inoperable or execute remote code with kernel-level
privileges on the targeted system.

Affected Components

Symantec Norton Internet Security and Professional 2002, 2003, 2004
Symantec Norton Personal Firewall 2002, 2003, 2004
Symantec Norton AntiSpam 2004

Symantec Client Firewall 5.01, 5.1.1
Symantec Client Security 1.0, 1.1, 2.0(SCF 7.1)

eEye Digital Security notified Symantec of four vulnerabilities they
discovered during product testing on versions of Symantec's client
firewall application. eEye Digital Security found three instances where
remote KERNEL-level access could potentially be gained. Additionally,
they reported a denial of service (DoS) issue that requires a system
reboot to regain system utilization.

All issues occur within routines in the SYMDNS.SYS component.

The first issue is a stack overflow in the processing of DNS responses
caused by improper bounds checking of external input. Successful
exploitation of this issue could result in remote code execution on the
targeted system with kernel-level privileges.

The second issue is a stack overflow in the processing of NetBIOS Name
Service responses that can result in a memory overwrite. If an attacker
could successfully create the conditions required to manipulate this
vulnerability they could potentially execute arbitrary code with
kernel-level privileges.

The third remote execution issue is a potential heap corruption problem
caused by improper bounds checking in the processing of NetBIOS Name
Service responses. If an attacker were to successfully exploit this
condition, they could possibly execute arbitrary code on the targeted
system with kernel-level privileges.

The forth issue is a potential DoS condition caused by improper handling
of DNS response packets. Maliciously configured DNS responses can cause
the targeted system to halt requiring a system reboot to clear the
condition and regain system access.

Symantec Response
Symantec confirmed the vulnerabilities exist in the consumer and corporate
Symantec Client Firewall applications as well as in Symantec's Norton
AntiSpam 2004 application. Symantec product engineers have developed
fixes for the issues and released patches for all impacted products
through Symantec LiveUpdate and technical support channels.

Clients running consumer versions of the affected products who regularly
run a manual Symantec LiveUpdate should already be protected against this
issue. However, to be sure they are fully protected, customers should
manually run Symantec LiveUpdate to ensure all available updates are
* Open any installed Symantec product
* Click on LiveUpdate in the toolbar
* Run LiveUpdate until Symantec LiveUpdate indicated that all installed
Symantec products are up-to-date
* Depending on the application, system may require a reboot to effectively
update available fixes.

Clients running the corporate versions of Symantec Client Firewall or
Symantec Client Security should download and apply patches obtained
through their appropriate support channels.

Symantec is not aware of any active attempts against or customer impact
from this issue.


The Common Vulnerabilities and Exposures (CVE) initiative has assigned
Candidate names to these issues.
Issues one, two and three are assigned under CVE Candidate Name,

The fourth issue, the Denial of Service in NetBIOS Name Service is
assigned CVE Candidate Name, CAN 2004-0445

These are candidates for inclusion in the CVE list (http://cve.mitre.org),
which standardizes names for security problems.

Symantec appreciates the cooperation of the eEye Digital Security research
team in identifying this issue.

Symantec Product Security Contact:
Symantec takes the security and proper functionality of its products very
seriously. As founding members in the Organization for Internet Safety,
Symantec follows the process of responsible disclosure. Symantec also
subscribes to the vulnerability guidelines outlined by the National
Infrastructure Advisory Council (NIAC). Please contact
secure (at) symantec (dot) com [email concealed] if you feel you have discovered a potential or actual
security issue with a Symantec product.

Symantec strongly recommends using encrypted email for reporting
vulnerability information to secure (at) symantec (dot) com. [email concealed] The Symantec Product
Security PGP key can be obtained here.

This advisory is available on-line at


Copyright (c) 2004 by Symantec Corp.
Permission to redistribute this alert electronically is granted as long as
it is not edited in any way unless authorized by Symantec Security
Response. Reprinting the whole or parts of this alert in any medium other
than electronically requires permission from symsecurity (at) symantec (dot) com. [email concealed]

The information in the advisory is believed to be accurate at the time of
publishing based on currently available information. Use of the
information constitutes acceptance for use in an AS IS condition. There
are no warranties with regard to this information. Neither the author nor
the publisher accepts any liability for any direct, indirect, or
consequential loss or damage arising from use of, or reliance on, this

Symantec, Symantec products, and SymSecurity are registered trademarks of
Symantec Corp. and/or affiliated companies in the United States and other
countries. All other registered and unregistered trademarks represented in
this document are the sole property of their respective companies/owners.

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