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Security Advisories Relating to Symantec Products - Norton AntiVirus and Symantec Client Security Email Denial of Service Vulnerability


August 26, 2009

Revision History


Risk Impact


Remote Access Yes
Local Access No
Authentication Required No
Exploit available No


Norton AntiVirus and Symantec Client Security are susceptible to an email denial of Service (DoS) attack which could be triggered by a specially crafted email message.

Affected Products

Product Version Solution
Norton AntiVirus 2005 through 2008 Run LiveUpdate in interactive mode
Norton Internet Security 2005 through 2008 Run LiveUpdate in interactive mode
Symantec AntiVirus Corporate Edition 9.0 MR6 and earlier Update to 9.0 MR7 or later
10.0 all versions Update to 10.1 MR8 or later
10.1 MR7 and earlier Update to 10.1 MR8 or later
10.2 MR2 and earlier Update to 10.2 MR3 or later
Symantec Client Security 2.0 MR6 and earlier Update to 2.0 MR7 or later
3.0 all versions Update to 3.1 MR8 or later
3.1 MR7 and earlier Update to 3.1 MR8 or later
Note: Symantec AntiVirus and Symantec Client Security are vulnerable only if the optional Internet Email Scanning feature has been installed and enabled on the client.

Unaffected Products

Product Version
Norton 360 all
Norton AntiVirus 2009 and later
Norton Confidential all
Norton Internet Security 2009 and later
Symantec Endpoint Protection all


Next Generation Security Software notified Symantec that a specially crafted email could potentially create a Denial of Service (DoS) condition on an end user system. The malicious message would require a significantly longer than normal time to process, which could cause the client system to lose connection with the mail server. The email client will try to download the message again the next time it connects to the mail server, and again lose connection. This cycle would be repeated until the malicious message was deleted from the mail server.

Symantec Response

Symantec has confirmed that this issue exists in the products listed in the Affected Products table above. The vulnerability can be exploited only if the optional Internet Email Scanning feature is enabled on the user’s system.

Symantec is not aware of any customers impacted by this issue, or of any attempts to exploit the issue.


Internet Email Scanning is an optional feature which can disabled if it is not being used. Disabling this feature prevents it from being exploited through this vulnerability.

Updating Norton products

Norton product users who launch and run LiveUpdate regularly have already received an update to address this issue. However, to ensure all available updates have been applied, users can manually launch and run LiveUpdate in interactive mode as follows:

  • Open any installed Norton product
  • Click LiveUpdate
  • Run LiveUpdate until all available product updates are downloaded and installed
  • A reboot may be required, depending on the existing patch level of the affected computer.

Best Practices

As part of normal best practices, Symantec strongly recommends a multi-layered approach to security:

  • Run under the principle of least privilege where possible.
  • Keep all operating systems and applications updated with the latest vendor patches.
  • Run both a personal firewall and antivirus application with current updates to provide multiple points of detection and protection.
  • Be cautious when receiving attachments, executables, and web links through email. Do not open email from unknown senders.
  • Email addresses can easily be spoofed so that a message appears to come from someone you know. If in doubt, contact the sender before opening attachments or following web links.


Symantec thanks Mark Litchfield from Next Generation Security Software (http://www.ngssoftware.com/) for reporting this issue, and coordinating with us on the response.


SecurityFocus, http://www.securityfocus.com, has assigned BID 34670 to this issue

This issues is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. The CVE-ID, CVE-2009-3104 has been assigned for this issue.


Symantec takes the security and proper functionality of our products very seriously. As founding members of the Organization for Internet Safety (OISafety), Symantec supports and follows responsible disclosure guidelines.
Symantec has developed a Software Security Vulnerability Management Process document outlining the process we follow in addressing suspected vulnerabilities in our products.
Symantec Corporation firmly believes in a proactive approach to secure software development and implements security review into various stages of the software development process. Additionally, Symantec is committed to the security of its products and services as well as to its customers’ data. Symantec is committed to continually improving its software security process.
This document provides an overview of the current Secure Development Lifecycle (SDLC) practice applicable to Symantec’s product and service teams as well as other software security related activities and policies used by such teams. This document is intended as a summary and does not represent a comprehensive list of security testing and practices conducted by Symantec in the software development process.
Please contact secure@symantec.com if you believe you have discovered a security issue in a Symantec product. A member of the Symantec Software Security team will contact you regarding your submission to coordinate any required response. Symantec strongly recommends using encrypted email for reporting vulnerability information to secure@symantec.com.
The Symantec Software Security PGP key can be found at the following location:
Permission to redistribute this alert electronically is granted as long as it is not edited in any way unless authorized by Symantec Software Security. Reprinting the whole or part of this alert in any medium other than electronically requires permission from secure@symantec.com.
Last modified on: August 26, 2009
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