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July 28, 2003
Denial of Service Vulnerability in Symantec Quarantine Server

Medium to High

Symantec Central Quarantine Server (qserver.exe) consumes 100% of the CPU when a remote user connects to the user configurable TCP listener port and abnormally terminates the connection.

Components Affected
Norton AntiVirus Corporate Edition version 7.61
Symantec Anti Virus Corporate Edition version 8.01
Symantec Anti Virus Corporate Edition version 8.1

A user with access to the internal corporate network can cause 100% CPU usage by the Symantec Central Quarantine Server. This occurs when a user connects to the Symantec Central Quarantine Server (qserver.exe) on the user configurable TCP listening port and abnormally terminated the connection prior to sending data. This can cause the Symantec Quarantine Server service to consume 100% CPU utilization on the affected server. To regain normal functionality, the Quarantine service must be restarted.

UPDATE - A second vulnerability has been discovered and fixed. The CPU usage of qserver.exe jumps to 100% when a user connects to the Symantec Central Quarantine Server port without sending any data. The CPU usage stays at this high level until the client terminates the connection.

Mitigating the risk - The risk from this vulnerability is greatly reduced if operating with a perimeter firewall that blocks telnet connections to the internal network as a part of normal security best practices. With this configuration, the vulnerable version of Symantec Central Quarantine Server is only accessible by an authorized user on the internal network and is not exploitable by outside sources.

Symantec Response
Customers will need to download the appropriate version of Quarantine server and perform the following steps:

  1. Uninstall the existing version of Quarantine Server. Quarantine Console is not affected -- it is not necessary to uninstall Quarantine Console.
  2. Reboot
  3. Download and extract the appropriate version of Quarantine Server depending on your version of SAV:
  4. Run QSERVER\setup.exe to install the new version of Quarantine Server
  5. Reboot
  6. It will be necessary to re-configure Quarantine Server after reinstallation.
For reference, after installation the new file versions for qserver.exe will be:
  • For QServer 2.6 ->
  • For QServer 3.11 ->
  • For QServer 3.2 ->

Note: Customers using Quarantine server shipped prior to 2.6 (shipped with NAV 7.5x, for example) are urged to upgrade to one of these new builds to address the issue.

The discovery and documentation of this vulnerability was conducted by the Qualys Security Research Team. Symantec Corporation would like to thank Qualys Security Research Team for identifying and working with us to resolve this issue.

For more information about the Qualys Security Research Team, visit their website at http://www.qualys.com or send email to research@qualys.com

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 the principles of responsible disclosure. Symantec also subscribes to the vulnerability disclosure guidelines outlined by the National Infrastructure Advisory Council (NIAC).

Please contact secure@symantec.com if you feel you have discovered a security issue in a Symantec product. A Symantec Product Security team member will contact you regarding your submission. Symantec strongly recommends using encrypted email for reporting vulnerability information to secure@symantec.com. The Symantec Product Security PGP key can be found at the end of this message.

Symantec has developed a Product Vulnerability Response document outlining the process we follow in addressing suspected vulnerabilities in our products. This document is available below.

PDF Symantec Vulnerability Response Policy PGP Symantec Product Vulnerability Management PGP Key

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Last modified on: Monday, 25-Oct-2004 15:13:36 PDT
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