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October 5, 2004
Symantec Norton AntiVirus MS-DOS Reserved Device Name Handling

Revision History

Risk Impact

Symantec Norton AntiVirus consumer products do not effectively scan files with MS-DOS reserved device names once the file is resident on a user's system. This could potentially permit a malicious file disguised as an MS-DOS reserved device file to evade detection prior to attempted execution provided it can be downloaded to or physically placed on the targeted system.

Affected Components
Symantec Norton AntiVirus 2003
Symantec Norton AntiVirus 2004
Symantec Norton AntiVirus 2005

iDefense reported a problem with Symantec's Norton AntiVirus consumer products in effectively scanning files and directories with MS-DOS reserved device names. Device names such as COM1, CON or LPT1 are reserved words, and not intended to be used as directory or file names. In fact, in the early MS-DOS and Win 3.x days, they could not be used as directory or file names. However there are currently ways to create directories or files in Win32 systems using reserved device names that could contain potentially malicious code. Symantec Norton AntiVirus consumer products currently do not consistently scan these types of files during automatic and manual scans. To get such a maliciously configured file on a target system, the attacker would need to either entice the targeted user to visit a location where the malicious file could be downloaded to the target system or have access to the target system to upload or transfer the malicious file.

Symantec Response
Symantec engineers have thoroughly tested this issue on all supported Symantec Norton AntiVirus consumer products. All Symantec Norton AntiVirus consumer products successfully scan incoming email files with MS-DOS reserved device names to detect malicious content. However, scanning of files with MS-DOS reserved device names residing on a system was inconsistent.
Symantec engineers have developed a fix for this issue for Symantec Norton AntiVirus 2004 that is currently available through LiveUpdate. The fix is being incorporated into all other supported Symantec Norton AntiVirus versions and will be available through LiveUpdate when fully tested and released. Symantec is not aware of any active exploits for or customer impact from this issue.

As a part of normal user best practice, Symantec highly recommends a multi-layered approach to security.

  • Users, at a minimum, should run both a personal firewall and antivirus application with current updates to provide multiple points of detection and protection to both inbound and outbound threats.
  • Users should keep vendor-supplied patches for all application software and operating systems up-to-date.
  • Users should be cautious of mysterious attachments and executables delivered via email and be cautious of visiting unknown/untrusted websites or opening unknown URL links.
  • Do not open unidentified attachments or executables from unknown sources or that you didn't request.
  • Always err on the side of caution. Even if the sender is known, the source address may be faked.
  • If in doubt, contact the sender to confirm they sent the attachment and why before opening the attachment. If still in doubt, delete the attachment.

The Common Vulnerabilities and Exposures (CVE) initiative has assigned CVE Candidate name CAN-2004-0920 to this issue.

This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems.

Symantec appreciates the cooperation of the iDefense research team in identifying this issue and coordinating with Symantec in the resolution process.

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-04 15:34:15