March 28, 2005
Denial of Service in Symantec Norton AntiVirus AutoProtect

Revision History

Risk Impact

Symantec responded to two denial of service (DoS) issues identified in the AutoProtect functionality of the Symantec Norton AntiVirus consumer product. The Information-Technology Promotion Agency-Japan, IPA, reported one situation where a real time scan of a specific file type can cause a system crash, Blue Screen of Death (BSOD), with both Symantec Norton AntiVirus 2004 and 2005 Windows applications. This type of file, while not malicious on its own, could be maliciously introduced either remotely from outside the system through email or over http, or internally by an authorized user to disrupt service on a targeted system.

Scanning specific file modifications using the “SmartScan” feature of AutoProtect in the Symantec Norton AntiVirus 2005 application can cause the other DoS issue reported by the Japan Computer Emergency Response team, JPCERT. Any malicious use of this DoS would require authorized access to the targeted system to implement.

Affected Products
Symantec Norton AntiVirus 2004
Symantec Norton Internet Security 2004 (Professional)
Symantec Norton System Works 2004 (Professional)
Symantec Norton AntiVirus 2005
Symantec Norton Internet Security 2005
Symantec Norton System Works 2005 (Premier)

Issue One:
JPCERT reported a DoS, impacting Symantec Norton AntiVirus 2004 and 2005 products, that occurs when the Auto-Protect module of Symantec Norton AntiVirus scans a specific file type.

Symantec Auto-Protect module loads in Windows as a virtual device driver. Running in the background, Auto-Protect scans files for viruses, Trojan, and worms. Auto-Protect scans any files that are received from any source, such as the Internet, removable disks, or email attachments and scans any time that files are accessed, such as when a file is copied, moved, run, or opened. Auto-Protect intercepts any run, open, or create activity and scans the file before allowing the action to continue.

In the issue, when Auto-Protect was invoked to scan a particular file type, e.g. introduced on a CD, copied and pasted into the system, etc., the resultant scan caused the system to hang and generate a general protection fault error, or BSOD requiring a system reboot to clear.

Issue Two:
IPA reported a DoS problem that impacts Symantec Norton AntiVirus 2005 products and only when the SmartScan feature of AutoProtect is enabled.

SmartScan was developed as an alternative to the "scan all files" feature of NAV Auto-Protect and Manual Scan. SmartScan scans a specific group of file extensions as well as all .exe and .doc files. SmartScan will scan .exe and .doc files even if the file extensions for the .exe and .doc files have been changed.

In this instance, under certain circumstances with SmartScan enabled, renaming a file stored on a network share can induce a system crash when the modification kicks off SmartScan. Based on the file write for the name change, SmartScan will be invoked to scan the file, which can result in excess CPU consumption and ultimately a system crash.

Symantec Response
Symantec product engineers confirmed both issues impacting Symantec’s Auto-Protect feature in Symantec Norton AntiVirus and have developed and released a patch for all impacted products through Symantec LiveUpdate. Customers running Automatic LiveUpdate should already be updated.
To manually update via Symantec LiveUpdate, users should:

Symantec is unaware of any adverse customer impact from either of these issues

A CVE candidate number will be requested from The Common Vulnerabilities and Exposures (CVE) initiative. This advisory will be revised as required once the CVE candidate number has been assigned. This issue is a candidate for inclusion in the CVE list (, which standardizes names for security problems.

Symantec would like to thank Mr. Isamu Noguchi, who initially identified both issues, for reporting them to the Information-Technology Promotion Agency-Japan and JPCERT. Symantec further thanks IPA and JPCERT for providing the coordination while Symantec resolved the issues.

Last modified on: