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15 July, 2002
Symantec Personal and Desktop Firewall Denial of Service Buffer Overflow


@stake notified Symantec of a denial of service problem with outgoing http request through the http filter component on the Symantec Norton Internet Security 2001 personal firewall. Certain malformed requests resulted in a general protection fault (GPF) on the system.

Components Affected
Symantec Norton Internet Security 2001
Symantec Norton Personal Firewall 2001
Symantec Desktop Firewall 2.0
Symantec Desktop Firewall 2.01

The security professionals with @stake discovered a buffer overflow condition in the handling of outgoing http requests by the http filter on the Symantec Norton Internet Security 2001. During Symantec's testing this issue was found to impact the Symantec Norton Personal Firewall 2001 as well. The buffer overflow condition overwrites the first three bytes of the EDI register causing a kernel exception, resulting in a GPF on the targeted system and requiring a reboot.

The GPF is the result of improper error checking in the array allocated to store the hostname specified in the outgoing connection. By supplying an abnormally long hostname in the outgoing http request, the buffer in the http filter is overrun causing the kernel exception and the GPF.

This exception occurs whether the firewall rules permit outgoing http connections or not.

Symantec Response
Symantec engineers verified the buffer overflow condition exists in Symantec's Norton Internet Security 2001, Symantec's Norton Personal Firewall 2001 as well as Symantec's Desktop Firewall 2.0 and 2.01. They have further determined that the GPF does not occur in the latest release of Symantec's Norton Personal Firewall 2002, Norton Internet Security 2002, Norton Internet Security 2002 Professional Edition nor the Symantec Client Security, Symantec's integrated antivirus, intrusion detection and firewall replacement for Symantec Desktop Firewall.

However, Symantec takes any product issue such as this very seriously. We are developing a patch for Symantec Norton Internet Security 2001, and Personal Firewall 2001 to address this issue. The patch will be available via LiveUpdate when completed. We are further enhancing the capabilities of future Symantec products to provide additional protection against these types of issues.

There are some circumstances that greatly mitigate the risk associated with this issue. The buffer overflow condition identified by @stake occurs only in outgoing http requests through the Symantec Norton Internet Security, Personal Firewall and Symantec Desktop Firewall product's http filter.

Any attempt to launch an attack of this nature requires the attacker to either have or be able to gain local access to the targeted system in order to initiate the http request or cause the system user, through a malicious email attachment or by directing the user to a malicious web site, to download and execute malicious code on their system.

Symantec recommends using a multi-layered approach to security. Users, at a minimum, should run both personal firewall and antivirus applications 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 further be wary of mysterious attachments and executables delivered via email.

Do not open attachments or executables from unknown sources. Always err on the side of caution.

Even if the sender is known, be wary of attachments if the sender does not explain the attachment content in the body of the email. You do not know the source of the attachment.

If in doubt, contact the sender before opening the attachment. If still in doubt, delete the attachment without opening it.

Symantec takes the security and proper functionality of our products very seriously. Symantec appreciates the coordination of Ollie Whitehouse and @stake, Inc. in identifying and providing technical details of areas of concern as well as working closely with Symantec so we could properly address the issue. Anyone with information on security issues with Symantec products should contact symsecurity@symantec.com.

The Common Vulnerabilities and Exposures (CVE) initiative has assigned the name CAN-2002-0663 to this issue.

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

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 14:56:30 PDT