Software Engineering Institute

Symantec offers a suite of corporate and consumer security products including a firewall application. The firewall application includes a SYMDNS.SYS driver, which is responsible for validating NBNS and DNS responses. There is a vulnerability in the routine responsible for processing incoming NBNS responses which could result in heap memory corruption. This routine fails to perform adequate bounds checking on the NBNS response packets. By supplying a specially crafted NBNS packet, an attacker could potentially overwrite arbitrary locations in memory.

According to the Symantec Advisory, the following products are affected:

Consumer:
Symantec Norton Internet Security and Professional 2002, 2003, 2004
Symantec Norton Personal Firewall 2002, 2003, 2004
Symantec Norton AntiSpam 2004

Corporate:
Symantec Client Firewall 5.01, 5.1.1
Symantec Client Security 1.0, 1.1, 2.0(SCF 7.1)

An unauthenticated, remote attacker could cause a denial of service condition or potentially execute arbitrary code with kernel privileges on a vulnerable system. According to the eEye Digital Security Advisory, in order for this vulnerability to be exploited, the firewall must be configured to allow NetBIOS Name Service (NBNS) traffic. This configuration is not present by default.

Apply Patch

Symantec recommends that clients running corporate versions of the affected products apply patches obtained through their appropriate support channels.

Use LiveUpdate
Symantec recommends that clients running consumer versions of the affected products use the LiveUpdate feature to ensure all updates are installed. According to Symantec, this can be done as follows:

• Open any installed Symantec product
• Click on LiveUpdate in the toolbar
• Run LiveUpdate until Symantec LiveUpdate indicated that all installed Symantec products are up-to-date
• Depending on the application, system may require a reboot to effectively update available fixes