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 DNS and NBNS responses. There is a buffer overflow vulnerability in the routines responsible for processing incoming NBNS responses. By supplying a specially crafted NBNS packet, an attacker could cause a stack overflow allowing arbitrary locations in memory to be overwritten.

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 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 incoming 137/udp packets. 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