Secunia

eEye Digital Security has discovered multiple vulnerabilities in various Symantec firewall products, which can be exploited by malicious people to cause a DoS (Denial of Service) or compromise a vulnerable system.

1) A boundary error within the "SYMDNS.SYS" driver when processing certain NBNS (NetBIOS Name Service) datagrams can be exploited to cause a stack-based buffer overflow by sending a specially crafted NBNS response to a vulnerable system.

Successful exploitation allows execution of arbitrary code with kernel Ring 0 privileges, but requires that incoming NBNS traffic (port 137/UDP) is allowed (not default setting).

2) An error within the "SYMDNS.SYS" driver when processing certain DNS (Domain Name Service) datagrams can be exploited to halt the system by sending a specially crafted DNS response to a vulnerable system.

3) An error within the "SYMDNS.SYS" driver when processing certain NBNS datagrams can be exploited to corrupt the heap by sending a specially crafted NBNS response to a vulnerable system.

Successful exploitation may allow execution of arbitrary code with kernel Ring 0 privileges, but requires that incoming NBNS traffic (port 137/UDP) is allowed (not default setting).

4) A boundary error within the "SYMDNS.SYS" driver when processing certain DNS datagrams can be exploited to cause a stack-based buffer overflow via a specially crafted DNS response containing an overly long canonical name in the CNAME field of a resource record.

Successful exploitation allows execution of arbitrary code with kernel Ring 0 privileges. This can reportedly be exploited successfully with all ports filtered, and all intrusion rules set due to a design flaw.

NOTE: This advisory has been rated "Extremely critical" because the last vulnerability may be worm potential. The vulnerability is very similar to the "ICQ Response Buffer Overflow" vulnerability in various ISS products, which was already exploited by the "Witty" worm the day after it was disclosed to the public (see "Other References" section for more information about this vulnerability and the worm).

Solution
Patches are available via the LiveUpdate feature and technical support channels.

Provided and/or discovered by
1) Derek Soeder, eEye Digital Security.
2) Barnaby Jack, Karl Lynn, and Derek Soeder, eEye Digital Security.
3) Karl Lynn, eEye Digital Security.
4) Barnaby Jack and Karl Lynn, eEye Digital Security.

Changelog
Further details available in Customer Area

Original Advisory
Symantec:
http://securityresponse.symantec.com/avcenter/security/Content/2004.05.12.html

eEye Digital Security:
http://www.eeye.com/html/Research/Advisories/AD20040512A.html
http://www.eeye.com/html/Research/Advisories/AD20040512B.html
http://www.eeye.com/html/Research/Advisories/AD20040512C.html
http://www.eeye.com/html/Research/Advisories/AD20040512D.html

Other references
Further details available in Customer Area

Deep Links
Links available in Customer Area