Microsoft Security Bulletin MS03-034: Flaw in NetBIOS Could Lead to Information Disclosure (Q824105)

2003-09-04T00:00:00
ID SECURITYVULNS:DOC:5046
Type securityvulns
Reporter Securityvulns
Modified 2003-09-04T00:00:00

Description

-----BEGIN PGP SIGNED MESSAGE-----


Title: Flaw in NetBIOS Could Lead to Information Disclosure (824105) Date: 03 September 2003 Software:

  • Microsoft Windows NT 4.0 Server
  • Microsoft Windows NT 4.0, Terminal Server Edition
  • Microsoft Windows 2000
  • Microsoft Windows XP
  • Microsoft Windows Server 2003

Impact: Information Disclosure Max Risk: Low Bulletin: MS03-034

Microsoft encourages customers to review the Security Bulletins at: http://www.microsoft.com/technet/security/bulletin/MS03-034.asp http://www.microsoft.com/security/security_bulletins/ms03-034.asp


Issue:

Network basic input/output system (NetBIOS) is an application programming interface (API) that can be used by programs on a local area network (LAN). NetBIOS provides programs with a uniform set of commands for requesting the lower-level services required to manage names, conduct sessions, and send datagrams between nodes on a network.

This vulnerability involves one of the NetBT (NetBIOS over TCP) services, namely, the NetBIOS Name Service (NBNS). NBNS is analogous to DNS in the TCP/IP world and it provides a way to find a system's IP address given its NetBIOS name, or vice versa.

Under certain conditions, the response to a NetBT Name Service query may, in addition to the typical reply, contain random data from the target system's memory. This data could, for example, be a segment of HTML if the user on the target system was using an Internet browser, or it could contain other types of data that exist in memory at the time that the target system responds to the NetBT Name Service query.

An attacker could seek to exploit this vulnerability by sending a NetBT Name Service query to the target system and then examine the response to see if it included any random data from that system's memory.

If best security practices have been followed and port 137 UDP has been blocked at the firewall, Internet based attacks would not be possible.

Mitigating Factors:

  • Any information disclosure would be completely random.
  • By default, the Internet Connection Firewall (ICF), which is available with Windows XP and Windows Server 2003, blocks the ports that are used by NetBT.
  • To exploit this vulnerability, an attacker would have to be able to send a specially-crafted NetBT request to port 137 on the target system and then examine the response to see whether any random data from that system's memory is included. In intranet environments, these ports are usually accessible, but systems that are connected to the Internet usually have these ports blocked by a firewall.

Risk Rating:

  • Low

Patch Availability:

  • A patch is available to fix this vulnerability. Please read the Security Bulletins at

http://www.microsoft.com/technet/security/bulletin/ms03-034.asp http://www.microsoft.com/security/security_bulletins/ms03-034.asp

for information on obtaining this patch.

Acknowledgment:

Mike Price of Foundstone Labs, http://www.foundstone.com


THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

-----BEGIN PGP SIGNATURE----- Version: PGP 8.0.2

iQEVAwUBP1YR+o0ZSRQxA/UrAQHi6Qf9HgzfxBkc+2SVFSPHZt/2BomUIVPWz9l/ t6+wUzVkGiCtEegBFWeaNgjfaVFdkCuACbZkbX3PUIGbBdlrLMul1jNYu0hz5KeN 5tXFq5BF1paQBJz9pLzDYM7fTMJQzPjLIAN88cykS0XX1JgIT+gSbx3kTPK5Qxg8 M1xw0AnLYIv8kmNoEaXbcrWvPgD89qENYjtPFyNN8PX3dtM3ceJup/i6JUOHcS0x y7pLQpnsDV5tFRt0RpsEhnXafp19AKITgHSK99KPEOd2OUMdjyn76Jwao3yra0Si LEknLRqWt0PWEP1oZvJnLugL8s1+W8p4N60y04qm/9iFY7FzkFfAiw== =zeO4 -----END PGP SIGNATURE-----


You have received this e-mail bulletin because of your subscription to the Microsoft Product Security Notification Service. For more information on this service, please visit http://www.microsoft.com/technet/security/notify.asp.

To verify the digital signature on this bulletin, please download our PGP key at http://www.microsoft.com/technet/security/notify.asp.

To unsubscribe from the Microsoft Security Notification Service, please visit the Microsoft Profile Center at http://register.microsoft.com/regsys/pic.asp

If you do not wish to use Microsoft Passport, you can unsubscribe from the Microsoft Security Notification Service via email as described below: Reply to this message with the word UNSUBSCRIBE in the Subject line.

For security-related information about Microsoft products, please visit the Microsoft Security Advisor web site at http://www.microsoft.com/security.