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Microsoft Security Bulletin MS03-034: Flaw in NetBIOS Could Lead to Information Disclosure (Q824105)
From: "Microsoft" <0_51911_04BF067D-4CF8-4245-B5C1-58573E5746A8_US () Newsletters Microsoft com>
Date: Wed, 3 Sep 2003 17:46:48 -0700
-----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. 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- Microsoft Security Bulletin MS03-034: Flaw in NetBIOS Could Lead to Information Disclosure (Q824105) Microsoft (Sep 03)