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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2009.1269.2 Vulnerabilities in SMB Could Allow Remote Code Execution 9 September 2009 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: SMB Publisher: Microsoft Operating System: Windows Vista Windows Server 2008 Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated Denial of Service -- Remote/Unauthenticated Resolution: Mitigation CVE Names: CVE-2009-3103 Original Bulletin: http://www.microsoft.com/technet/security/advisory/975497.mspx Comment: We have been informed that whilst Windows 7 RTM is not vulnerable to this issue, Windows 7 Release Candidate (RC) is. Anyone using this product should take the same migitation steps outlined by Microsoft. Revision History: September 9 2009: Added information regarding Windows 7 RC September 9 2009: Initial Release - --------------------------BEGIN INCLUDED TEXT-------------------- Microsoft Security Advisory (975497) Vulnerabilities in SMB Could Allow Remote Code Execution Published: September 08, 2009 Version: 1.0 General Information Executive Summary Microsoft is investigating new public reports of a possible vulnerability in Microsoft Server Message Block (SMB) implementation. We are not aware of attacks that try to use the reported vulnerabilities or of customer impact at this time. We are actively working with partners in our Microsoft Active Protections Program (MAPP) to provide information that they can use to provide broader protections to customers. Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs. Microsoft is concerned that this new report of a vulnerability was not responsibly disclosed, potentially putting computer users at risk. We continue to encourage responsible disclosure of vulnerabilities. We believe the commonly accepted practice of reporting vulnerabilities directly to a vendor serves everyone's best interests. This practice helps to ensure that customers receive comprehensive, high-quality updates for security vulnerabilities without exposure to malicious attackers while the update is being developed. Affected Software Windows Vista, Windows Vista Service Pack 1, and Windows Vista Service Pack 2 Windows Vista x64 Edition, Windows Vista x64 Edition Service Pack 1, and Windows Vista x64 Edition Service Pack 2 Windows Server 2008 for 32-bit Systems and Windows Server 2008 for 32-bit Systems Service Pack 2 Windows Server 2008 for x64-based Systems and Windows Server 2008 for x64-based Systems Service Pack 2 Windows Server 2008 for Itanium-based Systems and Windows Server 2008 for Itanium-based Systems Service Pack 2 Mitigating Factors Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of this issue. The following mitigating factors may be helpful in your situation: * Firewall best practices and standard default firewall configurations can help protect networks from attacks that originate outside the enterprise perimeter. Best practices recommend that systems that are connected to the Internet have a minimal number of ports exposed. In this case, the SMB ports should be blocked from the Internet. * In Windows Vista, if the network profile is set to "Public", the system is not affected by this vulnerability, since unsolicited inbound network packets are blocked by default. * Windows 7 and Windows Server 2008 R2 are not affected by this vulnerability. Workarounds Workaround refers to a setting or configuration change that does not correct the underlying issue but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality: * Disable SMB v2 To modify the registry key, perform the following steps: Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. 1. Click Start, click Run, type Regedit in the Open box, and then click OK. 2. Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services 3. Click LanmanServer. 4. Click Parameters. 5. Right-click to add a new DWORD (32 bit) Value. 6. Enter smb2 in the Name data field, and change the Value data field to 0. 7. Exit. 8. Restart the "Server" service. You can do this in two ways: 9. Open up the computer management MMC, navigate to Services and Applications, click Services, right-click the Server service name and click Restart. Answer Yes in the pop-up menu. 10. From a command prompt with administrator privileges, type net stop server and then net start server. Impact of workaround. Host will not be able to communicate using SMB2. How to undo the workaround: 1. Click Start, click Run, type Regedit in the Open box, and then click OK. 2. Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services 3. Click LanmanServer. 4. Click Parameters. 5. Double-click smb2, and change the Value data field to 1. 6. Exit. 7. Restart the "Server" service. You can do this in two ways: 8. Open up the computer management MMC, navigate to Services and Applications, click Services, right-click the Server service name and click Restart. Answer Yes in the pop-up menu. 9. From a command prompt with administrator privileges, type net stop server and then net start server. * Block TCP ports 139 and 445 at the firewall These ports are used to initiate a connection with the affected component. Blocking TCP ports 139 and 445 at the firewall will help protect systems that are behind that firewall from attempts to exploit this vulnerability. Microsoft recommends that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. For more information about ports, see TCP and UDP Port Assignments. [1] Impact of Workaround: Several Windows services use the affected ports. Blocking connectivity to the ports may cause various applications or services to not function. Some of the applications or services that could be impacted are listed below: * Applications that use SMB (CIFS) * Applications that use mailslots or named pipes (RPC over SMB) * Server (File and Print Sharing) * Group Policy * Net Logon * Distributed File System (DFS) * Terminal Server Licensing * Print Spooler * Computer Browser * Remote Procedure Call Locator * Fax Service * Indexing Service * Performance Logs and Alerts * Systems Management Server * License Logging Service How to undo the workaround. Unblock TCP ports 139 and 445 at the firewall. For more information about ports, see TCP and UDP Port Assignments. [1] [1] TCP and UDP Port Assignments. http://go.microsoft.com/fwlink/?LinkId=21312 - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 If you believe that your computer system has been compromised or attacked in any way, we encourage you to let us know by completing the secure National IT Incident Reporting Form at: http://www.auscert.org.au/render.html?it=3192 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iD8DBQFKp0M7NVH5XJJInbgRAlgwAJ90R7EsQUb9Rudfis/xeAosrAHEPgCeKArz qBcTob57twnsbsRnLdxDAzo= =DK0g -----END PGP SIGNATURE-----