===================================================================== CERT-Renater Note d'Information No. 2009/VULN351 _____________________________________________________________________ DATE : 08/09/2009 HARDWARE PLATFORM(S) : / OPERATING SYSTEM(S) : Windows Vista, Windows Server 2008, Windows 7 RC running SMB 2.0. ====================================================================== http://blogs.technet.com/msrc/default.aspx http://www.microsoft.com/technet/security/advisory/975497.mspx ______________________________________________________________________ Microsoft Security Advisory 975497 Released Posted Tuesday, September 08, 2009 4:35 PM by MSRCTEAM We’ve just released Microsoft released Security Advisory 975497 that provides information about a new, irresponsibly reported vulnerability in SMB 2.0. Our investigation has shown that Windows Vista, Windows Server 2008 and Windows 7 RC are affected by this vulnerability. Windows 7 RTM, Windows Server 2008 R2, Windows XP and Windows 2000 are not affected by * this vulnerability. The Security Advisory outlines steps that Windows Vista and Windows Server 2008 customers can take to help protect themselves while we work on a security update for this issue. As always, we’ve provided information through Microsoft Active Protections Program (MAPP) as well as the Microsoft Security Response Alliance (MSRA) that they can use to help provide broader protections to customers. We will update you through our security advisory and the MSRC Weblog as we have new information. Thanks Christopher *This posting is provided "AS IS" with no warranties, and confers no rights* _____________________________________________________________________________ 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 ====================================================================== ========================================================= Les serveurs de référence du CERT-Renater http://www.urec.fr/securite http://www.cru.fr/securite http://www.renater.fr ========================================================= + CERT-RENATER | tel : 01-53-94-20-44 + + 151 bd de l'Hopital | fax : 01-53-94-20-41 + + 75013 Paris | email: certsvp@renater.fr + =========================================================