Additional products affected by the Microsoft Windows SMB client remote denial of service vulnerability have been identified.
Microsoft Windows Server 2008 R2 and Windows 7 contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability exists in the SMB client. An unauthenticated, remote attacker could exploit this vulnerability by creating a malicious SMB server and convincing a targeted user to connect to that server. An exploit could cause the targeted user's operating system to stop responding to requests, resulting in a DoS condition.
Exploit code is publicly available.
Microsoft has confirmed this vulnerability in a security bulletin and released updated software.
The following versions of Windows are affected:
Windows 2000 SP4 and prior
Windows XP SP3 and prior
Windows XP Professional x64 Edition SP2 and prior
Windows Server 2003 SP2 and prior
Windows Server 2003 x64 Edition SP2 and prior
Windows Vista SP2 and prior
Windows Vista x64 Edition SP2 and prior
Windows Server 2008 for 32-bit Systems SP2 and prior
Windows Server 2008 for x64-based Systems SP2 and prior
Windows 7 for 32-bit Systems
Windows 7 for x64-based Systems
Windows Server 2008 R2 for x64-based Systems
Windows Server 2008 R2 for Itanium-based Systems
To exploit this vulnerability, the attacker must convince a targeted user to connect to a malicious SMB server. An attacker could embed a connection request in a web page and convince the targeted user to visit that page. Attempts to exploit this vulnerability will likely require the use of social engineering tactics, such as sending a link to the site via e-mail, instant messaging, or other forms of communication.
Microsoft has released a security bulletin at the following link: MS10-020
Microsoft has released a security advisory at the following link: 977544
An unauthenticated, remote attacker could exploit this vulnerability to cause a DoS condition on the targeted system.
The vulnerability exists in the KeAccumulateTicks() function of the SMB client. The client fails to properly handle incomplete responses sent by a SMB server. An unauthenticated, remote attacker could create a malicious SMB or SMB2 server and convince the targeted user to connect to either server. If successful, the targeted user's system could stop responding to requests, leading to a DoS condition.
Administrators are advised to apply the appropriate updates.
Users are advised not to connect to untrusted SMB servers.
Users are advised not to open e-mail messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in e-mail messages are safe, they are advised not to open them.
Users should verify that unsolicited links are safe to follow.
Microsoft customers can obtain updates directly by using the links in the security bulletin. These updates are also distributed by Windows automatic update features and available on the Windows Update website. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
Version 3, April 13, 2010, 3:23 PM: Microsoft has released a security bulletin to address the Microsoft Windows SMB client remote denial of service vulnerability.
Version 2, November 16, 2009, 12:29 PM: Microsoft has released a security advisory that confirms the Microsoft Windows SMB client remote denial of service vulnerability.
Version 1, November 12, 2009, 1:53 PM: Microsoft Windows contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are not available.
Home Edition SP2, SP3 | Professional Edition SP2, SP3 | Professional x64 (AMD/EM64T) SP2
The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.