Microsoft has updated security bulletin MS10-020 - Critical: Vulnerabilities in SMB Client Could Allow Remote Code Execution

Severity Rating: Critical - Revision Note: V1.1 (May 26, 2010): Added a link to Microsoft Knowledge Base Article 980232 under Known Issues in the Executive Summary.

Summary: This security update resolves one publicly disclosed and several privately reported vulnerabilities in Microsoft Windows. The vulnerabilities could allow remote code execution if an attacker sent a specially crafted SMB response to a client-initiated SMB request. To exploit these vulnerabilities, an attacker must convince the user to initiate an SMB connection to a specially crafted SMB server.

This security update is rated Critical for all supported editions of Microsoft Windows. For more information, see the subsection, Affected and Non-Affected Software, in this section.
The security update addresses the vulnerabilities by correcting the manner in which the SMB client handles SMB responses, allocates memory, and validates fields within the SMB response. For more information about the vulnerabilities, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

This security update also addresses the vulnerability first described in Microsoft Security Advisory 977544.

Recommendation. The majority of customers have automatic updating enabled and will not need to take any action because this security update will be downloaded and installed automatically. Customers who have not enabled automatic updating need to check for updates and install this update manually. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871.

For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update immediately using update management software, or by checking for updates using the Microsoft Update service.

See also the section, Detection and Deployment Tools and Guidance, later in this bulletin.

  MS10-020 - Critical: Vulnerabilities in SMB Client Could Allow Remote Code Execution (980232) - Version: 1.1