This security update resolves a privately reported vulnerability in Microsoft Windows. The vulnerability could allow elevation of privilege if an attacker spoofs an LRPC server and sends a specially crafted LPC port message to any LRPC client. An attacker who successfully exploited the vulnerability could then install programs; view, change, or delete data; or create new accounts with full administrator rights. An attacker must have valid logon credentials and be able to log on locally to exploit this vulnerability.
This security update is rated Important for all supported editions of Windows XP and Windows Server 2003. For more information, see the subsection, Affected and Non-Affected Software, in this section.
The security update addresses the vulnerability by validating LRPC messages. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.
Recommendation. Most 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 at the earliest opportunity using update management software, or by checking for updates using the Microsoft Update service.