Microsoft Security Bulletin MS15-050 - Important

Published: May 12, 2015

Version: 1.0

This security update resolves a vulnerability in Windows Service Control Manager (SCM), which is caused when SCM improperly verifies impersonation levels. The vulnerability could allow elevation of privilege if an attacker can first log on to the system and then run a specially crafted application designed to increase privileges.

This security update is rated Important for all supported editions of Microsoft Windows. For more information, see the Affected Software section.

The security update addresses the vulnerability by correcting the way that the SCM verifies impersonation levels. For more information about the vulnerability, see the Vulnerability Information section.

For more information about this update, see Microsoft Knowledge Base Article 3055642.

The following software versions or editions are affected. Versions or editions that are not listed are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, see Microsoft Support Lifecycle.

^[1]Windows Server 2003 is affected, but an update is not being issued for it. See the Update FAQ for more information.

^[2]This update is available via Windows Update only.

Windows Server 2003 is listed as an affected product; why is Microsoft not issuing an update for it?
Although Windows Server 2003 is an affected product, Microsoft is not issuing an update for it because the comprehensive architectural changes required would jeopardize system stability and cause application compatibility problems. Microsoft recommends that security-conscious customers upgrade to a later operating system in order to keep pace with the changing security threat landscape and benefit from the more robust protections that later operating systems provide.

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the May bulletin summary.

An elevation of privilege vulnerability exists in the Windows Service Control Manager (SCM) when the SCM improperly verifies impersonation levels. An attacker who successfully exploited this vulnerability could gain elevated privileges and make calls to SCM for which they lack sufficient privilege. The update addresses the vulnerability by correcting the way that the SCM verifies impersonation levels.

To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application designed to increase privileges. Workstations and terminal servers are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this to occur.

Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was originally issued Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers.

Microsoft has not identified any mitigating factors for this vulnerability.

Microsoft has not identified any workarounds for this vulnerability.

For Security Update Deployment information, see the Microsoft Knowledge Base article referenced in the Executive Summary.

Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgments for more information.

The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

• V1.0 (May 12, 2015): Bulletin published.

Page generated 2015-09-16 9:54Z-07:00.