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             AUSCERT External Security Bulletin Redistribution

           MS15-052: Vulnerability in Windows Kernel Could Allow
                     Security Feature Bypass (3050514)
                                13 May 2015


        AusCERT Security Bulletin Summary

Product:           Microsoft Windows
Publisher:         Microsoft
Operating System:  Windows
Impact/Access:     Reduced Security -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2015-1674  

Original Bulletin: 

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MS15-052: Vulnerability in Windows Kernel Could Allow Security Feature Bypass

Bulletin Number: MS15-052

Bulletin Title: Vulnerability in Windows Kernel Could Allow Security Feature 

Severity: Important

KB Article: 3050514

Version: 1.0

Published Date: May 12, 2015

Executive Summary

This security update resolves a vulnerability in Microsoft Windows. The 
vulnerability could allow security feature bypass if an attacker logs on to an
affected system and runs a specially crafted application.

This security update is rated Important for supported editions of Windows 8, 
Windows Server 2012, Windows 8.1, and Windows Server 2012 R2. For more 
information, see the Affected Software section.

Affected Software

Windows 8 for 32-bit Systems

Windows 8 for x64-based Systems

Windows 8.1 for 32-bit Systems

Windows 8.1 for x64-based Systems

Windows Server 2012

Windows Server 2012 R2

Windows RT[1]

Windows RT 8.1[1]

Windows RT[1]

Windows RT 8.1[1]

[1]This update is available via Windows Update only.

Vulnerability Information

Windows Kernel Security Feature Bypass Vulnerability - CVE-2015-1674

A security feature bypass vulnerability exists when the Windows kernel fails 
to properly validate which mode the request comes from, allowing an attacker 
to retrieve information that could lead to a Kernel Address Space Layout 
Randomization (KASLR) bypass. An attacker who successfully exploited this 
vulnerability can then retrieve the base address of cng.sys from a compromised

To exploit this vulnerability, an attacker would have to log on to an affected
system and run a specially crafted application.

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.

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