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Microsoft Security Bulletin MS14-076 - Important

Vulnerability in Internet Information Services (IIS) Could Allow Security Feature Bypass (2982998)

Published: November 11, 2014 | Updated: December 19, 2014

Version: 1.1

This security update resolves a privately reported vulnerability in Microsoft Internet Information Services (IIS) that could lead to a bypass of the "IP and domain restrictions" security feature. Successful exploitation of this vulnerability could result in clients from restricted or blocked domains having access to restricted web resources.

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

The security update addresses the vulnerability by changing how IIS handles requests when specific IP and domain restriction configurations exist. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability.

For more information about this document, see Microsoft Knowledge Base Article 2982998

The following software has been tested to determine which versions or editions are affected. Other versions or editions either are 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.

Operating System

Component

Maximum Security Impact

Aggregate Severity Rating

Updates Replaced

Windows 8 and Windows 8.1

Windows 8 for 32-bit Systems

Microsoft Internet Information Services 8.0
(2982998)

Security Feature Bypass

Important

None

Windows 8 for x64-based Systems

Microsoft Internet Information Services 8.0
(2982998)

Security Feature Bypass

Important

None

Windows 8.1 for 32-bit Systems

Microsoft Internet Information Services 8.5
(2982998)

Security Feature Bypass

Important

None

Windows 8.1 for x64-based Systems

Microsoft Internet Information Services 8.5
(2982998)

Security Feature Bypass

Important

None

Windows Server 2012 and Windows Server 2012 R2

Windows Server 2012

Microsoft Internet Information Services 8.0
(2982998)

Security Feature Bypass

Important

None

Windows Server 2012 R2

Microsoft Internet Information Services 8.5
(2982998)

Security Feature Bypass

Important

None

Server Core installation option

Windows Server 2012 (Server Core installation)

Microsoft Internet Information Services 8.0
(2982998)

Security Feature Bypass

Important

None

Windows Server 2012 R2 (Server Core installation)

Microsoft Internet Information Services 8.5
(2982998)

Security Feature Bypass

Important

None

 

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 November bulletin summary.

Affected Software

IIS Security Feature Bypass Vulnerability - CVE-2014-4078

Aggregate Severity Rating

IIS 8.0 on Windows 8 for 32-bit Systems

Important 
Security Feature Bypass

Important

IIS 8.0 on Windows 8 for x64-based Systems

Important 
Security Feature Bypass

Important

IIS 8.5 on Windows 8.1 for 32-bit Systems

Important 
Security Feature Bypass

Important

IIS 8.5 on Windows 8.1 for x64-based Systems

Important 
Security Feature Bypass

Important

IIS 8.0 on Windows Server 2012 for x64-based Systems

Important 
Security Feature Bypass

Important

IIS 8.0 on Windows Server 2012 (Server Core Installation)

Important 
Security Feature Bypass

Important

IIS 8.5 on Windows Server 2012 R2 for x64-based Systems

Important 
Security Feature Bypass

Important

IIS 8.5 on Windows Server 2012 R2 (Server Core Installation)

Important 
Security Feature Bypass

Important

 

A security feature bypass vulnerability exists in Microsoft Information Services (IIS) that is caused when incoming web requests are not properly compared against the "IP and domain restriction" filtering list. Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was issued, Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers. The update addresses the vulnerability by modifying how inbound web requests are compared to the allow/deny list maintained by the "IP and domain restrictions" component. 

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

The following workarounds may be helpful in your situation:

FAQ

What is "IP and domain restrictions"? 
This is a feature provided in the "IP Security" sub-component of IIS that allows the creation of allow/deny lists to control access to web resources. For more information, see the article IP security.

Are there any prerequisites for the 2982998 update?
Yes. Customers must enable the feature "IP Security" sub-component of IIS on Windows clients, and/or enable the feature "IP and Domain Restrictions" on Windows servers as a prerequisite to be offered the security update.

What might an attacker use the vulnerability to do? 
If an IIS administrator created a wildcard domain restriction rule, an attacker from a denied domain could access a website that an IIS administrator believed was restricted.

How could an attacker exploit the vulnerability? 
To exploit this vulnerability, an attacker would require in depth knowledge of the remote IIS server and corresponding network topology. An attacker would also need to have control of their reverse DNS information, or be able to poison the authoritative DNS of the IIS server, in order to provide a domain name that is formatted in a manner that causes the vulnerability.

What systems are primarily at risk from the vulnerability? 
Windows systems with IIS that use “IP Address and Domain Restrictions,” and have specifically enabled the “Enable domain name restrictions” functionality are primarily at risk. 

For Security Update Deployment information, see the Microsoft Knowledge Base article referenced here 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 (November 11, 2014): Bulletin published.
  • V1.1 (December 19, 2014): Bulletin revised to include Windows 2012 Server Core installation and Windows 2012 R2 Server Core installation as affected software.

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