Security Bulletin

Microsoft Security Bulletin MS13-106 - Important

Vulnerability in a Microsoft Office Shared Component Could Allow Security Feature Bypass (2905238)

Published: December 10, 2013

Version: 1.0

General Information

Executive Summary

This security update resolves one publicly disclosed vulnerability****in a Microsoft Office shared component that is currently being exploited. The vulnerability could allow security feature bypass if a user views a specially crafted webpage in a web browser capable of instantiating COM components, such as Internet Explorer. In a web-browsing attack scenario, an attacker who successfully exploited this vulnerability could bypass the Address Space Layout Randomization (ASLR) security feature, which helps protect users from a broad class of vulnerabilities. The security feature bypass by itself does not allow arbitrary code execution. However, an attacker could use this ASLR bypass vulnerability in conjunction with another vulnerability, such as a remote code execution vulnerability that could take advantage of the ASLR bypass to run arbitrary code.

This security update is rated Important for supported editions of Microsoft Office 2007 and Microsoft Office 2010 software. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by helping to ensure that the Microsoft Office shared component properly implements ASLR. For more information about the vulnerabilities, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

Recommendation. Customers can configure automatic updating to check online for updates from Microsoft Update by using the Microsoft Update service. Customers who have automatic updating enabled and configured to check online for updates from Microsoft Update typically 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 from Microsoft Update 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.

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

Knowledge Base Article

Affected and Non-Affected Software

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

Affected Software

Non-Affected Software 

Update FAQ

I am being offered this update for software I do not have installed on my system. Why am I being offered this update?
Due to the servicing model for Microsoft Office updates, you may be offered updates for software that you do not have installed on your system. For example, you may be offered an update for a Microsoft Office product even though you do not have the specific Office product installed. For more information on this behavior and recommended actions, see Microsoft Knowledge Base Article 830335.

I am being offered this update for software that is not specifically listed in the Affected Software table. Why am I being offered this update?
When updates address vulnerable code that exists in a component that is shared between multiple Microsoft Office products or shared between multiple versions of the same Microsoft Office product, the update is considered to be applicable to all supported products and versions that contain the vulnerable component.

For example, when an update applies to Microsoft Office 2007 products, only Microsoft Office 2007 may be specifically listed in the Affected Software table. However, the update could apply to Microsoft Word 2007, Microsoft Excel 2007, Microsoft Visio 2007, Microsoft Compatibility Pack, Microsoft Excel Viewer, or any other Microsoft Office 2007 product that is not specifically listed in the Affected Software table.

For example, when an update applies to Microsoft Office 2010 products, only Microsoft Office 2010 may be specifically listed in the Affected Software table. However, the update could apply to Microsoft Word 2010, Microsoft Excel 2010, Microsoft Visio 2010, Microsoft Visio Viewer, or any other Microsoft Office 2010 product that is not specifically listed in the Affected Software table.

For more information on this behavior and recommended actions, see Microsoft Knowledge Base Article 830335. For a list of Microsoft Office products an update may apply to, refer to the Microsoft Knowledge Base Article associated with the specific update.

I am being offered this update for software that is not vulnerable. Why am I being offered this update?
In some cases, an update may apply to Microsoft Office products that are specifically listed in the Non-Affected Software table or that are otherwise listed in the Affected Software table with "Not applicable" for security impact. For example, you may be offered a Microsoft Office security update even though this security bulletin indicates that the Office products or the version of the Office products that you do have installed are not affected. For more information on this behavior, see Microsoft Knowledge Base Article 830335.

Although updates may be available for the non-vulnerable software, users who choose not to apply these updates will not increase the security risk for their system. However, Microsoft recommends that users install all updates offered to their systems. This helps to maintain consistency for shared files across Office products. In some cases, an update to non-vulnerable software detects that the files on your system are already up-to-date and as a result, the update does not need to install files.

Does the offer to update a non-vulnerable version of Microsoft Office software constitute an issue in the servicing model for Microsoft Office updates?
No. The servicing model is based on how the update applies to shared components of Microsoft Office software. Some of the products offered an update may not access the vulnerable code, and thus the software is not affected by the vulnerability. However, the update mechanism is functioning correctly in that it detects a product version for applicable software on the system that is within the range of product versions that the update applies to, and thus offers the update. This helps to maintain consistency for shared files across Office products.

I am using an older release of the software discussed in this security bulletin. What should I do?
The affected software listed in this bulletin has been tested to determine which releases are affected. Other releases are past their support life cycle. For more information about the product lifecycle, see the Microsoft Support Lifecycle website.

It should be a priority for customers who have older releases of the software to migrate to supported releases to prevent potential exposure to vulnerabilities. To determine the support lifecycle for your software release, see Select a Product for Lifecycle Information. For more information about service packs for these software releases, see Service Pack Lifecycle Support Policy.

Customers who require custom support for older software must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, see the Microsoft Worldwide Information website, select the country in the Contact Information list, and then click Go to see a list of telephone numbers. When you call, ask to speak with the local Premier Support sales manager. For more information, see the Microsoft Support Lifecycle Policy FAQ.

Vulnerability Information

Severity Ratings and Vulnerability Identifiers

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 December bulletin summary. For more information, see Microsoft Exploitability Index.

HXDS ASLR Vulnerability - CVE-2013-5057

A security feature bypass exists in an Office shared component that does not properly implement Address Space Layout Randomization (ASLR). The vulnerability could allow an attacker to bypass the ASLR security feature, after which the attacker could load additional malicious code in the process in an attempt to exploit another vulnerability.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2013-5057.

Mitigating Factors

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:

• The vulnerability cannot be exploited automatically through email. For an attack to be successful a user must open an attachment that is sent in an email message.
• In a web-based attack scenario, an attacker could host a website that is used to attempt to exploit this vulnerability. In addition, compromised websites and websites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to view attacker controlled content. Instead, an attacker would have to convince users to take action, typically by getting them to click a link in an email message or Instant Messenger message that takes users to the attacker’s website.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

FAQ

What is the scope of the vulnerability?
This is a security feature bypass vulnerability.

What causes the vulnerability?
The vulnerability exists because a specific Microsoft Office shared component was not built to implement the ASLR security feature. As a result, an attacker can more reliably predict memory offsets of specific instructions in a given call stack.

Note Although the vulnerable Microsoft Office shared component is delivered with Microsoft Office products, it can be loaded in other applications, such as Internet Explorer.

What is ASLR?
Address Space Layout Randomization (ASLR) moves executable images into random locations when a system boots, which helps prevent an attacker from leveraging data at predictable locations. For a component to support ASLR, all components that it loads must also support ASLR. For example, if A.exe consumes B.dll and C.dll, all three must support ASLR. By default, Windows Vista, Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows 8, Windows 8.1, Windows RT, Windows RT 8.1, Windows Server 2012, and Windows Server 2012 R2 will randomize system DLLs and EXEs, but DLLs and EXEs created by Independent Software Vendors (ISVs) must opt in to support ASLR using the /DYNAMICBASE linker option.

ASLR also randomizes heap and stack memory:

• When an application creates a heap in Windows Vista, Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows 8, Windows 8.1, Windows RT, Windows RT 8.1, Windows Server 2012, and Windows Server 2012 R2, the heap manager will create that heap at a random location to help reduce the chance that an attempt to exploit a heap-based buffer overrun succeeds. Heap randomization is enabled by default for all applications running on Windows Vista and later.
• When a thread starts in a process linked with /DYNAMICBASE, Windows Vista, Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows 8, Windows 8.1, Windows RT, Windows RT 8.1, Windows Server 2012, and Windows Server 2012 R2 move the thread's stack to a random location to help reduce the chance that a stack-based buffer overrun exploit will succeed.

What might an attacker use the vulnerability to do?
In a web-browsing attack scenario, an attacker who successfully exploited this vulnerability could bypass the ASLR security feature, which protects users from a broad class of vulnerabilities. The security feature bypass by itself does not allow arbitrary code execution. However, an attacker could use this ASLR bypass vulnerability in conjunction with another vulnerability, such as a remote code execution vulnerability that could take advantage of the ASLR bypass to run arbitrary code.

How could an attacker exploit the vulnerability?
In a web-based attack scenario, an attacker could host a website that is used to attempt to exploit this vulnerability. In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted website. Instead, an attacker would have to convince users to take action. For example, an attacker could trick users into clicking a link that takes them to the attacker's site.

When a user visits a website that contains malicious content using a web browser capable of instantiating COM components, such as Internet Explorer, the affected Microsoft Office shared component can be loaded to bypass ASLR.

An attacker could tie this security feature bypass vulnerability to an additional vulnerability, usually a remote code execution vulnerability. The additional vulnerability would take advantage of the security feature bypass for exploitation. For example, a remote code execution vulnerability that is blocked by ASLR, could be exploited after a successful ASLR bypass.

What systems are primarily at risk from the vulnerability?
In the web-browsing scenario, successful exploitation of this vulnerability requires that a user is logged on and is visiting websites using a web browser capable of instantiating COM components. Therefore, any systems where a web browser is used frequently, such as workstations or terminal servers, are at the most risk from this vulnerability. Servers could be at more risk if administrators allow users to browse and read email on servers. However, best practices strongly discourage allowing this.

What does the update do?
The update addresses the vulnerability by helping to ensure that the Microsoft Office shared component properly implements ASLR.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
Yes. This vulnerability has been publicly disclosed. It has been assigned Common Vulnerability and Exposure number CVE-2013-5057.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?
Yes. Microsoft is aware of limited, targeted attacks that attempt to exploit this vulnerability.

Update Information

Detection and Deployment Tools and Guidance

Several resources are available to help administrators deploy security updates. 

• Microsoft Baseline Security Analyzer (MBSA) lets administrators scan local and remote systems for missing security updates and common security misconfigurations. 
• Windows Server Update Services (WSUS), Systems Management Server (SMS), and System Center Configuration Manager help administrators distribute security updates. 
• The Update Compatibility Evaluator components included with Application Compatibility Toolkit aid in streamlining the testing and validation of Windows updates against installed applications. 

For more information about these tools and guidance in deploying security updates across networks, see Security Tools for IT Pros. 

Security Update Deployment

Affected Software

For information about the specific security update for your affected software, click the appropriate link:

Microsoft Office 2007 (all editions)

Reference Table

The following table contains the security update information for this software.

Microsoft Office 2010 (all editions)

Reference Table

The following table contains the security update information for this software.

Other Information

Microsoft Active Protections Program (MAPP)

To improve security protections for customers, Microsoft provides vulnerability information to major security software providers in advance of each monthly security update release. Security software providers can then use this vulnerability information to provide updated protections to customers via their security software or devices, such as antivirus, network-based intrusion detection systems, or host-based intrusion prevention systems. To determine whether active protections are available from security software providers, please go to the active protections websites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners.

Support

How to obtain help and support for this security update

• Help installing updates: Support for Microsoft Update
• Security solutions for IT professionals: TechNet Security Troubleshooting and Support
• Help protect your computer that is running Windows from viruses and malware: Virus Solution and Security Center
• Local support according to your country: International Support

Disclaimer

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.

Revisions

• V1.0 (December 10, 2013): Bulletin published.

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