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Microsoft Security Bulletin MS13-104 - Important

Vulnerability in Microsoft Office Could Allow Information Disclosure (2909976)

Published: December 10, 2013

Version: 1.0

General Information

Executive Summary

This security update resolves one privately reported vulnerabilityin Microsoft Office that could allow information disclosure if a user attempts to open an Office file hosted on a malicious website. An attacker who successfully exploited this vulnerability could ascertain access tokens used to authenticate the current user on a targeted SharePoint or other Microsoft Office server site.

This security update is rated Important for supported editions of Microsoft Office 2013 and Microsoft Office 2013 RT 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 Microsoft Office software properly handles specially crafted responses from websites. 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

Knowledge Base Article 2909976
File informationYes
SHA1/SHA2 hashesYes
Known issuesNone

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

Microsoft Office Suite and Other SoftwareMaximum Security ImpactAggregate Severity RatingUpdates Replaced
Microsoft Office 2013 and Microsoft Office 2013 RT
Microsoft Office 2013 (32-bit editions)
(2850064)
Information DisclosureImportantNone
Microsoft Office 2013 (64-bit editions)
(2850064)
Information DisclosureImportantNone
Microsoft Office 2013 RT[1]
(2850064)
Information DisclosureImportantNone

[1]This update is available via Windows Update.

 

Non-Affected Software 

Office and Other Software
Microsoft Office 2003 Service Pack 3
Microsoft Office 2007 Service Pack 3
Microsoft Office 2010 Service Pack 1 (32-bit editions)
Microsoft Office 2010 Service Pack 2 (32-bit editions)
Microsoft Office 2010 Service Pack 1 (64-bit editions)
Microsoft Office 2010 Service Pack 2 (64-bit editions)
Microsoft Office Compatibility Pack Service Pack 3
Microsoft Office for Mac 2011

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 2013 products, only Microsoft Office 2013 may be specifically listed in the Affected Software table. However, the update could apply to Microsoft Word 2013, Microsoft Excel 2013, Microsoft Visio 2013, or any other Microsoft Office 2013 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

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.

Affected SoftwareToken Hijacking Vulnerability - CVE-2013-5054Aggregate Severity Rating
Microsoft Office 2013 and Microsoft Office 2013 RT
Microsoft Office 2013 (32-bit editions) Important 
Information Disclosure
Important
Microsoft Office 2013 (64-bit editions) Important 
Information Disclosure
Important
Microsoft Office 2013 RT Important 
Information Disclosure
Important

An information disclosure vulnerability exists when affected Microsoft Office software does not properly handle a specially crafted response while attempting to open an Office file hosted on the malicious website. An attacker who successfully exploited this vulnerability could ascertain access tokens used to authenticate the current user on a targeted SharePoint or other Microsoft Office server site.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2013-5054.

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 or click a link contained inside 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 an information disclosure vulnerability. An attacker who successfully exploited this vulnerability could ascertain certain access tokens used to authenticate the current user on a targeted SharePoint or other Microsoft Office server site.

What causes the vulnerability? 
The vulnerability is caused when affected Microsoft Office software improperly handles specially crafted responses while attempting to open an Office file hosted on a malicious website.

What is an access token ? 
An access token is an object that describes the security context of a process or thread. The information in a token includes the identity and privileges of the user account associated with the process or thread. When a user logs on, the system verifies the user's password by comparing it with information stored in a security database. If the password is authenticated, the system produces an access token.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited this vulnerability could ascertain certain access tokens used to authenticate the current user on a targeted SharePoint or other Microsoft Office server site.

Note that an attacker could attempt to use the information disclosed by this vulnerability to leverage a replay attack against a targeted SharePoint or other Microsoft Office server site. For example, a user is tricked into clicking a link to open an Office file hosted on a malicious website. Exploiting this vulnerability, the malicious website could use a specially crafted response to ascertain the user's access token that is used to authenticate to a specific SharePoint site. An attacker could then retransmit the access token to the specific SharePoint site in an attempt to impersonate the user. An attacker who successfully impersonates the user could then take actions on behalf of the user on the targeted site.

How could an attacker exploit the vulnerability? 
Exploitation of this vulnerability requires that a user attempts to open an Office file hosted on a malicious website using an affected version of Microsoft Office software.

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. 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. For example, an attacker could trick users into clicking a link that attempts to open an Office file hosted on the attacker's website.

What systems are primarily at risk from the vulnerability? 
Systems such as workstations and terminal servers where Microsoft Office software is used 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.

What does the update do? 
The update addresses the vulnerability by helping to ensure that Microsoft Office software properly handles specially crafted responses from websites.

When this security bulletin was issued, had this vulnerability been publicly disclosed? 
No. Microsoft received information about this vulnerability through coordinated vulnerability disclosure.

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

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

Affected Software

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

Microsoft Office 2013 (all editions)

Reference Table

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

Security update file name For Microsoft Office 2013 (32-bit editions):
msoloc2013-kb2850064-fullfile-x86-glb.exe
For Microsoft Office 2013 (64-bit editions):
msoloc2013-kb2850064-fullfile-x64-glb.exe
Installation switches See Microsoft Knowledge Base Article 912203
Restart requirement In some cases, this update does not require a restart. If the required files are being used, this update will require a restart. If this behavior occurs, a message appears that advises you to restart.

To help reduce the chance that a restart will be required, stop all affected services and close all applications that may use the affected files prior to installing the security update. For more information about the reasons why you may be prompted to restart, see Microsoft Knowledge Base Article 887012.
Removal information Use Add or Remove Programs item in Control Panel.
File information See Microsoft Knowledge Base Article 2850064
Registry key verification Not applicable

Microsoft Office 2013 RT (all editions)

Reference Table

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

Deployment This update is available via Windows Update.
Restart requirement In some cases, this update does not require a restart. If the required files are being used, this update will require a restart. If this behavior occurs, a message appears that advises you to restart.

To help reduce the chance that a restart will be required, stop all affected services and close all applications that may use the affected files prior to installing the security update. For more information about the reasons why you may be prompted to restart, see Microsoft Knowledge Base Article 887012.
Removal information Click Control Panel, click System and Security, click Windows Update, and then under See also, click Installed updates and select from the list of updates.
File information See Microsoft Knowledge Base Article 2850064

Other Information

Acknowledgments

Microsoft thanks the following for working with us to help protect customers:

  • Noam Liran of Adallom for reporting the Token Hijacking Vulnerability (CVE-2013-5054)

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

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.

Built at 2014-04-18T13:49:36Z-07:00

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