Vulnerabilities in Microsoft Office Could Allow Remote Code Execution (2961037)
Published: May 13, 2014 | Updated: May 13, 2014
Version: 1.1
General Information
Executive Summary
This security update resolves two privately reported vulnerabilities in Microsoft Office. The most severe vulnerability could allow remote code execution if a user opens an Office file that is located in the same network directory as a specially crafted library file. An attacker who successfully exploited this vulnerability could gain the same user rights as the current user. Customers whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.
This security update is rated Important for supported editions of Microsoft Office 2007, Microsoft Office 2010, and Microsoft Office 2013. For more information, see the Affected and Non-Affected Software section.
The security update addresses the vulnerabilities by helping to ensure that the Chinese (Simplified) Grammar Checker feature in Microsoft Office properly verifies file paths before loading external libraries and 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 later in this bulletin.
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.
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.
Microsoft Office Compatibility Pack Service Pack 3
Microsoft Office for Mac 2011
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, only systems that have the Chinese (Simplified) Grammar Checker are vulnerable to CVE-2014-1756. However, you may be offered the proofing tools update for your version of Microsoft Office even if you do not specifically have the Chinese (Simplified) Grammar Checker.
In addition, CVE-2014-1808 affects a shared component used by Microsoft Office 2013 software. The MSO update may be offered to systems running any affected Microsoft Office 2013 product that uses the shared component.
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.
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 May bulletin summary. For more information, see Microsoft Exploitability Index.
Vulnerability Severity Rating and Maximum Security Impact by Affected Software
Affected Software
Microsoft Office Chinese Grammar Checking Vulnerability - CVE-2014-1756
Token Reuse Vulnerability - CVE-2014-1808
Aggregate Severity Rating
Microsoft Office 2007
Microsoft Office 2007 Service Pack 3 (proofing tools) (Simplified Chinese only)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2010
Microsoft Office 2010 Service Pack 1 (32-bit editions) (proofing tools) (Simplified Chinese only)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2010 Service Pack 2 (32-bit editions) (proofing tools) (Simplified Chinese only)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2010 Service Pack 1 (64-bit editions) (proofing tools) (Simplified Chinese only)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2010 Service Pack 2 (64-bit editions) (proofing tools) (Simplified Chinese only)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2013 and Microsoft Office 2013 RT
Microsoft Office 2013 (32-bit editions) (proofing tools)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2013 Service Pack 1 (32-bit editions) (proofing tools)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2013 (32-bit editions) (mso)
Not applicable
Important Information Disclosure
Important
Microsoft Office 2013 Service Pack 1 (32-bit editions) (mso)
Not applicable
Important Information Disclosure
Important
Microsoft Office 2013 (64-bit editions) (proofing tools)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2013 Service Pack 1 (64-bit editions) (proofing tools)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2013 (64-bit editions) (mso)
Not applicable
Important Information Disclosure
Important
Microsoft Office 2013 Service Pack 1 (64-bit editions) (mso)
Not applicable
Important Information Disclosure
Important
Microsoft Office 2013 RT (proofing tools)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2013 RT Service Pack 1 (proofing tools)
Important Remote Code Execution
Not applicable
Important
Microsoft Office 2013 RT Service Pack 1 (mso)
Not applicable
Important Information Disclosure
Important
Microsoft Office 2013 RT (mso)
Not applicable
Important Information Disclosure
Important
Microsoft Office Chinese Grammar Checking Vulnerability - CVE-2014-1756
A remote code execution vulnerability exists in the way that affected Microsoft Office software handles the loading of dynamic-link library (.dll) files. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2014-1756.
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:
Only systems with the Grammar Checker for Chinese (Simplified) feature enabled in Microsoft Office are affected by the vulnerability.
For an attack to be successful in a network attack scenario, a user must visit an untrusted remote file system location or WebDAV share and open an Office-related file (such as a .docx file). The file sharing protocol, Server Message Block (SMB), is often disabled on the perimeter firewall. This limits the potential attack vectors for this vulnerability.
An attacker who successfully exploited this vulnerability could gain the same user rights as the current user. Customers whose accounts are configured to have fewer user rights on the system could be less impacted than those who operate with administrative user rights.
Workarounds
Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:
Disable loading of libraries from WebDAV and remote network shares
Note See Microsoft Knowledge Base Article 2264107 to deploy a workaround tool that allows customers to disable the loading of libraries from remote network or WebDAV shares. This tool can be configured to disallow insecure loading on a per-application or a global system basis.
Customers who are informed by their vendor of an application being vulnerable can use this tool to help protect against attempts to exploit this issue.
Note See Microsoft Knowledge Base Article 2264107 to use the automated Microsoft Fix it solution to deploy the registry key to block loading of libraries for SMB and WebDAV shares. Note that this Fix it solution does require you to install the workaround tool also described in Microsoft Knowledge Base Article 2264107 first. This Fix it solution only deploys the registry key and requires the workaround tool in order to be effective. We recommend that administrators review the KB article closely prior to deploying this Fix it solution.
Disable the WebClient service
Disabling the WebClient service helps protect affected systems from attempts to exploit this vulnerability by blocking the most likely remote attack vector through the Web Distributed Authoring and Versioning (WebDAV) client service. After applying this workaround it is still possible for remote attackers who successfully exploit this vulnerability to cause the system to run programs located on the targeted user's computer or the Local Area Network (LAN), but users will be prompted for confirmation before opening arbitrary programs from the Internet.
To disable the WebClient Service, follow these steps:
Click Start, click Run, type Services.msc and then click OK.
Right-click WebClient service and select Properties.
Change the Startup type to Disabled. If the service is running, click Stop.
Click OK and exit the management application.
Impact of workaround. When the WebClient service is disabled, Web Distributed Authoring and Versioning (WebDAV) requests are not transmitted. In addition, any services that explicitly depend on the Web Client service will not start, and an error message will be logged in the System log. For example, WebDAV shares will be inaccessible from the client computer.
How to undo the workaround.
To re-enable the WebClient Service, follow these steps:
Click Start, click Run, type Services.msc and then click OK.
Right-click WebClient service and select Properties.
Change the Startup type to Automatic. If the service is not running, click Start.
Click OK and exit the management application.
Block TCP ports 139 and 445 at the firewall
These ports are used to initiate a connection with the affected component. Blocking TCP ports 139 and 445 at the firewall will help protect systems that are behind that firewall from attempts to exploit this vulnerability. Microsoft recommends that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. For more information about ports, see the TechNet article, TCP and UDP Port Assignments.
Impact of workaround. Several Windows services use the affected ports. Blocking connectivity to the ports may cause various applications or services to not function. Some of the applications or services that could be impacted are listed below:
Applications that use SMB (CIFS)
Applications that use mailslots or named pipes (RPC over SMB)
Server (File and Print Sharing)
Group Policy
Net Logon
Distributed File System (DFS)
Terminal Server Licensing
Print Spooler
Computer Browser
Remote Procedure Call Locator
Fax Service
Indexing Service
Performance Logs and Alerts
Systems Management Server
License Logging Service
How to undo the workaround. Unblock TCP ports 139 and 445 at the firewall. For more information about ports, see TCP and UDP Port Assignments.
FAQ
What is the scope of the vulnerability?
This is a remote code execution vulnerability in the context of the current user.
What causes the vulnerability?
The vulnerability is caused when the Grammar Checker feature for Chinese (Simplified) in Microsoft Office does not properly validate the path used for loading external libraries.
What is the Grammar/Style Checker feature in Microsoft Office?
The Grammar/Style Checker feature is part of document-proofing tools enabled in Microsoft Office Language Pack Proofing Tools. Microsoft Office Language Pack Proofing Tools are available for specific languages, or as a complete set called the Office Multi-language Pack. For more information, see What's included in Office Language Pack Proofing Tools.
This vulnerability only affects systems with the Chinese (Simplified) Language Pack Proofing Tool installed.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could run arbitrary code in the context of the current user. If the current user is logged on with administrative user rights, an attacker could take complete control of the affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
How could an attacker exploit the vulnerability?
An attacker could convince a user to open an Office-related file (such as a .docx file) that is located in the same network directory as a specially crafted dynamic link library (.dll) file. Then, while opening the Office-related file, the Chinese Grammar Checker feature in Microsoft Office could attempt to load the .dll file and execute any code it contained.
In an email attack scenario, an attacker could exploit the vulnerability by sending an Office-related file attachment (such as a .docx file) to a user, and convincing the user to place the attachment into a directory containing a specially crafted .dll file and to open the legitimate file. Then, while opening the Office-related file, the Chinese Grammar Checker feature in Microsoft Office could attempt to load the .dll file and execute any code it contained.
In a network attack scenario, an attacker could place an Office-related file (such as a .docx file) and a specially crafted .dll file in a network share, a UNC, or WebDAV location and then convince the user to open the Office-related file.
What systems are primarily at risk from the vulnerability?
Systems where affected Microsoft Office software is used, including 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.
What does the update do?
This update addresses the vulnerability by helping to ensure that the Chinese (Simplified) Grammar Checker feature in Microsoft Office properly verifies file paths before loading external libraries.
Is this vulnerability related to Microsoft Security Advisory 2269637?
Yes, this vulnerability is related to the class of vulnerabilities, described in Microsoft Security Advisory 2269637, that affects how applications load external libraries. This security update addresses a particular instance of this type of vulnerability.
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?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.
Token Reuse Vulnerability - CVE-2014-1808
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 Microsoft online service.
To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2014-1808.
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 Microsoft online service.
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 Microsoft online service.
Note that an attacker could attempt to use the information disclosed by this vulnerability to leverage a replay attack against a targeted Microsoft online service. 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 Microsoft service. 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?
No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.
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.
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.
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.
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.
The following table contains the security update information for this software.
Deployment
The 2880463 and 2878316 updates for Microsoft Office 2013 RT are 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.
Microsoft thanks the following for working with us to help protect customers:
NSFOCUS Security Team for reporting the Microsoft Office Chinese Grammar Checking Vulnerability (CVE-2014-1756)
Arnaud Maillet from ANSSI for reporting the Token Reuse Vulnerability (CVE-2014-1808)
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
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 (May 13, 2014): Bulletin published.
V1.1 (May 13, 2014): Corrected the update replacement for the Microsoft Office 2010 (proofing tools) (2878284) update.
This module examines how Microsoft Defender for Office 365 extends EOP protection through various tools, including Safe Attachments, Safe Links, spoofed intelligence, spam filtering policies, and the Tenant Allow/Block List.