Microsoft Security Bulletin MS14-055 - Important

Vulnerabilities in Microsoft Lync Server Could Allow Denial of Service (2990928)

Published: September 9, 2014 | Updated: September 23, 2014

Version: 3.0

General Information

Executive Summary

This security update resolves three privately reported vulnerabilities in Microsoft Lync Server. The most severe of these vulnerabilities could allow denial of service if an attacker sends a specially crafted request to a Lync server.

This security update is rated Important for all supported editions of Microsoft Lync Server 2010 and Microsoft Lync Server 2013. For more information, see the Affected and Non-Affected Software section.

The security update addresses the vulnerabilities by correcting the way Lync Server sanitizes user input and by correcting the way Lync Server handles exceptions and null dereferences. For more information about these vulnerabilities, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability 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 (including customers who have not enabled automatic updating), 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. The updates are also available via the download links in the Affected Software table later in this bulletin.

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

Knowledge Base Article

  • Knowledge Base Article: 2990928
  • File Information: Yes
  • SHA1/SHA2 hashes: Yes
  • Known issues: Yes

 

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 

Software

Maximum Security Impact

Aggregate Severity Rating

Updates Replaced

Microsoft Lync Server 2010

Microsoft Lync Server 2010
(Server)
(2982385)

None

No severity rating[1]

None

Microsoft Lync Server 2010
(Response Group Service)
(2982388)

Denial of Service

Important

None

Microsoft Lync Server 2013

Microsoft Lync Server 2013
(Server)
(2986072)

Denial of Service

Important

None

Microsoft Lync Server 2013
(Response Group Service)
(2982389)

Denial of Service

Important

None

Microsoft Lync Server 2013
(Core Components)
(2992965)

Denial of Service

Important

None

Microsoft Lync Server 2013
(Web Components Server)
(2982390)

Information Disclosure

Important

2963288 in MS14-032

[1]Severity ratings do not apply to this update for the specified software; however, as a defense-in-depth measure, Microsoft recommends that customers of this software apply this security update to help protect against any possible new attack vectors identified in the future.

 

Non-Affected Software

Communication Platforms and Software

Microsoft Communicator 2005

Microsoft Communicator 2005 Web Access

Microsoft Communicator 2007

Microsoft Communicator 2007 Web Access

Microsoft Communications Server 2007

Microsoft Communications Server 2007 Speech Server

Microsoft Communications Server 2007 R2

Microsoft Communicator 2007 R2

Microsoft Communicator 2007 R2 Attendant

Microsoft Communicator 2007 R2 Group Chat Admin

Microsoft Communicator 2007 R2 Group Chat Client

Microsoft Live Meeting 2007 Console

Microsoft Communicator for Mac 2011

Microsoft Communicator Mobile

Microsoft Communicator Phone Edition

Microsoft Lync 2010 (32-bit)

Microsoft Lync 2010 (64-bit)

Microsoft Lync 2010 Attendee (admin level install)

Microsoft Lync 2010 Attendee (user level install)

Microsoft Lync 2010 Attendant (32-bit)

Microsoft Lync 2010 Attendant (64-bit)

Microsoft Lync 2010 Group Chat

Microsoft Lync Server 2010 Group Chat Software Development Kit

Microsoft Lync for Mac 2011

Microsoft Lync 2013 (32-bit)

Microsoft Lync Basic 2013 (32-bit)

Microsoft Lync 2013 (64-bit)

Microsoft Lync Basic 2013 (64-bit)

 

Why was this bulletin revised on September 23, 2014? 
Microsoft rereleased this bulletin to announce the reoffering of the 2982385 security update file (server.msp) for Microsoft Lync Server 2010. The rereleased update addresses an issue in the original offering that prevented users from successfully installing the server.msp file. Customers who attempted to install the original update will be reoffered the 2982385 update and are encouraged to apply it at the earliest opportunity.

Why was this bulletin revised on September 15, 2014? 
Microsoft revised this bulletin to address a known issue that prevented users from successfully installing security update 2982385 for Microsoft Lync Server 2010. Microsoft is investigating behavior associated with the installation of this update, and will update this bulletin when more information becomes available. As an added precaution, Microsoft has removed the download links to the 2982385 security update.

For Microsoft Lync Server 2010 or Microsoft Lync Server 2013, are there any prerequisites for installing the updates listed in this bulletin? 
Yes. Before installing any updates for Microsoft Lync Server 2010 or Microsoft Lync Server 2013, the latest publicly released Cumulative Updates for Lync (or OCS) Server must be installed. Customers who have automatic updating enabled will not need to take any action because cumulative updates will be downloaded and installed automatically. Customers who manually test and install the standalone packages need to ensure that the latest publicly released updates are installed before installing the applicable updates for their system.

For more information, see:

Why does this update address several reported security vulnerabilities? 
This update contains support for several vulnerabilities because the modifications that are required to address these issues are located in related files.

Why are multiple update packages available for some affected software? 
The updates required to address the vulnerabilities described in this bulletin are offered across different update packages as indicated in the Affected Software table due to the componentized servicing model for Microsoft Lync software.

There are multiple update packages available for Microsoft Lync Server 2010 and Microsoft Lync Server 2013. Do I need to install all the updates listed in the Affected Software table for the software? 
Yes. Customers should apply all updates offered for the software installed on their systems.

Do I need to install these security updates in a particular sequence? 
No. Multiple updates for one version of Microsoft Lync Server software can be applied in any sequence.

Why am I not being offered all of the updates listed for the version of Microsoft Lync Server I am running on my system?
The updates listed for Microsoft Lync Server 2010 or Microsoft Lync Server 2013 will only be offered to systems that have the applicable component installed. For example, if you do not have the Response Group Service installed on your system, you will not be offered update 2982389 for Lync Server 2013 or update 2982388 for Lync Server 2010 respectively.

Does this update contain any additional security-related changes? 
Yes. In addition to the changes that are listed in the Vulnerability Information section of this bulletin, this update includes defense-in-depth updates to the Microsoft Lync Server to help improve security-related features.

What is defense-in-depth? 
In information security, defense-in-depth refers to an approach in which multiple layers of defense are in place to help prevent attackers from compromising the security of a network or system.

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.

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

Vulnerability Severity Rating and Maximum Security Impact by Affected Software

Affected Software

Lync Denial of Service Vulnerability - CVE-2014-4068

Lync XSS Information Disclosure Vulnerability - CVE-2014-4070

Lync Denial of Service Vulnerability - CVE-2014-4071

Aggregate Severity Rating

Microsoft Lync Server 2010
(Server)

No severity rating

No severity rating

No severity rating

No severity rating

Microsoft Lync Server 2010
(Response Group Service)

Important 
Denial of Service

Not applicable

Not applicable

Important

Microsoft Lync Server 2013
(Server)

Not applicable

Not applicable

Important 
Denial of Service

Important

Microsoft Lync Server 2013
(Response Group Service)

Important 
Denial of Service

Not applicable

Not applicable

Important

Microsoft Lync Server 2013
(Core Components)

Important 
Denial of Service

Not applicable

Not applicable

Important

Microsoft Lync Server 2013
(Web Components Server)

Not applicable

Important 
Information Disclosure

Not applicable

Important

 

A denial of service vulnerability exists in Lync Server. An attacker who successfully exploited this vulnerability could cause the affected system to stop responding.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2014-4068.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability

FAQ

What is the scope of the vulnerability? 
This is a denial of service vulnerability.

What causes the vulnerability? 
The vulnerability is caused when Lync Server improperly handles certain exceptions.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited the vulnerability could cause the target system to stop responding.

How could an attacker exploit the vulnerability? 
A remote, unauthenticated attacker could exploit this vulnerability by executing a specially crafted call to trigger the improperly handled exceptions.

What systems are primarily at risk from the vulnerability? 
Systems with affected editions of Microsoft Lync Server installed and the Lync clients that connect to them are at risk from this vulnerability.

What does the update do? 
The update addresses the vulnerability by correcting the way Lync Server handles exceptions.

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.

A reflected cross-site scripting (XSS) vulnerability, which could result in information disclosure, exists when Lync Server fails to properly sanitize specially crafted content. An attacker who successfully exploited this vulnerability could potentially execute scripts in the user’s browser to obtain information from web sessions.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2014-4070.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

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:

  • Read email messages in plain text

    To help protect yourself from the email attack vector, read email messages in plain text format.

    Microsoft Outlook 2013 and Microsoft Outlook 2010 users can enable this setting and view email messages that are not digitally signed or email messages that are not encrypted in plain text only. Digitally signed email messages or encrypted email messages are not affected by the setting and may be read in their original formats; however, users can also elect to view these messages in plain text. For more information about how to enable this setting see:

 

Impact of workaround. Email messages that are viewed in plain text format will not contain pictures, specialized fonts, animations, or other rich content.

Additionally:

  • The changes are applied to the preview pane and to open messages.
  • Pictures become attachments so that they are not lost.
  • Because the message is still in Rich Text or HTML format in the store, the object model (custom code solutions) may behave unexpectedly.

 

  • Set Internet and Local intranet security zone settings to "High" to block ActiveX Controls and Active Scripting in these zones

    You can help protect against exploitation of these vulnerabilities by changing your settings for the Internet security zone to block ActiveX controls and Active Scripting. You can do this by setting your browser security to High.

    To raise the browsing security level in Internet Explorer, perform the following steps:

    1. On the Internet Explorer Tools menu, click Internet Options.
    2. In the Internet Options dialog box, click the Security tab, and then click Internet.
    3. Under Security level for this zone, move the slider to High. This sets the security level for all websites you visit to High.
    4. Click Local intranet.
    5. Under Security level for this zone, move the slider to High. This sets the security level for all websites you visit to High.
    6. Click OK to accept the changes and return to Internet Explorer.

     

    Note If no slider is visible, click Default Level, and then move the slider to High.

    Note Setting the level to High may cause some websites to work incorrectly. If you have difficulty using a website after you change this setting, and you are sure the site is safe to use, you can add that site to your list of trusted sites. This will allow the site to work correctly even with the security setting set to High.

    Impact of workaround. There are side effects to blocking ActiveX Controls and Active Scripting. Many websites that are on the Internet or on an intranet use ActiveX or Active Scripting to provide additional functionality. For example, an online e-commerce site or banking site may use ActiveX Controls to provide menus, ordering forms, or even account statements. Blocking ActiveX Controls or Active Scripting is a global setting that affects all Internet and intranet sites. If you do not want to block ActiveX Controls or Active Scripting for such sites, use the steps outlined in "Add sites that you trust to the Internet Explorer Trusted sites zone".

    Add sites that you trust to the Internet Explorer Trusted sites zone

    After you set Internet Explorer to block ActiveX controls and Active Scripting in the Internet zone and in the Local intranet zone, you can add sites that you trust to the Internet Explorer Trusted sites zone. This will allow you to continue to use trusted websites exactly as you do today, while helping to protect yourself from this attack on untrusted sites. We recommend that you add only sites that you trust to the Trusted sites zone.

    To do this, perform the following steps:

    1. In Internet Explorer, click Tools, click Internet Options, and then click the Security tab.
    2. In the Select a web content zone to specify its current security settings box, click Trusted Sites, and then click Sites.
    3. If you want to add sites that do not require an encrypted channel, click to clear the Require server verification (https:) for all sites in this zone check box.
    4. In the Add this website to the zone box, type the URL of a site that you trust, and then click Add.
    5. Repeat these steps for each site that you want to add to the zone.
    6. Click OK two times to accept the changes and return to Internet Explorer.

     

    Note Add any sites that you trust not to take malicious action on your system. Two in particular that you may want to add are *.windowsupdate.microsoft.com and *.update.microsoft.com. These are the sites that will host the update, and it requires an ActiveX Control to install the update.

FAQ

What is the scope of the vulnerability? 
This is an information disclosure vulnerability.

What causes the vulnerability? 
The vulnerability is caused when Lync Server does not properly sanitize specially crafted content.

What is cross-site scripting? 
Cross-site scripting (XSS) is a class of security vulnerability that can enable an attacker to inject script code into a user's session with a website. The vulnerability can affect web servers that dynamically generate HTML pages. If these servers embed browser input in the dynamic pages that they send back to the bowser, these servers can be manipulated to include maliciously supplied content in the dynamic pages. This can allow malicious script to be executed. Web browsers may perpetuate this problem through their assumptions of trusted sites and their use of cookies to maintain persistent state with the websites that they frequent. An XSS attack does not modify website content. Instead, it inserts new, malicious script that can execute at the browser in the context that is associated with a trusted server.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited this vulnerability could potentially execute scripts in the user’s browser to obtain information from web sessions.

How could an attacker exploit the vulnerability? 
For this vulnerability to be exploited, a user must click a specially crafted URL.

In an email attack scenario, an attacker could exploit the vulnerability by sending an email message containing the specially crafted URL to the user and by convincing the user to click on the specially crafted URL.

In a web-based attack scenario, an attacker would have to host a website that contains a specially crafted URL. 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 them to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes them to the attacker's website, and then convince them to click on the specially crafted URL.

What systems are primarily at risk from the vulnerability? 
Systems with affected editions of Microsoft Lync Server installed and the Lync clients that connect to them are at risk from this vulnerability.

What does the update do? 
The update addresses the vulnerability by correcting the way Lync Server sanitizes user input.

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.

A denial of service vulnerability exists in Lync Server. An attacker who successfully exploited this vulnerability could cause the affected system to stop responding.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2014-4071.

Mitigating Factors

Microsoft has not identified any mitigating factors for this vulnerability.

Workarounds

Microsoft has not identified any workarounds for this vulnerability.

FAQ

What is the scope of the vulnerability? 
This is a denial of service vulnerability.

What causes the vulnerability? 
The vulnerability is caused when Lync Server improperly handles a null dereference.

What might an attacker use the vulnerability to do? 
An attacker who successfully exploited the vulnerability could cause the target system to stop responding.

How could an attacker exploit the vulnerability? 
A remote, unauthenticated attacker could exploit this vulnerability by sending a specially crafted request to a Lync server.

What systems are primarily at risk from the vulnerability? 
Systems with affected editions of Microsoft Lync Server installed and the Lync clients that connect to them are at risk from this vulnerability.

What does the update do? 
The update addresses the vulnerability by correcting the way in which Lync Server handles null dereferences.

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.

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 information about these and other tools that are available, see Security Tools for IT Pros

Microsoft Lync Server 2010

Reference Table

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

Security update file name

For Microsoft Lync Server 2010 (2982385):
server.msp


For Microsoft Lync Server 2010 (2982388):
rgs.msp

Installation switches

See Microsoft Knowledge Base Article 197147

Restart requirement

This update does not require a restart. The installer stops the required services, applies the update, and then restarts the services. However, if the required services cannot be stopped for any reason, or if required files are being used, this update will require a restart. If this behavior occurs, a message appears that advises you to restart.

Removal information

Use Add or Remove Programs item in Control Panel.

File information

See Microsoft Knowledge Base Article 2982385
See Microsoft Knowledge Base Article 2982388

Registry key verification

For Microsoft Lync Server 2010 (server.msp):
HKLM\Software\Microsoft\Real-Time Communications\{A593FD00-64F1-4288-A6F4-E699ED9DCA35}\Version = 4.0.7577.276


For Microsoft Lync Server 2010 (rgs.msp):
HKLM\Software\Microsoft\Real-Time Communications\{{11CFB169-07EA-489D-BF8C-D8D29525720E}\Version = 4.0.7577.276

 

Microsoft Lync Server 2013

Reference Table

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

Security update file name

For Microsoft Lync Server 2013 (2986072):
server.msp


For Microsoft Lync Server 2013 (2982389):
rgs.msp


For Microsoft Lync Server 2013 (2992965):
OCSCore.msp


For Microsoft Lync Server 2013 (2982390):
WebComponents.msp

Installation switches

See Microsoft Knowledge Base Article 197147

Restart requirement

This update does not require a restart. The installer stops the required services, applies the update, and then restarts the services. However, if the required services cannot be stopped for any reason, or if required files are being used, this update will require a restart. If this behavior occurs, a message appears that advises you to restart.

Removal information

Use Add or Remove Programs item in Control Panel.

File information

See Microsoft Knowledge Base Article 2986072
See Microsoft Knowledge Base Article 2982389
See Microsoft Knowledge Base Article 2992965
See Microsoft Knowledge Base Article 2982390

Registry key verification

For Microsoft Lync Server 2013 (server.msp):
HKLM\Software\Microsoft\Real-Time Communications\{A593FD00-64F1-4288-A6F4-E699ED9DCA35}\Version = 5.0.8308.803


For Microsoft Lync Server 2013 (rgs.msp):
HKLM\Software\Microsoft\Real-Time Communications\{11CFB169-07EA-489D-BF8C-D8D29525720E}\Version = 5.0.8308.803


For Microsoft Lync Server 2013 (OCSCore.msp):
HKLM\Software\Microsoft\Real-Time Communications\{A766C25B-A1D1-4711-A726-AC3E7CA4AAB3}\Version = 5.0.8308.803


For Microsoft Lync Server 2013 (WebComponents.msp):
HKLM\Software\Microsoft\Real-Time Communications\{2A65AB9C-57AD-4EC6-BD4E-BD61A7C583B3}\Version = 5.0.8308.803

 

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

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 (September 9, 2014): Bulletin published.
  • V2.0 (September 15, 2014): Bulletin revised to remove Download Center links for Microsoft security update 2982385 for Microsoft Lync Server 2010. See the Update FAQ for details.
  • V3.0 (September 23, 2014): Bulletin rereleased to announce the reoffering of the 2982385 security update file (server.msp) for Microsoft Lync Server 2010. See the Update FAQ for details.

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