Remote Assistance invitation fails in an Active Directory environment in Windows 7 or in Windows Server 2008 R2

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this hotfix, you must be running one of the following operating systems:

• Windows 7 Service Pack 1 (SP1)
• Windows Server 2008 R2 Service Pack 1 (SP1)

For more information about how to obtain a Windows 7 or Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:

976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2

Registry information

To apply the hotfix in this package, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows 7 and Windows Server 2008 R2 file information notes

Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.

• The files that apply to a specific product, SR_Level (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table.

  Version	Product	SR_Level	Service branch
  6.1.760 1. 21xxx	Windows 7 and Windows Server 2008 R2	SP1	LDR

• The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows Server 2008 R2 and for Windows 7" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

For all supported x86-based versions of Windows 7

For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

For all supported IA-64–based versions of Windows Server 2008 R2

To identify this issue, you can use a network trace by enabling Net logon debug logging on the authenticating domain controller in domain B. For more information about how to do this, click the following article number to view the article in the Microsoft Knowledge Base:Notes

• The computer that offers remote assistance is typically called the "Expert."
• The computer that receives the remote assistance is typically called the "Novice."

1. A network trace that is taken from the client computer that offers remote assistance during the problem resembles the following:
   Remote procedure call (RPC) bind request with Kerberos service ticket from Expert to Novice:

   MSRPC MSRPC:c/o Alter Cont: unknown UUID{00000001-0000-0000-C000-000000000046} Call=0x2 Kerberos: AP Request Ticket[Realm: child.domainA.COM, Sname: <novice user>] 

   Novice to Expert response:

   MSRPC MSRPC:c/o Fault: Call=0x2 Context=0x0 Status=0x721 Cancels=0x0 {MSRPC:125, TCP:122, IPv4:117}

   The status of 0x721 = RPC_S_SEC_PACKAGE_ERROR
   
   "A security package specific error occurred" in other words a Kerberos error occurred.
   
   To view a complete list of RPC return codes, visit the following Microsoft TechNet website:
   http://technet.microsoft.com/en-us/library/aa378645(v=VS.85).aspx
2. A netlogon.log from the authenticating domain controller (that is, the domain controller that the Novice uses for authentication) in domain B will show the following Privilege Attribute Certificate (PAC) verification request failure:

   [LOGON] RESOURCE: SamLogon: Generic logon of child.DomainA.COM\(null) from (null) (via RESOURCE-WIN73) Package:Kerberos Entered 
   [LOGON] RESOURCE: SamLogon: Generic logon of EMEACHILD.LINDOM.COM\(null) from (null) (via RESOURCE-WIN73) Package:Kerberos Returns 0xC0000064

   0xc0000064 = STATUS_NO_SUCH_USER
   
   Important If you encounter this problem, you may have to do configuration changes to make Remote Assistance work across forests. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
   2682075 Configuring Remote Assistance to work across forests