Symptoms

Consider the following scenario:

  • There is a forest trust established between two root domains (root domain A and root domain B) in an Active Directory environment.

  • There is a child domain in root domain A. For example, root domain A is child.domainA.com.

  • There is a client computer in root domain B that is running Windows 7 or Windows Server 2008 R2.

  • You are in the child domain in root domain A, and you log on to the computer in domain B.

  • You open a Remote Assistance invitation to connect to another user's computer. The other user is also in domain A and is logged on to a computer that is amember of domain B.

In this scenario, the Remote Assistance invitation fails. Additionally, you receive an error message that resembles the following:

Your offer to help could not be sent

Check the following:

Do you have the correct permissions on the remote computer?

Is the remote computer turns on, and is it connected to the network?

Is there a network problem?

For assistance, contact your network administrator.

Cause

This issue occurs because Privilege Attribute Certificate (PAC) validation fails across Active Directory forests.

Resolution

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:

http://support.microsoft.com/contactus/?ws=supportNote 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

File name

File version

File size

Date

Time

Kerberos.dll

6.1.7601.21932

542,208

29-Feb-2012

05:20

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

File name

File version

File size

Date

Time

Platform

Kerberos.dll

6.1.7601.21932

716,288

29-Feb-2012

06:20

x64

Kerberos.dll

6.1.7601.21932

542,208

29-Feb-2012

05:20

x86

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

File name

File version

File size

Date

Time

Platform

Kerberos.dll

6.1.7601.21932

1,500,160

29-Feb-2012

05:22

IA-64

Kerberos.dll

6.1.7601.21932

542,208

29-Feb-2012

05:20

x86

Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

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:

109626 Enabling debug logging for the Net Logon serviceNotes

  • 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

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Additional file information

Additional file information for Windows 7 and for Windows Server 2008 R2

Additional files for all supported x86-based versions of Windows 7

File name

X86_7cf403405c83884862a12c0d4c61113b_31bf3856ad364e35_6.1.7601.21932_none_cc95df321870270f.manifest

File version

Not applicable

File size

705

Date (UTC)

29-Feb-2012

Time (UTC)

21:06

File name

X86_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7601.21932_none_e9504928283f4576.manifest

File version

Not applicable

File size

33,218

Date (UTC)

29-Feb-2012

Time (UTC)

05:52

Additional files for all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

File name

Amd64_e04bb200be26752a5a170258778de12f_31bf3856ad364e35_6.1.7601.21932_none_6740d246eed88f0b.manifest

File version

Not applicable

File size

709

Date (UTC)

29-Feb-2012

Time (UTC)

21:06

File name

Amd64_e663cfdb66c1ec59b482f4e9ea63ac93_31bf3856ad364e35_6.1.7601.21932_none_baedcaa7c7d05b27.manifest

File version

Not applicable

File size

1,060

Date (UTC)

29-Feb-2012

Time (UTC)

21:06

File name

Amd64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7601.21932_none_456ee4abe09cb6ac.manifest

File version

Not applicable

File size

33,222

Date (UTC)

29-Feb-2012

Time (UTC)

06:53

File name

Wow64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7601.21932_none_4fc38efe14fd78a7.manifest

File version

Not applicable

File size

22,967

Date (UTC)

29-Feb-2012

Time (UTC)

05:42

Additional files for all supported IA-64–based versions of Windows Server 2008 R2

File name

Ia64_c1485606e2dd70df28d515fb3cb3595c_31bf3856ad364e35_6.1.7601.21932_none_d0574942d23c7572.manifest

File version

Not applicable

File size

1,058

Date (UTC)

29-Feb-2012

Time (UTC)

21:06

File name

Ia64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7601.21932_none_e951ed1e283d4e72.manifest

File version

Not applicable

File size

33,220

Date (UTC)

29-Feb-2012

Time (UTC)

06:48

File name

Wow64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7601.21932_none_4fc38efe14fd78a7.manifest

File version

Not applicable

File size

22,967

Date (UTC)

29-Feb-2012

Time (UTC)

05:42

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