RC4 pre-authentication failure for the Network Service account in Windows Server 2008 R2 or in Windows 7

Symptoms

Consider the following scenario:

  • A computer that is running Windows Server 2008 R2 or Windows 7 joins a domain.

  • The name of the domain contains at least one lowercase character.

  • You set the default authentication type for pre-authentication to RC4.

    Note When the following registry value is set to 0x17, RC4 is used as the default authentication type for pre-authentication:

    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa\Kerberos\Parameters\DefaultEncryptionType

  • You use the Network Service account to run a service.

In this scenario, authentication failure occurs, and the service might encounter various errors. Additionally, the following event is logged in the event log:

Event Type: Error

Event Source: Kerberos

Event Category: None

Event ID: 4

Date: <date>

Time: <time>

User:  N/A

Computer: <computer name>

Description:

The kerberos client received a KRB_AP_ERR_MODIFIED error from the server <name>. The target name used was <name>. This indicates that the password used to encrypt the kerberos service ticket is different than that on the target server. Commonly, this is due to identically named machine accounts in the target realm (<name>), and the client realm. Please contact your system administrator.

Cause

This issue occurs because the Kerberos authentication module generates an incorrect key for the Network Service account. Therefore, the service encounters authentication failure when it uses the account.

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 Web site:

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

  • Windows 7 Service Pack 1 (SP1)

  • Windows Server 2008 R2

  • 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 use 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, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:

    Version

    Product

    Milestone

    Service branch

    6.1.760
    0.21xxx

    Windows 7 and Windows Server 2008 R2

    RTM

    LDR

    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 7 and for Windows Server 2008 R2" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are critical to maintaining the state of the updated component. 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

Platform

Kerberos.dll

6.1.7600.21000

541,184

02-Jul-2011

04:25

x86

Kerberos.dll

6.1.7601.21762

542,208

02-Jul-2011

05:43

x86

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

6.1.7600.21000

714,752

02-Jul-2011

05:20

x64

Kerberos.dll

6.1.7601.21762

716,288

02-Jul-2011

05:14

x64

Kerberos.dll

6.1.7600.21000

541,184

02-Jul-2011

04:25

x86

Kerberos.dll

6.1.7601.21762

542,208

02-Jul-2011

05:43

x86

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

File name

File version

File size

Date

Time

Platform

Kerberos.dll

6.1.7600.21000

1,499,136

02-Jul-2011

04:11

IA-64

Kerberos.dll

6.1.7601.21762

1,500,160

02-Jul-2011

04:16

IA-64

Kerberos.dll

6.1.7600.21000

541,184

02-Jul-2011

04:25

x86

Kerberos.dll

6.1.7601.21762

542,208

02-Jul-2011

05:43

x86

Workaround

To work around this issue, delete the following registry entry on the problematic computer:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa\Kerberos\Parameters\DefaultEncryptionType

Status

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

More Information

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

837361 Kerberos protocol registry entries and KDC configuration keys in Windows Server 2003For 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

Update.mum

File version

Not applicable

File size

2,773

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

X86_4fe3c510df2be4e893a2a54c1de61da6_31bf3856ad364e35_6.1.7601.21762_none_25f9fce4fa09bd9b.manifest

File version

Not applicable

File size

705

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

X86_6a013f2000b3b5c94ab51e32ffeb78b5_31bf3856ad364e35_6.1.7600.21000_none_b2b50a8d5dc3b507.manifest

File version

Not applicable

File size

705

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

X86_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7600.21000_none_e7882fa82b028bfd.manifest

File version

Not applicable

File size

33,218

Date (UTC)

02-Jul-2011

Time (UTC)

04:53

Platform

Not applicable

File name

X86_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7601.21762_none_e92fd59828579efb.manifest

File version

Not applicable

File size

33,218

Date (UTC)

02-Jul-2011

Time (UTC)

06:44

Platform

Not applicable

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

File name

Amd64_0fb41cb5a45fee13fe1f7fb3ddd0941c_31bf3856ad364e35_6.1.7601.21762_none_894999101f815db4.manifest

File version

Not applicable

File size

1,060

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

Amd64_37f668002840c08572ee42c52d878500_31bf3856ad364e35_6.1.7601.21762_none_0c2c5181f4b73603.manifest

File version

Not applicable

File size

709

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

Amd64_aa78e01006f60ac136b52b5a81a31403_31bf3856ad364e35_6.1.7600.21000_none_0e85d7c398cac3f1.manifest

File version

Not applicable

File size

709

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

Amd64_f71ae8de4319b5483caf14ec6ea1b0b8_31bf3856ad364e35_6.1.7600.21000_none_00097e5260319ffa.manifest

File version

Not applicable

File size

1,060

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

Amd64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7600.21000_none_43a6cb2be35ffd33.manifest

File version

Not applicable

File size

33,222

Date (UTC)

02-Jul-2011

Time (UTC)

05:55

Platform

Not applicable

File name

Amd64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7601.21762_none_454e711be0b51031.manifest

File version

Not applicable

File size

33,222

Date (UTC)

02-Jul-2011

Time (UTC)

07:01

Platform

Not applicable

File name

Update.mum

File version

Not applicable

File size

3,215

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

Wow64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7600.21000_none_4dfb757e17c0bf2e.manifest

File version

Not applicable

File size

22,967

Date (UTC)

02-Jul-2011

Time (UTC)

04:44

Platform

Not applicable

File name

Wow64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7601.21762_none_4fa31b6e1515d22c.manifest

File version

Not applicable

File size

22,967

Date (UTC)

02-Jul-2011

Time (UTC)

06:33

Platform

Not applicable

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

File name

Ia64_2fbd51ccae1375f974fcc4691fed2b9f_31bf3856ad364e35_6.1.7600.21000_none_1b7055fe8e1a5820.manifest

File version

Not applicable

File size

1,058

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

Ia64_fee6985dac59f9888818be64acb428a5_31bf3856ad364e35_6.1.7601.21762_none_d1d82a7869b03c35.manifest

File version

Not applicable

File size

1,058

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

Ia64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7600.21000_none_e789d39e2b0094f9.manifest

File version

Not applicable

File size

33,220

Date (UTC)

02-Jul-2011

Time (UTC)

05:49

Platform

Not applicable

File name

Ia64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7601.21762_none_e931798e2855a7f7.manifest

File version

Not applicable

File size

33,220

Date (UTC)

02-Jul-2011

Time (UTC)

06:50

Platform

Not applicable

File name

Update.mum

File version

Not applicable

File size

2,168

Date (UTC)

02-Jul-2011

Time (UTC)

09:56

Platform

Not applicable

File name

Wow64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7600.21000_none_4dfb757e17c0bf2e.manifest

File version

Not applicable

File size

22,967

Date (UTC)

02-Jul-2011

Time (UTC)

04:44

Platform

Not applicable

File name

Wow64_microsoft-windows-security-kerberos_31bf3856ad364e35_6.1.7601.21762_none_4fa31b6e1515d22c.manifest

File version

Not applicable

File size

22,967

Date (UTC)

02-Jul-2011

Time (UTC)

06:33

Platform

Not applicable

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