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Using a Task Sequence Secret Value when changing a local password

At one time it became routine to manage Windows local account passwords with a Group Policy Preference.  However, some time ago the process was was discovered to have a significant venerability and Microsoft released security bulletin MS14-025 to address the issue.  But Microsoft didn’t fix the vulnerability.  Instead they removed the ability for GPP to save user names and passwords in Local Users and Groups, Drive Maps, Scheduled Tasks, Services, and Data Sources.

There are many options to handle managing local account passwords including:

  • MS14-025 includes a lengthy PowerShell script which will reach-out to remote computers to change the password and log the change in a central text file
  • Microsoft Local Administrator Password Solution (LAPS) is a great free solution which should be seriously considered
  • ConfigMgr (SCCM / Microsoft System Center Configuration Manager) deployment
  • a dozen other options not listed here

While discussing the ConfigMgr options with a few colleagues we came up with the following:

  • Application or Package deployment with a script which has an embedded password or uses a password formula / calculation
  • A Compliance Setting and Baseline with a script a script which has an embedded password or uses a password formula / calculation
  • A Task Sequence deployment with a script which has an embedded password

I’ve created a Compliance Setting and Baseline for a customer in a situation where they had ConfigMgr clients on workgroups and joined to domains which they could not manage.  This worked really well for them.  The embedded script used a simple Base64 conversion to obfuscate the password and the password was not exposed on the command line, but there was no actual encryption.

Turning to the Task Sequence discussion option, a suggestion was made to call NET USER from a Run Command action.  This sounded easy.  Too easy.  Besides, wouldn’t the command including the password be exposed in SMSTS.log?  Not if a “Secret Value” Task Sequence Variable is used!

Follow these steps in configuring a Task Sequence:

Set a Task Sequence Variable named ADMPW or similar, enter the clear text value, then enable the “Secret value” check box.

Select OK to save/close the variable properties, then look at it again and notice that the value is quite different than what you’ve typed.  It’s encrypted!

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Now, call the NET USER command line with the variable

NET USER administrator %ADMPW%

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Reviewing the SMSTS.log helps validate that the password is not exposed.

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The log only shows “Action command line: smsswd.exe /run: net user administrator %ADMPW%

 

The ConfigMgr Task Sequence using a “Secret Value” Variable can be an effective method of changing local account password.

5 Comments

  1. Algar August 4, 2016
    • Jake February 17, 2017
  2. Steve November 23, 2016
    • Steve December 5, 2016
  3. Jake February 17, 2017

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