Category: Active Directory


Introduction:

Querying the Windows Security Account Manager (SAM) remotely via the SAM-Remote (SAMR) protocol against their victim’s domain machines, allows the attackers to get all domain and local users with their group membership and map possible routes within the victim’s network. Recently, some frameworks (e.g. BloodHound) have automated that mapping process.

By default, the SAM can be accessed remotely (via SAMR) by any authenticated user, including network connected users, which effectively means that any domain user is able to access it. Windows 10 had introduced an option to control the remote access to the SAM, through a specific registry value. On Windows Anniversary update (Windows 10 Version 1607) the default permissions were changed to allow remote access only to administrators. An accompanying Group Policy setting was added, which gives a user-friendly interface to alter these default permissions.

SAMR: Remote Querying of SAM

The Security Account Manager Remote Protocol (SAMR) exposes the security accounts manager database for a remote authenticated domain user. It does so for both local and domain accounts. There are five objects that are exposed by the protocol; server, domain, group, alias and user. All these objects can be updated and read, and some (user, group and alias) can also be created and deleted.

Flow and Usage

The basic flow of using the SAMR protocol is as such:

  1. Connect to a server (the remote machine).
  2. Enumerate/lookup the server for domains.
  3. Open the domain of interest.
  4. Lookup a user or alias/group in the domain.
  5. Open the user/alias of interest.
  6. Query the user/alias of interest.

There are a few tools that utilize these API calls, such as Net User/Group, PowerSploit’s Get-NetLocalGroup and Imapcket’s SAMRdump. Net User and Net Group are Windows built-in command line tools. With these tools an authenticated user can add or modify and display information on users or groups respectively on the local machine or its domain controller. The Get-NetLocalGroup queries a remote machine for its local groups (including the “Administrators” and “Users” groups). SAMRdump, queries the target machine for its local users (using the EnumDomainUsers on the target machine). MicrosoftATA detects the use of such query and alerts the security administrator about it.

Hardening SAM Remote access: https://gallery.technet.microsoft.com/SAMRi10-Hardening-Remote-48d94b5b

 

 

 

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GPO – backup all

To backup all GPOs: Backup-Gpo -All -Path \\myserver\gpobackup

http://info.adaptivedge.com/blog/2017/04/30/how-to-enable-office-365-group-writeback-for-a-hybrid-coexistence-environment

A colleague of mine found this interesting article:

https://blogs.msdn.microsoft.com/chiranth/2013/09/20/ntlm-want-to-know-how-it-works/

 

GPO Basics:

1) Structure of a GPO:

Group Policy Container (GPC) which exists in Active Directory

and the Group Policy Template (GPT) where the actual content of your GPOs resides.

A third component, known as Client-Side Extensions (CSEs) can be found on client devices and are necessary for them to properly process the Group Policies assigned to them.

ref: http://blogs.technet.com/b/musings_of_a_technical_tam/archive/2012/02/13/understanding-the-structure-of-a-group-policy-object.aspx

2) GPO processing (LSDOU):

ref: http://blogs.technet.com/b/musings_of_a_technical_tam/archive/2012/02/15/understanding-the-structure-of-a-group-policy-object-part-2.aspx

3) GPO troubleshooting:

http://social.technet.microsoft.com/wiki/contents/articles/22457.10-common-problems-causing-group-policy-to-not-apply.aspx

https://technet.microsoft.com/en-us/magazine/ccba8171-2b4a-4437-ab45-bbdee8323ee2

 

GPO management with PowerShell:

Powershell – how to translate a GPO GUID to Name?

Get-GPO -GUID “{AD7E3746-7135-496B-A1F5-B5B11871F96F}”

Powershell – how list all GPOs?

Get-GPO -all

Get-GPo -all | ft -autosize

Get-GPO -all | out-gridview

Powershell – how many GPOs?

(get-gpo -all).count
203

Powershell – how to translate a GPO Name to GUID?

PS Z:\ADGPO management> Get-GPO -all | where {$_.id -like “bd9df1be-3663-4cb4-bb71-35f7e27c691f”} | select id,displayname | ft -autosize

Id                                   DisplayName
—                                   ———–
bd9df1be-3663-4cb4-bb71-35f7e27c691f Corporate-A-All-Settings-Restore

 

Powershell – create and link a GPO?

 

PS C:\> Get-GPStarterGPO -Name “Laptops”
Next, you can use the New-GPO cmdlet to create the new GPO from your Starter GPO as follows:

PS C:\> New-GPO -Name “France-Laptops” -StarterGpoName “Laptop”

Finally, you can link the new GPO to the targeted OU as follows:

PS C:\> New-GPLink -Name “France-Laptops” -Target “ou=computers,ou=France,dc=hq,dc=mydomain,dc=com”

Alternatively, by using the Windows PowerShell pipeline feature, you can create and link the GPO using a single command.

With AAD Connect,

The following filtering configuration types can be applied to the Directory Synchronization tool:

  • Group based: Filtering based on a single group can only be configured on initial install using the installation wizard. It is not further covered in this topic.
  • Domain-based: This option enables you to select which domains will synchronize to Azure AD. It also allows you to add and remove domains from the sync engine configuration if you make changes to your on-premises infrastructure after you installed Azure AD Connect sync.
  • Organizational-Unit–based: This filtering option enables you to select which OUs will synchronize to Azure AD. This option will be on all object types in selected OUs.
  • Attribute–based: This option allows you to filter objects based on attribute values on the objects. You can also have different filters for different object types.

You can use multiple filtering options at the same time. For example you can use OU-based filtering to only include objects in one OU and at the same time attribute-based filtering to filter the objects further. When you use multiple filtering methods, the filters use a logical AND between the filters.

Filtering can be applied both on the inbound from Active Directory to the metaverse and outbound from the metaverse to Azure AD. It is recommended to apply filtering on inbound since that is the easiest to maintain. Outbound filtering should only be used if is required to join objects from more than one forest before the evaluation can take place.

Articles about AAD Connect filtering customization:

https://dirteam.com/dave/2015/04/06/azure-active-directory-synchronization-filtering-part-1/

https://help.bittitan.com/hc/en-us/articles/115008113387-How-do-I-filter-objects-using-Azure-Active-Directory-AAD-Connect-

https://github.com/MicrosoftDocs/azure-docs/blob/master/articles/active-directory/connect/active-directory-aadconnectsync-configure-filtering.md

 

 

 

 

Windows Admin Center:

https://docs.microsoft.com/en-us/windows-server/manage/windows-admin-center/overview

https://blogs.technet.microsoft.com/servermanagement/2018/04/12/windows-admin-center-formerly-project-honolulu-is-now-generally-available/

https://cloudblogs.microsoft.com/windowsserver/2018/04/12/announcing-windows-admin-center-our-reimagined-management-experience/

Installation:

You can install Windows Admin Center on the following Windows operating systems:

Version Installation Mode
Windows 10 (1709) Desktop mode
Windows Server, version 1709 Gateway mode
Windows Server 2016 Gateway mode

Desktop Mode: Connect to the Windows Admin Center gateway from the same computer on which it’s installed (for example, https://localhost:6516)

Gateway Mode: Connect to the Windows Admin Center gateway from a client browser on a different machine (for example, https://servername)

This was one of the main blockers of Firefox adoption in the enterprise : https://bugzilla.mozilla.org/show_bug.cgi?id=1433136

 

Reference: http://support.microsoft.com/kb/318785

Microsoft .net Framework is a software package that is used by many applications, it runs in a software environment as opposed to hardware environment.

Free program called .NET Version Detector ( download here ).

PowerShell: how to get version of .net framework on a remote computer: https://gallery.technet.microsoft.com/scriptcenter/Detect-NET-Framework-120ec923

To query the local Registry using PowerShell, execute the below command in an elevated PowerShell session.

(Get-ItemProperty ‘HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full’  -Name Release).Release

You can then use the table below to reference the installed version of .NET. For instance, if the returned value is 379893, then .NET 4.5.2 is installed.

Those laptops must run the latest Windows 10 OS with all the new security features and security best practices like:

  • Apply a Hardening Security Baseline from Microsoft Security Compliance Manager (SCM)
  • Enable Secure Boot with UEFI
  • Impose Software Restrictions using AppLocker
  • Enable Full Disk Encryption.
  • Impose Restrictions on USB ports.
  • Implement Network Isolation via host firewall
  • Install and configure the Device Guard, Windows defender ATP or equivalent + Crowdstrike or equivalent
  • Don’t allow Internet access from a browser.
  • Install Minimal Software.
  • Allow Minimal Administrative Accounts (gad-xxxx accounts in our case)
  • Implement a Hardened OU for the PAWs into the GAD of MUCMSPDOM