BloodHoundAD/BARK

BloodHound Attack Research Kit

BARK

BARK stands for BloodHound Attack Research Kit. It is a PowerShell script built to assist the BloodHound Enterprise team with researching and continuously validating abuse primitives. BARK currently focuses on Microsoft's Azure suite of products and services.

BARK requires no third party dependencies. BARK's functions are designed to be as simple and maintainable as possible. Most functions are very simple wrappers for making requests to various REST API endpoints. BARK's basic functions do not even require each other - you can pull almost any BARK function out of BARK and it will work perfectly as a standalone function in your own scripts.

Author and Contributors

Primary author: Andy Robbins @_wald0

Contributors:

• Jonas Bülow Knudsen @Jonas_B_K
• Fabian Bader @fabian_bader
• CravateRouge @CravateRouge
• g60ocR @g60ocR

Getting Started

There are many ways to import a PowerShell script. Here's one way:

First, download BARK.ps1 by cloning this repo or simply copy/pasting its raw contents from GitHub.

git clone https://github.com/BloodHoundAD/BARK

Now, cd into the directory where the PS1 is:

cd BARK

Finally, you can dot import the PS1 like this:

. .\BARK.ps1

Hit enter, and your PowerShell instance will now have access to all of BARK's functions.

Running your first BARK commands

With very few exceptions, Azure API endpoints require authentication to interact with. BARK comes with a few functions that will help you acquire the necessary tokens for interacting with the MS Graph and Azure REST APIs. Any BARK function that interacts with an Azure API that requires authentication will require you to supply a token.

Let's say you want to list all of the users in an Entra ID tenant. You first need to get a token scoped for MS Graph. There are many ways to get this token:

If you have a username/password combination for an Entra user in that tenant, you can first acquire a refresh token for the user using BARK's Get-EntraRefreshTokenWithUsernamePassword function:

$MyRefreshTokenRequest = Get-EntraRefreshTokenWithUsernamePassword -username "arobbins@contoso.onmicrosoft.com" -password "MyVeryCoolPassword" -TenantID "contoso.onmicrosoft.com"

The resulting object you just created, $MyRefreshTokenRequest, will have as part of it a refresh token for your user. You can now request an MS Graph-scoped token using this refresh token:

$MyMSGraphToken = Get-MSGraphTokenWithRefreshToken -RefreshToken $MyRefreshTokenRequest.refresh_token -TenantID "contoso.onmicrosoft.com"

Now this new object, $MyMSGraphToken, will have as one of its property values an MS Graph-scoped JWT for your user. You are now ready to use this token to list all the users in the Entra tenant:

$MyUsers = Get-AllEntraUsers -Token $MyMSGraphToken.access_token -ShowProgress

Once finished, the $MyEntraUsers variable will be populated by objects representing all of the users in your Entra tenant.

Token Management and Manipulation Functions

• Get-AzureKeyVaultTokenWithClientCredentials requests a token from STS with Azure Vault specified as the resource/intended audience using a client ID and secret.
• Get-AzureKeyVaultTokenWithUsernamePassword requests a token from STS with Azure Vault specified as the resource/intended audience using a user-supplied username and password.
• Get-AzurePortalTokenWithRefreshToken requests an Azure Portal Auth Refresh token with a user-supplied refresh token.
• Get-AzureRMTokenWithClientCredentials requests an AzureRM-scoped JWT with a client ID and secret. Useful for authenticating as an Entra service principal.
• Get-AzureRMTokenWithPortalAuthRefreshToken requests an AzureRM-scoped JWT with a user-supplied Azure Portal Auth Refresh token.
• Get-AzureRMTokenWithRefreshToken requests an AzureRM-scoped JWT with a user-supplied refresh token.
• Get-AzureRMTokenWithUsernamePassword requests an AzureRM-scoped JWT with a user-supplied username and password.
• Get-EntraRefreshTokenWithUsernamePassword requests a collection of tokens, including a refresh token, from login.microsoftonline.com with a user-supplied username and password. This will fail if the user has Multi-Factor Authentication requirements or is affected by a Conditional Access Policy.
• Get-MSGraphTokenWithClientCredentials requests an MS Graph-scoped JWT with a client ID and secret. Useful for authenticating as an Entra service principal.
• Get-MSGraphTokenWithPortalAuthRefreshToken requests an MS Graph-scoped JWT with a user-supplied Azure Portal Auth Refresh token.
• Get-MSGraphTokenWithRefreshToken requests an MS Graph-scoped JWT with a user-supplied refresh token.
• Get-MSGraphTokenWithUsernamePassword requests an MS Graph-scoped JWT with a user-supplied username and password.
• Parse-JWTToken will take a Base64 encoded JWT as input and parse it for you. Useful for verifying correct token audience and claims.

The refresh token-based functions in BARK are based on functions in TokenTactics by Steve Borosh.

Entra Enumeration Functions

• Get-AllEntraApps collects all Entra application registration objects.
• Get-AllEntraGroups collects all Entra groups.
• Get-AllEntraRoles collects all Entra admin roles.
• Get-AllEntraServicePrincipals collects all Entra service principal objects.
• Get-AllEntraUsers collects all Entra users.
• Get-EntraAppOwner collects owners of an Entra app registration.
• Get-EntraDeviceRegisteredUsers collects users of an Entra device.
• Get-EntraGroupMembers collects members of an Entra group.
• Get-EntraGroupOwner collects owners of an Entra group.
• Get-EntraRoleTemplates collects Entra admin role templates.
• Get-EntraServicePrincipal collects an Entra service principal.
• Get-EntraServicePrincipalOwner collects owners of an Entra service principal.
• Get-EntraTierZeroServicePrincipals collects Entra service principals that have a Tier Zero Entra Admin Role or Tier Zero MS Graph App Role assignment.
• Get-MGAppRoles collects the app roles made available by the MS Graph service principal.

Azure Resource Manager Enumeration Functions

• Get-AllAzureManagedIdentityAssignments collects all managed identity assignments.
• Get-AllAzureRMAKSClusters collects all kubernetes service clusters under a subscription.
• Get-AllAzureRMAutomationAccounts collects all automation accounts under a subscription.
• Get-AllAzureRMAzureContainerRegistries collects all container registies under a subscription.
• Get-AllAzureRMFunctionApps collects all function apps under a subscription.
• Get-AllAzureRMKeyVaults collects all key vaults under a subscription.
• Get-AllAzureRMLogicApps collects all logic apps under a subscription.
• Get-AllAzureRMResourceGroups collects all resouce groups under a subscription.
• Get-AllAzureRMSubscriptions collects all AzureRM subscriptions.
• Get-AllAzureRMVMScaleSetsVMs collects all virtual machines under a VM scale set.
• Get-AllAzureRMVMScaleSets collects all virtual machine scale sets under a subscription.
• Get-AllAzureRMVirtualMachines collects all virtual machines under a subscription.
• Get-AllAzureRMWebApps collects all web apps under a subscription.
• Get-AzureAutomationAccountRunBookOutput runs an automation account runbook and retrieves its output.
• Get-AzureFunctionAppFunctionFile collects the raw file (usually source code) of a function app function.
• Get-AzureFunctionAppFunctions collects all functions under a function app.
• Get-AzureFunctionAppMasterKeys collects all master keys under a function app.
• Get-AzureFunctionOutput runs a function app function and retrieves its output.
• Get-AzureRMKeyVaultSecretValue collects a key vault secret value.
• Get-AzureRMKeyVaultSecretVersions collects all versions of a key vault secret.
• Get-AzureRMKeyVaultSecrets collects all secrets under a key vault.
• Get-AzureRMRoleAssignments collects all role assignments against an object.
• Get-AzureRMRoleDefinitions collects all role definitions described at a subscription scope, including custom roles.
• Get-AzureRMWebApp collects a web app.

Intune Enumeration Functions

• Get-IntuneManagedDevices collects Intune-managed devices.
• Get-IntuneRoleDefinitions collects available Intune role definitions.

Entra Abuse Functions

• Add-MemberToEntraGroup will attempt to add a principal to an Entra group.
• Enable-EntraRole will attempt to enables (or "activate") the Entra role.
• New-EntraAppOwner will attempt to add a new owner to an Entra app.
• New-EntraAppRoleAssignment will attempt to grant an app role to a service principal. For example, you can use this to grant a service principal the RoleManagement.ReadWrite.Directory app role.
• New-EntraAppSecret will attempt to create a new secret for an existing Entra app registration.
• New-EntraGroupOwner will attempt to add a new owner to an Entra group.
• New-EntraRoleAssignment will attempt to assign an Entra admin role to a specified principal.
• New-EntraServicePrincipalOwner will attempt to will attempt to add a new owner to an Entra service principal.
• New-EntraServicePrincipalSecret will attempt to create a new secret for an existing Entra service principal.
• Reset-EntraUserPassword will attempt to reset the password of another user. If successful, the output will contain the new, Azure-generated password of the user.
• Set-EntraUserPassword will attempt to set the password of another user to a new user-provided value.

Azure Resource Manager Abuse Functions

• Invoke-AzureRMAKSRunCommand will instruct the AKS cluster to execute a command.
• Invoke-AzureRMVMRunCommand will attempt to execute a command on a VM.
• Invoke-AzureRMWebAppShellCommand will attempt to execute a command on a web app container.
• Invoke-AzureVMScaleSetVMRunCommand will attempt to execute a command on a VM Scale Set VM.
• New-AzureAutomationAccountRunBook will attempt to add a runbook to an automation account.
• New-AzureKeyVaultAccessPolicy will attempt to grant a principal "Get" and "List" permissions on a key vault's secrets, keys, and certificates.
• New-AzureRMRoleAssignment will attempt to grant a user-specified AzureRM role assignment to a particular principal over a certain scope.
• New-PowerShellFunctionAppFunction will attempt to create a new PowerShell function in a function app.

Meta Functions

• ConvertTo-Markdown is used for massaging output from the Invoke-Tests functions for usage in another platform.
• Invoke-AllAzureMGAbuseTests performs all abuse validation tests that can be executed by holding an MS Graph app role. Returns an object describing which privileges were successful at performing each abuse test.
• Invoke-AllAzureRMAbuseTests performs all AzureRM abuse validation tests and outputs a resulting object that describes which AzureRM roles granted the ability to perform each abuse.
• Invoke-AllEntraAbuseTests performs all abuse validation tests that can be executed by principals granted Entra admin roles. Returns an object describing which privileges were successful at performing each abuse test.
• New-EntraIDAbuseTestSPs creates a new service principal per active Entra admin role and grants each service principal the appropriate role. Returns plain text credentials created for each service prinicpal.
• New-EntraIDAbuseTestUsers creates a new user per active Entra admin role and grants each user the appropriate role. Returns plain text credentials created for each user.
• New-IntuneAbuseTestUsers creates a new user per Intune role and grants each user the appropriate role. Returns plain text credentials created for each user.
• New-MSGraphAppRoleTestSPs creates a new service principal per MS Graph app role and grants each service principal the appropriate role. Returns plain text credentials created for each service prinicpal.
• New-TestAppReg creates an application registration object for the explicit purpose of abuse validation testing.
• New-TestSP creates a new service principal and associates it with the app created by the above function.
• Remove-AbuseTestAzureRMRoles is a clean-up function for removing AzureRM admin roles created during testing.
• Remove-AbuseTestServicePrincipals cleans up abuse tests by removing the serivce principals that were created during testing.
• Test-AzureRMAddSelfToAzureRMRole used in abuse validation testing to determine whether a service principal with certain rights can grant itself the User Access Admin role over a subscription.
• Test-AzureRMCreateFunction used in abuse validation testing to test if a service principal can add a new function to an existing function app.
• Test-AzureRMPublishAutomationAccountRunBook is used to test whether a service principal can publish a new runbook to an existing automation account.
• Test-AzureRMVMRunCommand is used to test whether a principal can run a command on an existing VM.
• Test-MGAddMemberToNonRoleEligibleGroup is used to test whether the service principal can add itself to a non-role eligible group.
• Test-MGAddMemberToRoleEligibleGroup is used to test whether the service principal can add itself to a role eligible group.
• Test-MGAddOwnerToNonRoleEligibleGroup is used to test whether a service principal can grant itself explicit ownership of a non-role eligible group.
• Test-MGAddOwnerToRoleEligibleGroup is used to test whether a service principal can grant itself explicit ownership of a role eligiblee group.
• Test-MGAddRootCACert is used to test whether a service principal can add a new Root CA cert to the tenant.
• Test-MGAddSecretToApp is used to test whether the service principal can add a new secret to an existing app.
• Test-MGAddSecretToSP is used to test whether the service principal can add a new secret to an existing service principal.
• Test-MGAddSelfAsOwnerOfApp is used in abuse validation testing to determine whether a service principal with a particular privilege can grant itself ownership of an existing Entra app.
• Test-MGAddSelfAsOwnerOfSP is used in abuse validation testing to determine whether a service principal with a particular privilege can grant itself ownership of an existing Entra service principal.
• Test-MGAddSelfToEntraRole is used in abuse validation testing to determine whether a service principal with a particular privilege can add itself to an Entra admin role - Global Admin, for example.
• Test-MGAddSelfToMGAppRoleis used in abuse validation testing to determine whether a service principal with a particular privilege can grant itself a particular MS Graph app role without admin consent.