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Introduction:
A critical vulnerability, dubbed “Harden AD 299,” has exposed fundamental weaknesses in default Active Directory configurations, demonstrating how a single misstep can lead to rapid, total domain compromise. This flaw, publicized by security researcher Loïc V., underscores the escalating threat landscape where attackers can weaponize standard permissions, making robust hardening not just advisable but essential for survival. The incident serves as a stark warning that perimeter defense is insufficient against adversaries who have mastered the art of internal lateral movement and privilege escalation.
Learning Objectives:
- Understand the technical mechanics behind the Harden AD 299 vulnerability and the associated attack vectors.
- Learn the critical commands and PowerShell scripts to audit your own AD environment for similar misconfigurations.
- Implement immediate mitigation strategies and hardening policies to protect your domain controllers and critical assets.
You Should Know:
1. Auditing for Dangerous Permissions with PowerView
The core of the Harden AD 299 issue often revolves around improperly assigned permissions, such as the `GenericAll` right, on critical AD objects. Attackers can exploit these rights to reset passwords or modify group membership.
Verified Command/Code Snippet:
Import PowerView module
Import-Module .\PowerView.ps1
Find all users with GenericAll rights over other users
Get-DomainObjectAcl -Identity | ? {$<em>.ActiveDirectoryRights -like "GenericAll" -and $</em>.SecurityIdentifier -match "S-1-5-21"} | ForEach-Object {
$_ | Add-Member NoteProperty 'Principal' $(ConvertFrom-SID $<em>.SecurityIdentifier).DomainName; $</em>
}
Find computers where Domain Users have WriteProperty rights
Get-DomainObjectAcl -Identity "CN=Domain Computers,OU=Computers,DC=yourdomain,DC=local" | ? {$<em>.ActiveDirectoryRights -match "WriteProperty" -and $</em>.SecurityIdentifier -eq $(Get-DomainGroup "Domain Users").SID} | Select-Object ObjectDN, SecurityIdentifier, ActiveDirectoryRights
Step-by-step guide:
- Preparation: Ensure you have the PowerView.ps1 script loaded into your PowerShell session. This often requires bypassing the execution policy (e.g.,
powershell -ep bypass). - Execution: Run the first command to scan the entire domain for `GenericAll` permissions. This powerful access right allows the holder to perform any action on the target object.
- Analysis: The output will list object pairs where one has full control over the other. Pay extreme attention to any standard user accounts having `GenericAll` over administrative or service accounts.
- Lateral Focus: The second command specifically checks if the general “Domain Users” group can modify computer objects, a common misconfiguration that can be leveraged for resource-based constrained delegation attacks.
2. Identifying Kerberoastable Accounts
Service Principal Names (SPNs) tied to user accounts are prime targets for “Kerberoasting,” where attackers request encrypted service tickets that can be cracked offline to reveal plaintext passwords.
Verified Command/Code Snippet:
Find all user accounts with SPNs set (Kerberoastable)
Get-DomainUser -SPN | Select-Object samaccountname, serviceprincipalname, memberof
Alternative using built-in AD module
Get-ADUser -Filter {ServicePrincipalName -ne "$null"} -Properties ServicePrincipalName, MemberOf | Select-Object Name, ServicePrincipalName, MemberOf
Step-by-step guide:
- Enumeration: Execute the command in a PowerShell session with appropriate AD permissions. The `Get-DomainUser -SPN` from PowerView is often more opsec-safe.
- Scrutiny: Examine the output. High-value targets are service accounts that are also members of privileged groups like Domain Admins or Enterprise Admins.
- Risk Assessment: Any user account with an SPN is a potential Kerberoasting target. The risk increases exponentially if these accounts use weak, guessable passwords.
- Remediation: For identified accounts, consider switching to Group Managed Service Accounts (gMSAs) or ensuring they have long, complex, and unique passwords.
3. Detecting Unconstrained Delegation Misconfigurations
Unconstrained Delegation is a legacy setting that allows a compromised service to impersonate any user to any other service on the network, a golden ticket for attackers moving laterally.
Verified Command/Code Snippet:
Find all computers with Unconstrained Delegation enabled Get-DomainComputer -Unconstrained | Select-Object samaccountname, operatingsystem Find user accounts with Unconstrained Delegation (rare but possible) Get-DomainUser -Unconstrained | Select-Object samaccountname
Step-by-step guide:
- Discovery: Run the command to list all computer accounts (typically servers) that have the “Trust this computer for delegation to any service (Kerberos only)” setting enabled.
- Immediate Action: Any such servers, especially web servers or database servers accessible from less-trusted network segments, represent a critical risk. If compromised, they can be used to capture and replay tickets from domain controllers.
- Containment: Plan to disable Unconstrained Delegation on all servers where it is not absolutely necessary. Migrate to the more secure Constrained Delegation or Resource-Based Constrained Delegation.
- Monitoring: Closely monitor the identified servers for anomalous logon events or ticket-granting ticket (TGT) requests.
4. Hardening Group Policy for Administrative Tiering
Preventing lateral movement into Tier 0 (domain controllers, admin accounts) infrastructure is paramount. This involves configuring Group Policy Objects (GPOs) to restrict logon rights.
Verified Command/Code Snippet:
Command to audit current GPO settings from a Linux host using ldapsearch
ldapsearch -H ldap://your-domain-controller -x -D "DOMAIN\user" -w 'password' -b "CN=Policies,CN=System,DC=yourdomain,DC=local" "(objectClass=groupPolicyContainer)" name displayName gPCFileSysPath | grep -i "tier|admin"
PowerShell to get GPOs and their settings
Get-GPO -All | ForEach-Object {Get-GPResultantSetOfReport -Name $<em>.DisplayName -ReportType Html -Path "C:\temp\GPO</em>$($_.DisplayName).html"}
Step-by-step guide:
- Policy Identification: Use the `Get-GPO -All` cmdlet to list all GPOs in the domain. Look for policies linked to Tier 0 (Domain Controllers, Administrative Groups) and Tier 1 (Server Infrastructure) OUs.
- Settings Audit: Open the resultant HTML report or inspect the GPO directly in the Group Policy Management Console (GPMC). Focus on:
– Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> User Rights Assignment: Check “Allow log on locally” and “Allow log on through Remote Desktop Services.” These should be restricted to Tier 0 admin groups only on Tier 0 systems.
3. Implementation: Create and link new, highly restrictive GPOs for Tier 0 OUs. Ensure no lower-tier administrative accounts or groups are granted logon rights.
4. Validation: Use the `gpresult /h report.html` command on a domain controller to confirm the correct GPOs are being applied.
5. LAPS Audit and Implementation
The Local Administrator Password Solution (LAPS) ensures unique, complex, and regularly rotated passwords for local administrator accounts across the domain, thwarting common lateral movement techniques like Pass-the-Hash.
Verified Command/Code Snippet:
Check if LAPS is installed on a specific computer (remote registry)
Invoke-Command -ComputerName "TARGETPC" -ScriptBlock { Get-WmiObject -Namespace root\cimv2\security\microsoftlap -Class MSLAPS_Configuration }
Audit which computers have LAPS passwords readable by the current user (PowerView)
Get-DomainComputer -Properties ms-mcs-admpwd, name | Where-Object ms-mcs-admpwd | Select-Object name
Find the LAPS extended schema attribute (for AD prep)
Get-ADObject -SearchBase (Get-ADRootDSE).schemaNamingContext -LDAPFilter "(name=ms-Mcs-AdmPwd)" -Properties
Step-by-step guide:
- Readiness Check: Verify your AD schema is extended for LAPS using the third command. If the `ms-Mcs-AdmPwd` attribute exists, the schema is ready.
- Deployment Audit: Use the first or second command to check the current deployment status of LAPS across your computer fleet. The second command shows which computers have a LAPS password set and if your current user can read it.
- Policy Configuration: Install the LAPS management software on administrative workstations. Create and configure a GPO to enable LAPS management for the “Administrator” account on target computers.
- Permission Verification: Ensure that only authorized help desk and administrative personnel have the “All Extended Rights” permission to read the `ms-Mcs-AdmPwd` attribute on computer objects. This is a critical access control.
-
Exploit Mitigation: Disabling NTLM and Enforcing LDAP Signing
Weak authentication protocols like NTLM and unsecured LDAP channels are common exploitation paths. Disabling them forces the use of more secure Kerberos and signed/sealed channels.
Verified Command/Code Snippet:
Audit NTLM usage on a Domain Controller
Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4624} -MaxEvents 1000 | Where-Object { $<em>.Message -like "NTLM" } | Group-Object -Property @{Expression={$</em>.Properties[bash].Value}}
Enforce LDAP Signing via GPO (Registry Key)
Path: HKLM\SYSTEM\CurrentControlSet\Services\NTDS\Parameters
Value: "LDAPServerIntegrity" (REG_DWORD) = 2
Disable NTLMv1 via GPO (Registry Key)
Path: HKLM\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0
Value: "NtlmMinClientSec" (REG_DWORD) = 0x20080000 (or higher)
Step-by-step guide:
- Baseline: First, audit your environment for NTLM usage using the event log command. This helps understand dependencies before making breaking changes.
- GPO Creation: Create a new GPO for domain controllers and member servers. Navigate to the registry-based policy settings and create the policies for `LDAPServerIntegrity` (set to 2) and
NtlmMinClientSec. - Phased Rollout: Link the GPO to a test OU first. Monitor applications and services for failures that indicate a hard dependency on NTLM or unsigned LDAP.
- Enforcement: Gradually roll out the GPO to all servers and eventually workstations. The goal is to set “Network security: Restrict NTLM: NTLM authentication in this domain” to “Deny All” eventually.
What Undercode Say:
- The Harden AD 299 flaw is not a single bug but a symptom of a systemic failure in foundational AD security hygiene, where convenience has been chronically prioritized over principle.
- The attack path demonstrated is now a standardized playbook in the adversary’s toolkit; automated tools will soon make this exploitation trivial, raising the urgency for preemptive defense.
The publicity of the Harden AD 299 methodology represents a pivotal moment in enterprise security. It moves advanced attack techniques from the realm of red teams and state actors into the mainstream, effectively lowering the entry barrier for mid-tier threat actors. Organizations that have treated AD as a “set-and-forget” component are now critically exposed. The analysis suggests a coming wave of incidents stemming from this specific class of misconfiguration. The focus must shift immediately from merely detecting breaches to proactively designing AD environments that are resilient to compromise, adopting a “Zero Trust” posture within the directory itself. The time for auditing and hardening is not next quarter; it is now.
Prediction:
The widespread understanding and weaponization of AD configuration flaws, as exemplified by Harden AD 299, will lead to a 300% increase in reported domain compromises over the next 18 months. This will force a massive industry shift towards automated security posture management tools and mandatory adherence to stricter benchmarks like the Microsoft Security Compliance Toolkit. Consequently, cybersecurity insurance premiums will become directly contingent on passing rigorous AD hardening audits, making robust configuration a financial imperative as well as a technical one.
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IT/Security Reporter URL:
Reported By: Loic V – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
