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Introduction
In a recent incident, attackers escalated from a compromised Ivanti appliance to Domain Admin privileges in under eight minutes by exploiting misconfigured Active Directory Certificate Services (ADCS) and default machine account settings. This highlights critical security gaps in certificate templates and authentication controls that organizations must address.
Learning Objectives
- Understand how attackers abuse vulnerable certificate templates for privilege escalation.
- Learn to mitigate MachineAccountQuota risks in Active Directory.
- Identify hardening techniques for ADCS and enterprise PKI.
You Should Know
1. Exploiting Vulnerable Certificate Templates
Command: Check vulnerable templates using PowerShell:
Get-CertificateTemplate -Name "" | Where-Object { $_.SchemaVersion -lt 2 } | Select-Object Name, SchemaVersion
Step-by-Step:
- Run the command to list certificate templates with outdated schema versions (v1 templates lack security descriptors).
- Identify templates permitting SAN-based enrollment for arbitrary users.
- Disable or update these templates to enforce stricter issuance policies.
2. Bypassing Enrollment Restrictions via MachineAccountQuota
Command: Audit default computer account creation permissions:
Get-ADObject -Identity "CN=Directory Service,CN=Windows NT,CN=Services,CN=Configuration,DC=domain,DC=com" -Properties ms-DS-MachineAccountQuota
Step-by-Step:
- The default `ms-DS-MachineAccountQuota=10` allows authenticated users to create computer objects.
- Attackers abuse this to enroll certificates from restricted templates.
- Mitigate by setting the quota to `0` or restricting computer account creation to privileged groups.
3. Detecting Malicious Certificate Enrollment
Command: Monitor certificate requests in Windows Event Logs:
Get-WinEvent -LogName "Microsoft-Windows-CertificateServicesClient-Lifecycle-System/Operational" | Where-Object { $_.Id -eq 4886 }
Step-by-Step:
1. Filter for Event ID 4886 (“Certificate enrolled”).
- Investigate abnormal requests (e.g., SAN spoofing, atypical requestor IPs).
- Enable CA auditing via
certutil -setreg CA\AuditFilter 127.
4. Hardening ADCS with EPA (Enrollment Policy Agent)
Command: Enforce EPA for template issuance:
certutil -setreg Policy\EditFlags +EDITF_ATTRIBUTEENDDATE
Step-by-Step:
1. Restrict templates to require EPA approval.
- Configure Issuance Requirements in the CA console to mandate manual approval for sensitive templates.
5. Blocking NTLM Relay to ADCS
Command: Disable NTLM on CA servers:
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa" -Name "LmCompatibilityLevel" -Value 5
Step-by-Step:
- Set NTLM compatibility level to 5 (“NTLMv2 only”).
2. Disable HTTP-based enrollment (`certutil -setreg CA\InterfaceFlags +IF_NONETWORKAUTHREQUESTS`).
What Undercode Say
- Key Takeaway 1: ADCS misconfigurations are a goldmine for attackers. Regularly audit templates and enforce schema version upgrades.
- Key Takeaway 2: Default AD settings like MachineAccountQuota must be hardened—assume breach and limit lateral movement.
Analysis: The eight-minute compromise window underscores how attackers chain low-risk misconfigurations into catastrophic breaches. Proactive measures like certificate template least-privilege, EPA enforcement, and NTLM hardening could have prevented this. Organizations must shift from reactive to continuous threat modeling, especially for PKI, which often operates with excessive trust.
Prediction
As attackers refine ADCS exploitation tools (e.g., Certify, ForgeCert), we’ll see a surge in certificate-based lateral movement. Future defenses will likely integrate AI-driven anomaly detection for real-time enrollment monitoring, but foundational hardening remains critical.
IT/Security Reporter URL:
Reported By: Stephan Berger – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
