Enterprise Active Directory Penetration Assessment
A comprehensive evaluation identifying lateral movement vectors, Kerberos ticket abuse, and domain privilege escalation across a multi-tiered corporate forest.
1. Technical Challenge
The client operated an enterprise Active Directory architecture comprising over 2,400 endpoints, multiple legacy domain controllers, and hybrid Azure AD synchronizations. While traditional endpoint antivirus software was active, the organization lacked visibility into internal credential delegation flaws and lateral movement abuse paths.
The primary engineering challenge was to execute an unannounced offensive simulation without causing service disruption across critical ERP databases, while probing whether an adversary with initial low-privileged access could chain configuration flaws to achieve Domain Admin dominance.
2. Engagement Scope & Parameters
The assessment was authorized under strict rules of engagement adhering to ISO 27001 and OWASP risk assessment frameworks:
Engagement Boundaries & Rules
- Phase 1 (External Perimeter): Passive and active reconnaissance against 64 public IPv4 hosts, DNS zone transfers, and external SSO endpoints.
- Phase 2 (Internal Network Simulation): Grey-box internal access simulated from a compromised workstation VLAN with standard unprivileged user credentials.
- Exclusions: Production database modification, destructive denial-of-service (DoS), and social engineering against non-security personnel were explicitly prohibited.
- Communication Channel: Direct encrypted operational bridge with the client's Chief Information Security Officer (CISO).
3. Vulnerability Reproduction & Attack Path
The escalation vector unfolded across four distinct technical stages:
Stage 1: Internal Broadcast Poisoning (LLMNR / NBT-NS)
Due to unconstrained legacy broadcast protocols on the local subnet, the assessment team utilized network listening to capture NetNTLMv2 authentication hashes when workstations attempted to resolve non-existent file shares.
Stage 2: Kerberoasting Legacy Service Principal Names (SPNs)
Using standard domain user authentication, the team queried Active Directory for user accounts associated with registered Service Principal Names (SPNs). Two legacy SQL service accounts were running with weak RC4-HMAC encryption.
Stage 3: Graphing Hidden ACL Permissions via BloodHound
BloodHound analysis revealed that the compromised svc_sqladmin account was a member of a delegated group granted GenericAll rights over an intermediate Tier-1 IT Administration security group.
By modifying group membership, the account inherited administrative access over the primary Domain Controller server backup share, facilitating complete domain dominance.
4. Business Impact & Risk Analysis
If exploited by a malicious actor, these chained weaknesses would have resulted in:
Executive Risk Scorecard
- Unrestricted Ransomware Deployment: An adversary obtaining Domain Admin could distribute malware to all 2,400+ endpoints via Group Policy Objects (GPO).
- Complete Data Exfiltration: Access to unencrypted customer databases, payroll archives, and proprietary ERP logistics.
- Regulatory Penalties: Failure of data fiduciary responsibilities leading to severe regulatory scrutiny and contractual breaches.
5. Remediation & Hardening Roadmap
The engineering team delivered a comprehensive remediation plan that was implemented within 15 days:
Implemented Engineering Fixes
- Protocol Lockdown: Disabled LLMNR and NBT-NS globally across all subnets via Active Directory Group Policy.
- Group Managed Service Accounts (gMSA): Migrated all SQL and backup service accounts to gMSAs with 128-bit automatic rotating passwords, completely eliminating Kerberoasting risk.
- Tiered Administration: Implemented strict Tier 0 / Tier 1 / Tier 2 separation. Domain Admin credentials are mathematically prohibited from logging onto lower-tier workstations.
- SIEM Detection Rules: Deployed real-time alerting for anomalous Kerberos TGS ticket requests exceeding normal user baselines.
A formal re-test conducted 15 days later verified that all privilege escalation paths were completely neutralized.
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