From a Standard Domain Account to Domain Administrator: An Active Directory Penetration Test Walkthrough

Description: Password-spraying activities identified widespread credential reuse across domain user accounts. A single spray attempt against the enumerated user list successfully authenticated against approximately 189 accounts using an identical password - including a highly privileged Domain Administrator account. This alone was sufficient to escalate from a standard, low-privileged starting account to full domain compromise, without exploiting any software vulnerability.

Risk/Impact: Unauthorized access to user and administrative accounts, lateral movement, privilege escalation, and compromise of critical enterprise systems and resources.

Recommendation: Enforce strong, unique passwords across all domain accounts with technical password-filtering controls prohibiting reuse; implement multi-factor authentication for privileged and critical accounts; conduct periodic password audits to identify weak or reused credentials; and deliver targeted user awareness training on secure password practices.

Description: Endpoint security controls deployed within the environment could be bypassed by establishing an unauthorized outbound tunnel from a domain-joined workstation to external infrastructure. Assessment traffic and tooling were routed through this tunnel without effective prevention or detection, indicating insufficient outbound restrictions and inadequate monitoring of tunneling activity.

Risk/Impact: Attackers could bypass endpoint monitoring, establish persistent covert command-and-control channels, exfiltrate sensitive data, and execute malicious tooling within the internal network without effective detection.

Recommendation: Restrict unauthorized outbound communications via firewall and proxy controls; implement detection for tunneling, proxying and anomalous encrypted egress; enforce application allowlisting to restrict unauthorized networking utilities; and strengthen EDR monitoring for suspicious process behaviour and tunneling activity.

Description: Sensitive credentials, authentication tokens, vault-related files, API keys, and cloud/SaaS/database secrets were stored within user-accessible shared locations across the environment, without adequate access restrictions - covering cloud platforms, internal services, SaaS applications and administrative resources.

Risk/Impact: Attackers with low-privileged access could obtain sensitive credentials and authentication material, resulting in unauthorized access to internal systems, cloud services, SaaS platforms, databases and other critical business resources.

Recommendation: Remove sensitive credentials and secrets from shared, user-accessible locations; implement a secure credential storage solution such as a password vault or secrets manager; restrict access based on least-privilege principles; rotate exposed credentials, API keys and tokens immediately; and conduct periodic audits to identify newly exposed secrets.

Description: Multiple network shares across the environment were configured with overly permissive access controls, with many fully open and requiring no credentials at all. Accessible content included business-critical files, administrative data, backups, mail archives, and internal documentation - a strong foothold for further compromise for any low-privileged or unauthenticated user.

Risk/Impact: Unauthorized access to sensitive organisational information, client-related data, internal operational resources and backup data, increasing the risk of data disclosure, lateral movement and broader domain compromise.

Recommendation: Review and restrict network share permissions based on the principle of least privilege; remove unnecessary access granted to low-privileged or authenticated users; periodically audit shared resources for sensitive information exposure; and implement data classification and access governance controls for critical organisational data.

Description: The domain password policy enforced insufficient complexity and length requirements: an 8-character minimum length, a password history of only 5, a 0-day minimum password age, and a 5-attempt lockout threshold - configuration that directly contributed to the successful compromise of multiple domain accounts during the assessment.

Risk/Impact: Significantly increased likelihood of successful password spraying, brute-force attacks, credential compromise and unauthorized access to enterprise systems.

Recommendation: Increase minimum password length to at least 14 characters for standard accounts and 20 characters for privileged accounts; implement a banned-password list; increase password history enforcement; and deploy multi-factor authentication for privileged and sensitive accounts.

Description: Link-Local Multicast Name Resolution (LLMNR) and NetBIOS Name Service (NBT-NS) were enabled within the environment and were successfully abused to capture NTLM authentication hashes from domain users. Captured hashes were subsequently cracked offline, resulting in unauthorized access to additional user accounts.

Risk/Impact: Credential interception, offline hash cracking, unauthorized access, lateral movement and potential privilege escalation.

Recommendation: Disable LLMNR and NBT-NS across the environment via Group Policy; enforce SMB signing where applicable; implement network segmentation to restrict unnecessary broadcast traffic; and monitor for suspicious name-resolution and credential-interception activity.

Description: Machine accounts within Active Directory had Service Principal Names (SPNs) registered that could be enumerated and requested by any authenticated domain user, with the retrieved Kerberos service tickets subject to offline cracking attempts. While machine account passwords are typically strong, auto-generated and regularly rotated, this exposure still expands the attack surface available to a low-privileged attacker.

Risk/Impact: Aids reconnaissance and enumeration capability; in combination with weak or legacy encryption configurations, may present opportunities for credential recovery, though success against machine accounts is unlikely under default configurations.

Recommendation: Ensure machine account passwords rotate on the default schedule; enforce Kerberos AES encryption and disable legacy RC4-HMAC encryption; monitor for abnormal volumes of TGS-REQ requests indicative of Kerberoasting; and review and remove unnecessary SPNs registered against machine accounts.

A grey-box AD penetration test starts the tester with a limited, defined level of access - typically a domain-joined workstation and a standard, low-privileged user account - rather than zero access (black-box) or full administrative visibility (white-box). This mirrors the realistic position of an attacker who has already obtained an initial foothold through phishing, a compromised endpoint, or a low-trust account, and focuses testing effort on what matters most: how far that access can be escalated.

Password spraying tests a small number of commonly used or organisationally predictable passwords against a large list of enumerated usernames, rather than exhaustively guessing many passwords against one account - a technique specifically designed to stay under account-lockout thresholds. In this engagement, the sprayed password matched the credentials of 189 separate accounts, including a Domain Administrator account. Because that single account already held the highest level of domain privilege, no further exploitation was required: the tester could immediately extract every credential in the domain.

LLMNR (Link-Local Multicast Name Resolution) and NBT-NS (NetBIOS Name Service) are legacy Windows protocols that let devices resolve hostnames on a local network when standard DNS lookups fail. Because they use unauthenticated broadcast requests, an attacker on the same network segment can respond to these requests, tricking the requesting machine into authenticating to the attacker's system and handing over an NTLM hash in the process. Despite being well-documented attack techniques for over a decade, both protocols remain enabled by default on many Windows environments, which is exactly what allowed credential capture in this engagement.

File shares are typically governed by broad access-control lists intended for document collaboration, not by the tighter, purpose-built access controls a secrets manager or password vault provides. When credentials, API keys or cloud tokens are saved to these shares - often for convenience during setup or troubleshooting - they inherit that broad access, becoming readable by any user with share permissions rather than only the systems or people that actually need them. In this engagement, exactly this pattern gave the testing team access to cloud, SaaS and database credentials entirely separate from the Active Directory domain itself, dramatically expanding the impact of the assessment.

Kerberoasting is a technique where any authenticated domain user requests Kerberos service tickets for accounts with registered Service Principal Names, then attempts to crack those tickets offline to recover the underlying account password. In this engagement, the exposed tickets belonged to machine accounts, which by default have long, randomly generated, regularly rotated passwords - making successful offline cracking highly unlikely under normal configurations. The finding was therefore rated Low severity, reflecting genuine risk to reconnaissance and attack-surface visibility rather than a realistic path to credential recovery, unless combined with legacy encryption misconfigurations.

The tunnel in this engagement was established using standard, widely available tooling (SSH with remote port forwarding), routed over an encrypted connection that resembles ordinary secure traffic rather than obviously malicious activity. Many endpoint security deployments focus detection on known-malicious file signatures and process behaviour rather than on the network-level patterns of unauthorized outbound tunneling - a detection gap this finding was specifically designed to surface. Closing it typically requires a combination of egress filtering, application allowlisting for networking utilities, and dedicated detection rules for anomalous encrypted outbound connections, rather than relying on endpoint tooling alone.

Based on patterns from this and similar engagements, ISECURION recommends a minimum password length of at least 14 characters for standard user accounts and 20 characters for privileged and administrative accounts, combined with a banned-password list aligned to current threat intelligence (blocking predictable organisational patterns, common substitutions and previously breached passwords), an increased password history to prevent short-cycle reuse, and mandatory multi-factor authentication for all privileged, administrative and remote-access accounts. Length and MFA together do far more to resist password spraying than complexity rules alone.

ISECURION recommends internal Active Directory penetration testing on at least an annual basis, with follow-up validation testing scheduled specifically after remediation of critical and high-severity findings, and additional testing triggered by any significant change to the directory structure, trust relationships, or major infrastructure migrations. Organisations in regulated sectors, or those handling particularly sensitive data, often benefit from a more frequent cadence combined with ongoing detection-focused exercises such as purple teaming.

Yes. In addition to serving organisations across major Indian cities - Bangalore, Mumbai, Delhi NCR, Noida, Chennai, Hyderabad, Pune, Kolkata, Ahmedabad and Kochi - ISECURION delivers internal network and Active Directory penetration testing for organisations in the United States, United Kingdom, the European Union, the GCC region, Singapore and Australia, with both on-site and remote-access delivery models available depending on the client's environment and constraints.

1. Treat P1 findings as immediate priorities: reset privileged credentials, eliminate confirmed password reuse, rotate exposed secrets, and lock down over-permissive file shares.
2. Ingest findings into a tracked risk register with named owners, target dates and acceptance criteria rather than leaving remediation informally distributed.
3. Disable legacy protocols (LLMNR, NBT-NS) via Group Policy and validate the change across the estate through post-deployment scanning.
4. Tune EDR and SIEM detection rules specifically for the techniques demonstrated - password spraying patterns, anomalous NTDS access, LLMNR poisoning indicators, and unexpected outbound tunneling.
5. Schedule a follow-up validation assessment once critical and high findings are remediated, to confirm closure rather than assuming remediation was effective.