From Log Analysis to AD Compromise: Lessons from My First Real-World AD Pentest

Having spent years in web application and infrastructure vulnerability assessment, and eventually earning my OSCP, I assumed real-world penetration testing would follow the predictable patterns of lab environments.

However, a recent 5-week Active Directory (AD) pentesting project for a large enterprise was a major reality check.

In a hardened corporate network where patches are up to date and defensive telemetry (EDR, SIEM) is active, public exploits (CVEs) and Local Privilege Escalation (LPE) scripts were practically useless. Ultimately, compromising the Domain Controller (DC) required something different: an understanding of the overall network topology, real-time adaptation, and the ability to exploit structural flaws in the business architecture.

Here are the key technical and architectural insights I gathered from this project.

1. How SOC Experience Shaped My Offensive Strategy

Before pivoting to offensive security, I spent a year as a Security Operations Center (SOC) analyst, monitoring SIEM alerts and analyzing firewall rules. This defensive background proved to be a significant asset when executing attacks.

• Understanding Telemetry: Having analyzed how payloads trigger Yara rules and what system artifacts (like Windows Event ID 4688 for process creation) they leave behind, I was able to design my attacks to minimize noise.
• Prioritizing Stealth: Knowing that aggressive scanning or raw tool execution triggers immediate containment, I focused on minimizing my operational footprint and blending in with normal network traffic.

2. Levering Web Hacking Experience for Initial Access

Securing an initial foothold required leveraging my experience in enterprise web and API assessment.

• Attack Surface Analysis: The external attack surface was extremely narrow, and no initial credentials were provided. In manufacturing enterprises, internal employees and external vendors must share integrated systems for daily operations. Based on this profile, I targeted an externally exposed SRM (Supplier Relationship Management) system.
• The Foothold: I discovered a logical flaw in the SRM system that allowed unauthenticated access to the server scheduler. By creating, modifying, and executing a custom scheduler task under system privileges, I established our initial foothold into the internal network.

3. Navigating a Hardened Active Directory Environment

While OSCP prepared me for standard AD techniques like Kerberoasting and Pass-the-Hash, the client's actual network was heavily mitigated. Port scanning was rate-limited, and strict Group Policy Objects (GPOs) blocked access to LSASS memory, rendering standard credential dumping tools useless.

① User Enumeration and Password Spraying

With standard exploitation tools blocked by EDR, I targeted identity data.

• Using standard domain user privileges, I queried the Active Directory database to extract the list of all domain usernames.
• I filtered the list to isolate personal employee accounts and performed a slow, targeted Password Spraying attack designed to bypass lockout thresholds. This yielded our first set of valid employee credentials.

② Bypassing Isolated Authentication (SSO to AD)

The internal applications used a corporate Single Sign-On (SSO) system, while AD credentials only authenticated the VDI systems.

• I attempted Credential Stuffing on the SSO portal using the cracked AD password. Because of password reuse across different identity providers, I successfully compromised the employee's SSO account.
• This granted access to the internal network and VDI systems, allowing me to map the internal topology. Using the gathered credentials and password patterns, I performed an N:M spraying attack against Domain Admin accounts and successfully escalated privileges.

③ Direct DC Connection and Gateway Bypass

Although I obtained Domain Admin rights, the Domain Controller (DC) had strict egress filtering, blocking any outbound reverse shells. Additionally, RDP (3389) access to the DC was restricted behind a secure gateway jump box.

• To bypass the gateway, I used WMI (Windows Management Instrumentation) to command the DC to open a bind shell listener on a high-numbered port (in the 50,000s range).
• I then commanded the DC to port-forward this high port to its local port 3389 (RDP).
• Since internal high-port communication between server zones was not blocked by firewall rules, I bypassed the secure gateway and connected directly to the DC via RDP over the 50,000s port.

4. Red Teaming vs. Vulnerability Assessment

This project highlighted the difference between checklist-based vulnerability assessment and target-oriented red teaming.

Traditional vulnerability assessments focus on finding individual critical bugs like SQL Injection or Remote Code Execution (RCE). In contrast, during this red team simulation, we did not find a single high-severity CVE. Instead, we compromised the entire domain by chaining minor configuration flaws, logical bugs, and user habits.

Additionally, while our custom C2 loader successfully executed without triggering EDR alerts, it was ultimately blocked by the egress firewall. This highlighted that host-level evasion is only half the battle; understanding and bypassing network-level egress filtering is equally critical. This realization has shifted my research focus toward asynchronous agents and alternative transport protocols (like DNS or ICMP tunneling).

5. Conclusion & Next Steps

My first real-world AD pentest demonstrated how my background in SOC operations, web security, and OSCP methodology converged to solve a complex puzzle.

I learned that offensive security is less about running exploits and more about understanding network architecture and adapting in real-time to design bypasses. Moving forward, I plan to focus my research on advanced EDR evasion techniques and developing robust custom C2 infrastructures capable of bypassing strict egress environments.