Internal ethical hacking: how far an attacker can get inside your network

By the QuantumSec team

Most companies invest in protecting the perimeter, but once an attacker gets in — through phishing, a leaked account, a malicious insider — few really know how far they could get. Internal ethical hacking simulates exactly that scenario: an attacker who already has a foothold inside the network. This guide explains what it assesses and why Active Directory is almost always the final target.

What internal ethical hacking is, and why it matters even with a well-protected perimeter

Insider threats and successful phishing are, in practice, the most common entry vectors in real incidents, and neither depends on a misconfigured perimeter. Once inside, if the network isn't segmented and Active Directory isn't hardened, an attacker can move laterally, escalate privileges and access critical systems for weeks without being detected. Internal ethical hacking answers the question a well-protected perimeter doesn't: what happens if someone is already inside?

Active Directory: the primary target of any internal attacker

Almost every internal attack path ends at Active Directory, because it controls permissions across the entire organization. The most common techniques include Kerberoasting (extracting and offline-cracking service tickets from privileged accounts), AS-REP Roasting (against accounts without Kerberos pre-authentication), and abuse of misconfigured ACLs that let a low-privilege user modify permissions on more sensitive accounts. Tools like BloodHound automatically map these escalation paths, which in large networks are far more numerous than most IT teams assume.

Lateral movement and privilege escalation: the real techniques

Pass-the-hash and pass-the-ticket let an attacker reuse stolen credentials (hashes or Kerberos tickets) without ever knowing the plaintext password. NTLM relay abuses legacy authentication protocols to impersonate another machine on the network. And exploiting reused or weak service account credentials is, by far, the most common path to a domain admin account. Each of these techniques is tested in a controlled way to document the exact path a real attacker would follow.

What this service adds over a traditional network pentest

A network pentest assesses configurations and point-in-time vulnerabilities. Internal ethical hacking goes a step further: it starts from an assumed entry point (typically a standard domain user) and documents the full attack chain up to maximum possible impact, classified under MITRE ATT&CK Enterprise. The result isn't a list of isolated flaws — it's a map of how those flaws combine in practice to compromise the whole organization.

FAQ

What starting point is used for internal ethical hacking?

We typically simulate a standard domain user with no special privileges — the most realistic scenario (an employee compromised by phishing, or an attacker with initial access). It's also possible to start from physical network access or an unprivileged account on a specific machine, depending on the agreed scope.

Can the test affect production systems?

We coordinate every test with your IT team. The more invasive techniques, like modifying Active Directory objects, are run only with explicit authorization and during agreed windows. The goal is to demonstrate risk, not cause disruption.

How often should this assessment be repeated?

At least once a year, and always after significant changes to Active Directory or network structure (mergers, new offices, migrations). If you are subject to NIS2 or ISO 27001, the regulation may require a specific cadence.