Think your business is secure? Why assumed breach testing is the real test

It’s widely recognised that organisations worldwide face relentless external cyber threats from a variety of threat actors, but far less consideration is given to threats that may be coming from inside an organisation itself.

Insider threats can originate from a variety of sources, including malicious or disgruntled employees, or even external attackers who have compromised internal users through phishing or exploiting internal vulnerabilities. Furthermore, and more significantly, depending on the specific nature of the attack or breach, some threat actors can maintain prolonged access to any compromised internal systems, giving them endless opportunities to explore the internal networks and any valuable assets.

Why an assumed breach or rogue user exercise is essential

This is where advanced internal security testing such as an assumed breach, or rogue user exercise would come into play, unlike other forms of internal penetration test, including:

• where the assessment could either be performed from a fully unauthenticated perspective, simulating an attacker who had managed to simply connect into the network and “see what they could see”, investigating and attacking as much as possible in the time available.
• scanning the organisation’s networks and assets for patching and misconfigurations from an administrative perspective.

An assumed breach or rogue user assessment focuses on what an internal rogue user with standard domain user privileges could do within the network, rather than patching levels or other similar misconfigurations on various devices.

Such an assessment should consider multiple possible scenarios, as described above, particularly in terms of initial access, but the overall final objective is generally the same: Can such a rogue internal user, such as a disgruntled employee, or other threat actor who has managed to compromise the network through other means and can maintain their access, elevate their privileges, access sensitive data, or otherwise compromise the network further in some meaningful way?

How is an assumed breach assessment different from an unauthenticated internal penetration test?

While an assumed breach assessment can sometimes be considered an extension of a completely unauthenticated Internal penetration test (where an attacker simply plugs in an unknown laptop, or other remote device and begins exploring with no credentials), the boundary between these usually lies in whether an attacker can gain any form of authenticated foothold into the network, from an initial unauthenticated perspective. Since this is often a time-consuming practice, an assumed breach exercise can be regarded as a cost-effective middle ground, especially when budgets are tighter but organisations want to evaluate real internal risks.

What’s the difference between Red Team vs. assumed breach?

Some may ask how and where this differs from a Red Team engagement. The answer to this lies in the scope (breadth) and noise generated from such a test:

• Red Teams generally assess a broader area of potential entry points, combining multiple forms or otherwise different tests into one engagement (OSINT, Social-Engineering, External Infrastructure, Web App, VPN etc), but also generally aim to be “quieter”, flying under the radar to avoid detection for as long as possible. However, this attempted detection avoidance normally means that things can take longer, hence Red Team engagements generally being spread over a longer period.
• Assumed breach/ rogue user assessments on the other hand are still conducted within a much smaller commercial time window and need to be “louder” to still ensure good coverage.

What’s tested on an assumed breach assessment?

The type of testing you can do with a standard domain or low-privileged user account depends on how you want to simulate the attack, and ultimately whether there are any particular objectives to be attained. If the test is run from an organisation-owned device, such as a corporate laptop connected to the VPN, security policies might limit what the attacker can do. But if the test is done from an attacker-owned device with full admin rights, connected via VPN, this provides a broader and more accurate assessment - especially if this approach can be consistently repeated.

Assessments typically examine:

• Number of users present on the domain
• Domain’s password policy
• The presence of any accounts whose sensitive password data may be retrievable by other domain users, via the design of Active Directory
• Whether any such accounts are highly privileged, and/or whose plaintext passwords are retrievable (crackable) within a reasonable time
• Quantity and identities of domain admin accounts
• Examination of any networks shares available, and whether any sensitive data is contained within

Real-world lessons from insider-related attacks

Many organisations have experienced domain compromises due to misconfigurations or not following best practice - allowing even standard domain users to escalate privileges and take control of entire networks. These vulnerabilities are prevalent both on-premises and via virtual machines and networks in the cloud, emphasising that internal security is as vital as external defences.

Ready to strengthen your internal security?

An assumed breach or rogue user assessment provides invaluable insight into how well your defences hold up against internal threats. By simulating real-world scenarios, we identify weaknesses before malicious insiders or compromised accounts do.

If you would like to learn more about how we identify vulnerabilities with our range of services, including penetration testing, get in touch.

About the author

Chris Watt has been in the penetration testing arena for over 12 years, specialising in web application and API security. For the last few years he has been steadily branching out into other types of security, including advanced infrastructure and mobile app testing.