Zerologon scored a perfect 10 CVSS score. Threats rating a perfect 10 are easy to execute and have deep-reaching impact. Fortunately, they aren’t frequent, especially in prominent software brands such as Windows. Still, organizations that perpetually lag when it comes to patching become prime targets for cybercriminals. Flaws like Zerologon are rare, but there’s no reason to assume that the next attack will not be using a perfect 10 CVSS vulnerability, this time a zero-day.
Zerologon: Unexpected squall
Zerologon escalates a domain user beyond their current role and permissions to a Windows Domain Administrator. This vulnerability is trivially easy to exploit. While it seems that the most obvious threat is a disgruntled insider, attackers may target any average user. The most significant risk comes from a user with an already compromised system.
In this scenario, a bad actor has already taken over an end user’s system but is constrained only to their current level of access. By executing this exploit, the bad actor can break out of their existing permissions box. This attack grants them the proverbial keys to the kingdom in a Windows domain to access whatever Windows-based devices they wish.
Part of why Zerologon is problematic is that many organizations rely on Windows as an authoritative identity for a domain. To save time, they promote their Windows Domain Administrators to an Administrator role throughout the organizational IT ecosystem and assign bulk permissions, rather than adding them individually. This method eases administration by removing the need to update the access permissions frequently as these users change jobs. This practice violates the principle of least privilege, leaving an opening for anyone with a Windows Domain Administrator role to exercise broad-reaching access rights beyond what they require to fulfill the role.
Beware of sharks
Advanced preparation for attacks like these requires a fundamental paradigm shift in organizational boundary definitions away from a legacy mentality to a more modern cybersecurity mindset. The traditional castle model assumes all threats remain outside the firewall boundary and trust everything either natively internal or connected via VPN to some degree.
Modern cybersecurity professionals understand the advantage of controls like zero standing privilege (ZSP), which authorizes no one and requires that each user request access and evaluation before granting privileged access. Think of it much like the security check at an airport. To get in, everyone —passenger, pilot, even store staff— needs to be inspected, prove they belong and have nothing questionable in their possession.
This continual re-certification prevents users from gaining access once they’ve experienced an event that alters their eligibility, such as leaving the organization or changing positions. Checking permissions before approving them ensures only those who currently require a resource can access it.
My hero zero (standing privilege)
Implementing the design concept of zero standing privilege is crucial to hardening against privilege escalation attacks, as it removes the administrator’s vast amounts of standing power and access. Users acquire these rights for a limited period and only on an as-needed basis. This Just-In-Time (JIT) method of provisioning creates a better access review process. Requests are either granted time-bound access or flagged for escalation to a human approver, ensuring automation oversight.
An essential component of zero standing privilege is avoiding super-user roles and access. Old school practitioners may find it odd and question the impact on daily administrative tasks that keep the ecosystem running. Users manage these tasks through heavily logged time-limited permission assignments. Reliable user behavior analytics, combined with risk-based privileged access management (PAM) and machine learning supported log analysis, offers organizations better contextual identity information. Understanding how their privileged access is leveraged and identifying access misuse before it takes root is vital to preventing a breach.
Peering into the depths
To even start with zero standing privilege, an organization must understand what assets they consider privileged. The categorization of digital assets begins the process. The next step is assigning ownership of these resources. Doing this allows organizations to configure the PAM software to accommodate the policies and access rules defined organizationally, ensuring access rules meet governance and compliance requirements.
The PAM solution requires in-depth visibility of each individual’s full access across all cloud and SaaS environments, as well as throughout the internal IT infrastructure. This information improves the identification of toxic combinations, where granted permissions create compliance issues such as segregation of duties (SoD) violations.
AI & UEBA to the rescue
Zero standing privilege generates a large number of user logs and behavioral information over time. Manual log review becomes unsustainable very quickly. Leveraging the power of AI and machine learning to derive intelligent analytics allows organizations to identify risky behaviors and locate potential breaches far faster than human users.
Integration of a user and entity behavior analytics (UEBA) software establishes baselines of behavior, triggering alerts when deviations occur. UEBA systems detect insider threats and advanced persistent threats (APTs) while generating contextual identity information.
UEBA systems track all behavior linked back to an entity and identify anomalous behaviors such as spikes in access requests, requesting access to data that would typically not be allowed for that user’s roles, or systematically accessing numerous items. Contextual information helps organizations identifying situations that might indicate a breach or point to unauthorized exfiltration of data.
Your compass points to ZTA
Protecting against privilege escalation threats requires more than merely staying up to date on patches. Part of stopping attacks like Zerologon is to re-imagine how security is architected in an organization. Centering identity as the new security perimeter and implementing zero standing privilege are essential to the foundation of a security model known as zero trust architecture (ZTA).
Zero trust architecture has existed for a while in the corporate world. It is gaining attention from the public sector since NIST’s recent approval of SP-207 outlined ZTA and how to leverage it for the government agencies. NIST’s sanctification of ZTA opened the doors for government entities and civilian contractors to incorporate it into their security model. Taking this route helps to close the privilege escalation pathway providing your organization a secure harbor in the event of another cybersecurity perfect storm.