The challenge facing security leaders is securing an environment where failure is not an option. Relying on traditional security postures such as endpoint detection and response (EDR) to track threats that enter a network is fundamentally risky and contributes significantly to the $5 trillion annual cost of cybercrime.
Zero Trust fundamentally changes this approach, moving from responding to symptoms to proactively solving the root problem. Application control, the ability to precisely define what software is allowed to run, is the cornerstone of this strategy. However, even once an application is trusted, it can still be exploited. This is where ThreatLocker Ringfencing™ (fine-grained application containment) becomes essential, enforcing the ultimate standard of least privilege for all authorized applications.
Defining ring fencing: security beyond whitelisting
Ring fencing is an advanced containment strategy applied to applications that are already approved to run. While whitelisting ensures a basic default deny attitude to all unknown software, ring fencing further restricts the functionality of allowed software. It works by specifying exactly what an application can access, such as files, registry keys, network resources, and other applications and processes.
This granular control is critical because attackers frequently exploit legitimate, approved software to bypass security controls. This is a technique commonly referred to as “residency.” Uncontained applications such as productivity suites and scripting tools can be weaponized to spawn dangerous child processes (such as PowerShell or Command Prompt) or communicate with unauthorized external servers.
Security Matters: Stopping Overreach
Without effective containment, security teams are left with a wide range of attack vectors that can directly lead to high-impact incidents.
Lateral movement mitigation: Ring fencing isolates application behavior and impedes a compromised process’ ability to move across the network. You can set policies to limit outbound network traffic. This helps stop large-scale attacks that rely on servers asking malicious endpoints for instructions. Inclusion of high-risk applications: A key use case is mitigating the risks associated with traditional files or scripts such as Office macros. When you apply containment, applications such as Word and Excel are restricted from starting high-risk scripting engines such as PowerShell or accessing high-risk directories, even if required by departments such as finance. Preventing data exfiltration and encryption: Containment policies can restrict an application’s ability to read or write to monitored sensitive paths (such as document folders or backup directories), effectively blocking attempts to exfiltrate large amounts of data and preventing ransomware from encrypting files outside of the specified scope.
Ringfencing inherently supports compliance goals by ensuring that all applications operate with exactly the privileges they really need and by aligning security efforts with best practice standards such as CIS controls.
Mechanics: How granular containment works
Ring-fencing policies comprehensively control multiple vectors of an application’s behavior and serve as a second layer of defense after it is allowed to run.
Policies determine whether an application can access certain files or folders or modify the system registry. Most importantly, manage interprocess communication (IPC) to ensure that authorized applications cannot interact with or spawn unauthorized child processes. For example, ring fencing blocks Word from launching PowerShell and other unauthorized child processes.
Implementing application containment
Implementing ring-fencing requires a disciplined, gradual implementation focused on avoiding operational disruption and political influence.
Establishing a baseline
Implementation begins by deploying monitoring agents to establish visibility. Agents must first be introduced to a small test group or independent test organization (often affectionately referred to as guinea pigs) to monitor activity. In this initial learning mode, the system logs all execution, promotion, and network activity without blocking anything.
Simulation and forcing
Before securing policies, teams should leverage unified auditing to run simulations (simulated denials). This pre-emptive audit shows exactly what actions will be blocked if the new policy goes into effect, allowing security professionals to proactively make necessary exceptions and avoid losing IT support.
Typically, ring-fencing policies are created and applied first for applications identified as high-risk, such as PowerShell, Command Prompt, Registry Editor, and 7-Zip, because they have a high likelihood of being weaponized. Teams must ensure that they are properly tested before moving to a safe and enforced state.
Scaling and refinement
Once the policy is validated in a test environment, the deployment is scaled up across the organization in stages, typically starting with easy successes and slowly moving toward the most difficult groups. Policies should be continually reviewed and improved, including periodically deleting unused policies to reduce administrative complexity.
Strategic development and best practices
To maximize the benefits of application containment while minimizing user friction, leaders must follow proven strategies.
Start small and gradually: Always apply new ring-fencing policies to non-critical test groups first. Avoid solving all business problems at once. Tackle the most dangerous software first (such as Russian remote access tools) and delay political decisions (such as blocking games) until a later stage. Continuous monitoring: Regularly review integration audits and check for simulated denials to ensure legitimate functionality is not compromised before securing policies. Combined control: Ring fencing is most effective when combined with application allow lists (deny by default). It should also be combined with Storage Control to protect critical data and prevent mass data loss or leakage. Prioritize configuration checks: Leverage automated tools such as Configuration Defense (DAC) to ensure that ring-fencing and other security measures are properly configured across all endpoints and highlight where settings may be in monitor-only mode.
Outcomes and organizational benefits
By implementing Ringfencing, organizations move from a reactive model where highly paid cybersecurity professionals spend their time chasing down alerts to a proactive, hardened architecture.
This approach provides significant value beyond mere security.
Operational efficiency: Application controls significantly reduce security operations center (SOC) alerts (up to 90% in some cases), reducing alert fatigue and significantly saving time and resources. Increased security: Prevent abuse of trusted programs, contain threats, and make it as difficult as possible for cybercriminals. Business value: Minimize application overload without disrupting business-critical workflows, such as those required by finance departments for traditional macros.
Ultimately, Ringfencing strengthens the idea of Zero Trust, ensuring that all applications, users, and devices operate strictly within their required capabilities, making detection and response a true backup plan rather than the primary defense.
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