Full Report
Assume nothing, trust nothing—and secure everything
Analysis Summary
# Best Practices: Implementing a Positive Security Model through Application Control
## Overview
These practices focus on transitioning security defenses from reliance on traditional *negative security models* (denylisting known threats) to a proactive *positive security model* (allowlisting and executing only trusted applications and processes). This approach is crucial for mitigating zero-day threats, ransomware, and attacks targeting overlooked or legacy assets.
## Key Recommendations
### Immediate Actions
1. **Inventory All Running Software:** Immediately identify and document all applications and processes currently executing across critical assets (on-premises, cloud, fixed-function devices) to establish a baseline for trust definition.
2. **Initiate Trust Establishment:** Begin the process of defining and establishing trust criteria for essential applications and processes, prioritizing critical systems and public-facing assets.
3. **Enforce Basic Registry Protection:** Immediately implement centralized controls to block unauthorized modifications to critical Windows registry keys on high-value systems.
### Short-term Improvements (1-3 months)
1. **Deploy Baseline Allowlist:** Configure and enforce a positive security model (allowlisting) across a pilot group of non-production or lower-risk systems, ensuring only explicitly trusted applications are permitted to run.
2. **Integrate Trust Sources:** Integrate mechanisms like **cloud trust data**, **trusted publisher information**, and **custom initial allowlist rules** to speed up the establishment of the baseline and reduce manual effort.
3. **Implement Memory Protection:** Activate and configure memory protection features to control access and alterations to running processes, specifically targeting defense against common in-memory attacks.
### Long-term Strategy (3+ months)
1. **Comprehensive Rollout:** Systematically expand the positive security model enforcement across the entire enterprise environment, including segmented networks, legacy systems, and cloud workloads.
2. **Establish Continuous File Integrity Monitoring (FIM):** Configure FIM across critical file systems and registry locations, establishing an automated rejection policy for any detected tampering or unauthorized file/registry modifications.
3. **Define Granular Device Control Policies:** Develop and enforce explicit policies governing data transfers between systems and external storage devices (USB drives, external media), effectively limiting potential data exfiltration vectors.
4. **Secure Legacy and Air-Gapped Systems:** Utilize the application control capability to lock down fixed-function devices, end-of-life (EOL) operating systems, and highly sensitive air-gapped environments using strict allowlists, as traditional defenses often fail here.
## Implementation Guidance
### For Small Organizations
- **Prioritize Critical Endpoints:** Focus initial deployment on endpoints handling sensitive data or those most exposed (e.g., administrative workstations, critical servers).
- **Leverage Cloud Trust:** Maximize the use of pre-vetted cloud-based trust lists to minimize the initial effort required to build the allowlist from scratch.
### For Medium Organizations
- **Phased Rollout by Business Unit:** Implement deployment wave-by-wave, aligning with business unit criticality to manage integration risks and operational disruptions.
- **Integrate with Inventory Tools:** Connect the application control solution with existing Configuration Management Database (CMDB) or asset inventory tools to ensure configuration drift is flagged immediately.
### For Large Enterprises
- **Establish Governance Structure:** Create a formal review board responsible for approving new software and changes to the established trust baseline.
- **Automate Monitoring and Reporting:** Implement robust monitoring leveraging the solution's capabilities to identify unauthorized software attempts, generating prioritized alerts for security operations center (SOC) staff.
- **Address Cloud Deployment Gaps:** Specifically configure controls to manage application execution within public and private cloud environments, ensuring consistency between on-premises and cloud assets.
## Configuration Examples
*Note: Specific vendor syntax is omitted, but the required control configuration components are listed.*
1. **Trust Configuration:** Explicitly define allowed applications using **Publisher Hash/Certificate** approval alongside **Pre-defined Cloud Trust Databases**.
2. **File Integrity Monitoring (FIM) Setup:** Configure FIM scopes to monitor key directories (e.g., `%SystemRoot%\System32`, application specific folders) and critical **Registry Hives** (e.g., HKEY\_LOCAL\_MACHINE\SOFTWARE).
3. **Device Control Settings:** Configure policy to **Block** all writes to external mass storage devices by default, with exceptions granted only via documented, temporary administrative exceptions.
## Compliance Alignment
- **NIST CSF:** Addresses Protect Function (PR.IP - Identify Assets; PR.PT - Protective Technology).
- **ISO/IEC 27001:** Aligns with Annex A controls related to access control and secure system engineering (A.9, A.14).
- **CIS Controls:** Directly supports Critical Controls such as **CIS Control 1: Inventory and Control of Hardware Assets** and **CIS Control 2: Inventory and Control of Software Assets**, and serves as a strong preventative measure equivalent to **Control 17: Application Software Security**.
## Common Pitfalls to Avoid
- **Relying Solely on Denylisting:** Continuously assuming legacy antivirus or signature-based tools offer sufficient protection against unknown or fileless attacks.
- **Skipping Comprehensive Inventories:** Attempting to deploy a positive security model without a complete and accurate understanding of what *should* be running, leading to business service disruption.
- **Ignoring EOL/Legacy Systems:** Assuming compliance or application control is only necessary for modern operating systems; these forgotten assets are prime targets for exploitation.
- **Inconsistent Policy Enforcement:** Applying developer or test policies to production environments, allowing unnecessary software execution pathways.
## Resources
- Framework documentation outlining the shift from reactive to proactive security posture.
- Vendor documentation detailing integration points for leveraging **Cloud Trust** verification services.
- Guides for auditing **Registry Protection** effectiveness across Windows environments.