Full Report
In the last blog of our defense evasion series, we'll cover granular advice for monitoring and detecting defense evasion.
Analysis Summary
# Best Practices: Detecting and Mitigating Defense Evasion
## Overview
These practices address the methods adversaries use to hide their presence, bypass security controls, and maintain persistence within a network. Rather than relying solely on automated tools, these guidelines focus on a "proactive security" mindset—combining technical hardening with active monitoring to catch advanced intrusions that security products might miss.
## Key Recommendations
### Immediate Actions
1. **Inventory & Visibility:** Create an immediate inventory of all network-connected machines and identify those exposed to the internet.
2. **MFA Enforcement:** Roll out Multi-Factor Authentication (MFA) across all user accounts, starting with administrative and remote access portals.
3. **Audit Active Directory:** Perform a basic audit of AD permissions to identify "low-hanging fruit" such as excessive admin privileges or legacy service accounts.
4. **Baseline Backup Integrity:** Verify that backup solutions are functional and stored in an immutable or offsite location to prevent ransomware encryption.
### Short-term Improvements (1-3 months)
1. **Patch Management Lifecycle:** Establish a formal schedule for patching operating systems and third-party applications based on vulnerability severity.
2. **Enhanced Logging:** Configure granular logging for process creation (with command-line arguments) and PowerShell activity (Script Block Logging).
3. **Evasion Monitoring:** Set up alerts for common defense evasion indicators, such as clearing event logs, modification of registry keys related to security software, or attempts to add AV exclusions.
4. **Honeypots/Honey-Tokens:** Implement simple "canary" files or accounts to distract and detect adversaries early in the kill chain.
### Long-term Strategy (3+ months)
1. **Threat Modeling:** Move beyond generic threats to model risks based on your specific business functions (e.g., disgruntled employees vs. supply chain attacks).
2. **Continuous Testing:** Implement regular efficacy testing of the security stack, including simulated attacks to ensure alerts actually trigger.
3. **Proactive Threat Hunting:** Dedicate time for manual "hunting" within logs rather than waiting for automated alerts to fire.
4. **Zero Trust Architecture:** (Where applicable) Begin moving toward a least-privilege, identity-centric model for network access.
## Implementation Guidance
### For Small Organizations
- **Focus:** Hygiene over "flashy" tools.
- Prioritize automated patching and MFA. Use built-in OS security features (like Windows Defender) and ensure they are managed and monitored rather than just "installed."
### For Medium Organizations
- **Focus:** Visibility and Response.
- Implement centralized log management (SIEM or specialized log aggregator). Focus on monitoring data exfiltration points and abnormal account behavior.
### For Large Enterprises
- **Focus:** Red Teaming and Resilience.
- Conduct regular penetration tests that specifically target defense evasion capabilities. Focus on hardening Active Directory to mitigate the 80% of common attack vectors.
## Configuration Examples
*While the article emphasizes strategy, the following technical focuses are derived from the recommendations:*
- **PowerShell Security:** `Set-ItemProperty -Path HKLM:\Software\Policies\Microsoft\Windows\PowerShell\ScriptBlockLogging -Name EnableScriptBlockLogging -Value 1`
- **Audit Policy:** Enable "Audit Process Creation" and "Include command line in process creation events" via Group Policy (GPO).
- **Registry Monitoring:** Watch for changes to `HKLM\SOFTWARE\Microsoft\Windows Defender\Exclusions`.
## Compliance Alignment
- **CIS Controls:** Specifically Controls 4 (Secure Configuration), 5 (Account Management), and 8 (Audit Log Management).
- **NIST CSF:** Aligns with the **Protect** (MFA, Patching) and **Detect** (Continuous Monitoring) functions.
- **MITRE ATT&CK:** Directly addresses the **Defense Evasion (TA0005)** tactic.
## Common Pitfalls to Avoid
- **"Product-Only" Security:** Believing a single expensive tool (AI/ML) replaces the need for internal security expertise and hardening.
- **Blind Trust:** Assuming that because a security product is active, it cannot be bypassed or disabled by an attacker.
- **Ignoring the Mundane:** Focusing on sophisticated APTs while neglecting basic vulnerabilities like unpatched internet-facing servers.
- **Static "Risk Acceptance":** Accepting risks without a documented, informed decision-making process.
## Resources
- **MITRE ATT&CK Framework:** [https://attack.mitre.org/tactics/TA0005/](https://attack.mitre.org/tactics/TA0005/)
- **Trimarc Security (AD Hardening):** [https://www.trimarcsecurity.com/](https://www.trimarcsecurity.com/)
- **SpecterOps Evasion Classifications:** [https://posts.specterops.io/evadere-classifications-8851a429c94b](https://posts.specterops.io/evadere-classifications-8851a429c94b)