Shells & Payloads: Detection & Prevention

Monitoring Active Shells

• Utilize the MITRE ATT&CK Framework to identify tactics and techniques:

  • Initial Access: Exploiting public-facing services (e.g., web apps, SMB).

  • Execution: Executing commands on the victim system via exploits, shells, or payloads.

  • Command & Control (C2): Maintaining interactive access, often over encrypted channels.

• Events to Monitor:

  • File uploads: Logs can reveal malicious file uploads; pair with AV/firewall for detection.

  • User anomalies: Look for unexpected CLI usage (e.g., whoami, SMB access).

  • Network traffic: Unusual patterns (e.g., port 4444, new sites, bulk requests). Use tools like SIEMs and NetFlow.

Establishing Network Visibility

• Maintain updated network topology diagrams using tools like NetBrain.

• Leverage Layer 7 firewalls for application-level traffic monitoring.

• Establish traffic baselines to spot deviations quickly.

• Use deep packet inspection to analyze cleartext and encrypted traffic.

End Device Protection

• Key Devices: Workstations, servers, printers, NAS, IoT devices.

• Ensure anti-virus and Windows Defender are active with firewalls enabled.

• Implement patch management to secure devices against exploits.

Mitigation Strategies

• Application Sandboxing: Limit damage from compromised apps.

• Least Privilege Access: Grant minimum permissions needed for tasks.

• Host Segmentation & Hardening: Place exposed systems (e.g., web servers) in a DMZ.

• Firewall Policies: Block unauthorized ports and traffic; enforce NAT to disrupt reverse shells.

• A defense-in-depth strategy incorporating monitoring, mitigation, and visibility strengthens security posture.