M1037 Filter Network Traffic

Employ network appliances and endpoint software to filter ingress, egress, and lateral network traffic. This includes protocol-based filtering, enforcing firewall rules, and blocking or restricting traffic based on predefined conditions to limit adversary movement and data exfiltration. This mitigation can be implemented through the following measures: Ingress Traffic Filtering: • Use Case: Configure network firewalls to allow traffic only from authorized IP addresses to public-facing servers. • Implementation: Limit SSH (port 22) and RDP (port 3389) traffic to specific IP ranges. Egress Traffic Filtering: • Use Case: Use firewalls or endpoint security software to block unauthorized outbound traffic to prevent data exfiltration and command-and-control (C2) communications. • Implementation: Block outbound traffic to known malicious IPs or regions where communication is unexpected. Protocol-Based Filtering: • Use Case: Restrict the use of specific protocols that are commonly abused by adversaries, such as SMB, RPC, or Telnet, based on business needs. • Implementation: Disable SMBv1 on endpoints to prevent exploits like EternalBlue. Network Segmentation: • Use Case: Create network segments for critical systems and restrict communication between segments unless explicitly authorized. • Implementation: Implement VLANs to isolate IoT devices or guest networks from core business systems. Application Layer Filtering: • Use Case: Use proxy servers or Web Application Firewalls (WAFs) to inspect and block malicious HTTP/S traffic. • Implementation: Configure a WAF to block SQL injection attempts or other web application exploitation techniques.