Traffic Signaling:  Простукивание портов

Mafalda can use port-knocking to authenticate itself to another implant called Cryshell to establish an indirect connection to the C2 server.(Citation: SentinelLabs Metador Sept 2022)(Citation: SentinelLabs Metador Technical Appendix Sept 2022)

PROMETHIUM has used a script that configures the knockd service and firewall to only accept C2 connections from systems that use a specified sequence of knock ports.(Citation: Bitdefender StrongPity June 2020)

cd00r can monitor for a single TCP-SYN packet to be sent in series to a configurable set of ports (200, 80, 22, 53 and 3 in the original code) before opening a port for communication.(Citation: Hartrell cd00r 2002)(Citation: Lumen J-Magic JAN 2025)

metaMain has authenticated itself to a different implant, Cryshell, through a port knocking and handshake procedure.(Citation: SentinelLabs Metador Sept 2022)

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.