Command and Control Assessment

Description: Forensically investigating Command and Control (C&C) techniques on workstations and server systems involves identifying how an attacker communicates with compromised systems to control them remotely and potentially exfiltrate data. This process is critical for understanding the scope of an attack and mitigating further risks.

1. Understanding Common C&C Techniques

• Direct Connections: Using tools like remote desktop, SSH, or VNC.

• HTTP/HTTPS-Based Communication: Often disguised as normal web traffic.

• DNS-Based Communication: Using DNS queries to send commands or exfiltrate data.

• Use of Proxy Servers: To route and obfuscate the traffic.

• Social Media and Cloud Services: Utilising popular platforms to disguise communication.

2. Data Collection and Preservation

• Forensic Imaging: Create exact images of affected systems using tools like FTK Imager or dd.

• Memory Capture: Use tools like Magnet RAM Capture or WinPmem for capturing volatile memory, which may contain remnants of C&C communication.

• Log Collection: Gather network logs, firewall logs, DNS logs, system logs, and web proxy logs.

3. Network Traffic Analysis

• Traffic Capture and Analysis: Use tools like Wireshark or tcpdump to analyse network traffic for unusual patterns, especially outbound connections to unknown IPs or domains.

• Protocol Analysis: Look for anomalies in standard protocols (HTTP, DNS, etc.) that could indicate C&C activities.

• The decryption of Traffic: Where possible, decrypt encrypted network traffic to inspect the contents for command and control communication.

4. DNS Query Analysis

• Logs Review: Examine DNS query logs for frequent or irregular requests to uncommon domains, which could indicate DNS tunnelling.

5. Firewall and Proxy Logs Analysis

• Outbound Traffic: Check for any rules or logs that show unusual outbound traffic, especially traffic bypassing standard network egress points.

6. Endpoint Analysis

• Running Processes: Analyse running processes and their network activity for signs of C&C communications.

• Startup Items and Scheduled Tasks: Check for persistence mechanisms that may initiate C&C communication upon system restart.

• Host-based Intrusion Detection Systems: Review alerts and logs for signs of C&C behaviour.

7. Malware Analysis (if applicable)

• Static and Dynamic Analysis: If malware is identified, perform static and dynamic analysis to understand its communication mechanisms.

• Reverse Engineering: Reverse-engineering malware may reveal built-in C&C domains or IP addresses.

8. Use of Specialised Forensic Tools

• Forensic Suites: Tools like EnCase, Autopsy, or X-Ways for comprehensive system analysis.

• Network Analysis Tools: Wireshark, Tcpdump, NetWitness, and NetworkMiner for network traffic analysis.

9. Documentation and Reporting

• Detailed Documentation: Record all methodologies, findings, and tools used.

• Forensic Report: Compile a comprehensive report detailing the C&C investigation, findings, and implications.

10. Post-Investigation Actions

• Mitigation and Remediation: Implement measures to disrupt the C&C channels and prevent further unauthorised access.

• Recovery and Notifications: Restore systems and notify relevant stakeholders per organisational and legal requirements.

11. Tools and Techniques

• Digital Forensics:

  • Specialised tools for evidence collection and analysis:

    • OpenText EnCase Forensics (commercial tool)

    • FTK (Forensic Toolkit)

    • Volatility (memory forensics)

    • Autopsy (open-source)

    • Cyber Triage (commercial tool)

    • Binalyze AIR (commercial tool)

    • Belkasoft (commercial tool)

    • Oxygen Forensics (commercial tool)

    • X-ways Forensics (commercial tool)

    • The Sleuth Kit (open-source tool)

    • Eric Zimmerman Tools (open-source tool)

  • Techniques include timeline analysis, file recovery, and reverse engineering.

• Incident Response:

  • Tools for monitoring, containment, and eradication:

    • SIEM (Splunk, QRadar, Microsoft Sentinel, Sumo Logic, Graylog, Elastic Security, LogRhythm, Datadog, Exabeam)

    • EDR (CrowdStrike, SentinelOne, Defender for Endpoint, Cortex XDR, FortiEDR)

    • Firewalls and IDS/IPS systems

  • Techniques include log analysis, threat containment, and system restoration.

12. Key Considerations

• Legal Compliance: Ensure the investigation complies with relevant laws and regulations, especially when decrypting traffic.

• Chain of Custody: Maintain an accurate chain of custody for all forensic evidence.

• Data Confidentiality: Handle all data securely, maintaining its confidentiality and integrity.

C&C investigation requires a multi-faceted approach, combining network analysis, endpoint inspection, and potentially malware analysis to fully understand the attacker's methods and impact. Tailoring the investigation to the specifics of the incident and the environment is crucial.