Practical Threat Hunting Using Known IOC IPs

Understanding IOCs

Indicators of Compromise (IOCs) are pieces of forensic data that suggest potential malicious activity. They include IP addresses, domain names, file hashes, URLs, and email addresses. IP addresses, in particular, can reveal direct evidence of malicious connections, making them crucial in threat hunting.

The Role of IOC IPs in Threat Hunting

IOC IP addresses are key markers in identifying malicious activity. They can be sourced from threat intelligence feeds, incident logs, and research reports. By using IOC IPs, security teams can:

1. Detect Malicious Activity: Identify and trace connections to known malicious IPs.
2. Correlate Events: Link separate events across the network to a single attack.
3. Implement Preventive Measures: Block known threats associated with these IPs.

Practical Steps in Threat Hunting Using IOC IPs

1. Collection of IOC IPs

Start by gathering known malicious IP addresses from reliable sources. For this example, we will use a few well-documented malicious IPs:

- 192.168.1.100 (Placeholder for a known malware server)
- 203.0.113.50 (Placeholder for a known command and control server)
- 198.51.100.25 (Placeholder for a known phishing site)

Sources for these IPs can include:
- Threat Intelligence Feeds: Continuous updates from vendors like AlienVault, IBM X-Force, or open-source lists.
- Internal Logs: Data from previous incidents within your organization.
- Open Source Intelligence (OSINT): Publicly available databases and security forums.

2. Integrating IOC IPs into SIEM

Next, integrate these IOC IPs into your Security Information and Event Management (SIEM) system. Tools like Splunk, ArcSight, or QRadar can be configured to monitor for traffic involving these IP addresses.

3. Network Traffic Analysis

Analyze your network traffic for any signs of communication with these IOC IPs. This can involve:

- Real-Time Monitoring: Set up alerts for any real-time activity involving the IOC IPs.
- Historical Analysis: Review historical logs to identify any past connections to these IPs.

4. Endpoint Detection

Use Endpoint Detection and Response (EDR) tools to investigate endpoints for any activity related to the IOC IPs. Tools like CrowdStrike, Carbon Black, or Microsoft Defender ATP can help identify compromised endpoints.

Steps:
- Process Analysis: Look for processes that have attempted to communicate with the IOC IPs.
- File Integrity Monitoring: Check for changes in files that might be linked to communications with these IPs.

5. Correlation and Contextual Analysis

Correlate findings from network and endpoint analysis with other IOCs like domain names, file hashes, and URLs. This helps in understanding the broader context of the threat and its potential impact.

Example:
If a network connection to 192.168.1.100 is detected, check for related domains or file hashes in the same timeframe.

6. Incident Response

If malicious activity is confirmed, initiate an incident response plan. This includes:

- Isolation: Quarantine affected systems to prevent further spread.
- Eradication: Remove the malicious presence from the network.
- Recovery: Restore systems to their normal state and validate their integrity.

Example Actions:
- Block the IOC IPs at the firewall level.
- Conduct a full malware scan on affected systems.

7. Post-Incident Review

Conduct a thorough review of the incident to understand what happened and how it was handled. This step is crucial for continuous improvement.

Steps:
- Root Cause Analysis: Determine how the breach occurred and evaluate the response.
- IOC Updates: Update your IOC database with new findings to enhance future threat hunting efforts.

Scenario

Suppose your organization receives a threat intelligence report indicating that IP 203.0.113.50 is a command and control server for a known malware campaign. How will you handle it? Answer in comment section.

Threat hunting using IOC IPs is a powerful technique in proactive cybersecurity. By collecting, integrating, and analysing known malicious IPs, security teams can detect and mitigate threats before they cause significant harm.