Threat hunting: the proactive search for cyber threats lurking undetected within an organization’s network. Unlike reactive security measures that respond to known threats, threat hunting takes an offensive approach, assuming breaches have already occurred and actively seeking out malicious activity that has bypassed traditional security controls. By embracing this proactive stance, organizations can significantly reduce the dwell time of attackers and minimize the potential damage caused by advanced persistent threats (APTs) and other sophisticated attacks.
What is Threat Hunting?
Defining Threat Hunting
Threat hunting is a security discipline that involves proactively and iteratively searching through networks, endpoints, and datasets to uncover hidden malicious activities. It’s a human-led process, enhanced by technology, that goes beyond automated alerts and signature-based detections. Think of it as digital detective work, where security analysts leverage their expertise and intuition to identify anomalies and uncover indicators of compromise (IOCs).
- Proactive: Actively seeking out threats, rather than waiting for alerts.
- Iterative: The process involves continuous refinement of hypotheses and investigation techniques.
- Human-led: Relies on the expertise and intuition of security analysts.
- Technology-enabled: Leverages security information and event management (SIEM) systems, endpoint detection and response (EDR) solutions, and other tools.
Threat Hunting vs. Incident Response
While both threat hunting and incident response are crucial security functions, they differ significantly in their objectives and approach.
- Threat Hunting:
Goal: To proactively discover hidden threats that have bypassed existing security controls.
Trigger: Driven by hypotheses, intelligence, or observed anomalies.
Scope: Broad, encompassing the entire network and endpoint environment.
Outcome: Identification of previously unknown threats and improvement of security posture.
- Incident Response:
Goal: To contain, eradicate, and recover from a confirmed security incident.
Trigger: A security alert or confirmed breach.
Scope: Focused on the specific incident and affected systems.
Outcome: Resolution of the incident and restoration of normal operations.
Essentially, threat hunting seeks to prevent incidents by finding and eliminating threats before they can cause damage, while incident response reacts to incidents that have already occurred. Threat hunting can often trigger an incident response process when a threat is discovered.
The Importance of Threat Hunting
In today’s evolving threat landscape, traditional security measures are often insufficient to protect against advanced attacks. Threat hunting offers several key benefits:
- Reduced Dwell Time: Finding and eliminating threats earlier in the attack lifecycle. Research indicates that the average dwell time for attackers is still measured in months, highlighting the need for proactive measures.
- Improved Security Posture: Strengthening defenses by identifying vulnerabilities and weaknesses in the security infrastructure.
- Enhanced Threat Intelligence: Gathering valuable insights into attacker tactics, techniques, and procedures (TTPs).
- Increased ROI on Security Investments: Maximizing the value of existing security tools by leveraging them in proactive threat hunting activities.
- Compliance: Meeting regulatory requirements for proactive security measures.
Building a Threat Hunting Program
Defining Objectives and Scope
Before embarking on threat hunting activities, it’s essential to clearly define the objectives and scope of the program. What are you trying to achieve? Which assets are most critical to protect? Answering these questions will help focus your efforts and ensure that your threat hunting activities are aligned with your organization’s overall security goals.
- Identify Critical Assets: Determine the data, systems, and applications that are most valuable and sensitive.
- Define Threat Landscape: Understand the threats that are most likely to target your organization. Consider industry-specific threats, known vulnerabilities, and emerging attack trends.
- Establish Key Performance Indicators (KPIs): Define metrics to measure the success of your threat hunting program. Examples include the number of threats identified, the reduction in dwell time, and the improvement in security posture.
- Develop a Charter: Document the purpose, scope, and responsibilities of the threat hunting team. This helps ensure that everyone is on the same page and that the program is aligned with the organization’s overall security strategy.
Assembling a Threat Hunting Team
A successful threat hunting program requires a team with a diverse skillset and expertise. The ideal team should include:
- Security Analysts: Experts in security monitoring, incident response, and threat intelligence. They should have a strong understanding of attacker TTPs and the ability to analyze security logs and data.
- Data Scientists: Professionals with expertise in data analysis, machine learning, and statistical modeling. They can help identify anomalies and patterns in large datasets.
- System Administrators: Individuals with in-depth knowledge of the organization’s IT infrastructure. They can provide valuable insights into system behavior and help identify potential vulnerabilities.
- Network Engineers: Experts in network architecture, protocols, and security. They can help identify suspicious network traffic and analyze network logs.
- Threat Intelligence Analysts: Professionals who specialize in gathering and analyzing threat intelligence from various sources. They can provide valuable context and insights into emerging threats.
Selecting the Right Tools and Technologies
Threat hunting relies on a variety of tools and technologies to collect, analyze, and visualize data. Some of the most common tools used in threat hunting include:
- Security Information and Event Management (SIEM) Systems: Centralized log management and analysis platforms that aggregate security data from various sources. Examples include Splunk, QRadar, and ArcSight.
- Endpoint Detection and Response (EDR) Solutions: Tools that monitor endpoint activity and provide real-time detection and response capabilities. Examples include CrowdStrike Falcon, Carbon Black EDR, and SentinelOne.
- Network Traffic Analysis (NTA) Tools: Solutions that capture and analyze network traffic to identify malicious activity. Examples include Vectra Cognito, Darktrace, and ExtraHop.
- Threat Intelligence Platforms (TIPs): Platforms that aggregate threat intelligence from various sources and provide context and insights into emerging threats. Examples include Recorded Future, ThreatConnect, and Anomali.
- Data Analytics Platforms: Tools that enable analysts to analyze large datasets and identify anomalies and patterns. Examples include Jupyter Notebook, Python, and R.
Developing Threat Hunting Methodologies
Threat hunting methodologies provide a structured approach to searching for threats. There are several common methodologies used in threat hunting:
- Intelligence-Driven Hunting: Based on threat intelligence feeds and reports. Hunters use intelligence to identify potential threats and develop hypotheses for investigation.
Example: Hunting for activity related to a known APT group that is targeting organizations in your industry.
- Anomaly-Based Hunting: Focused on identifying deviations from normal behavior. Hunters use baselines and statistical analysis to detect anomalies that may indicate malicious activity.
Example: Hunting for unusual network traffic patterns or suspicious user activity that deviates from established norms.
- Hypothesis-Driven Hunting: Starts with a specific hypothesis about a potential threat. Hunters then gather data and conduct investigations to test the hypothesis.
Example: Hypothesis: “A user account was compromised using credential stuffing.” The hunter would then analyze login logs and user activity to confirm or deny this hypothesis.
- Situational Awareness Hunting: Driven by events or changes in the environment. Hunters respond to new vulnerabilities, security alerts, or changes in network topology.
Example: Hunting for exploitation attempts following the release of a critical vulnerability.
The Threat Hunting Process
Planning and Preparation
Before initiating a threat hunt, it’s crucial to thoroughly plan and prepare. This involves:
- Defining the Scope: Determine the specific systems, networks, and datasets that will be included in the hunt.
- Gathering Intelligence: Collect relevant threat intelligence and information about potential threats.
- Developing Hypotheses: Formulate hypotheses about potential malicious activity based on the intelligence gathered.
- Selecting Tools and Techniques: Choose the appropriate tools and techniques for the hunt.
Data Collection and Analysis
The next step is to collect and analyze data from various sources. This may involve:
- Collecting Logs and Events: Gather security logs and events from SIEM systems, EDR solutions, and other security tools.
- Analyzing Network Traffic: Capture and analyze network traffic to identify suspicious patterns.
- Examining Endpoint Activity: Monitor endpoint activity to detect malicious behavior.
- Correlating Data: Correlate data from different sources to identify patterns and relationships.
Investigation and Validation
Once potential threats have been identified, it’s essential to investigate and validate them. This may involve:
- Analyzing Malware Samples: Analyze malware samples to understand their functionality and behavior.
- Tracing Activity Back to the Source: Track suspicious activity back to its origin to identify the attacker.
- Confirming Indicators of Compromise (IOCs): Verify that the identified IOCs are associated with malicious activity.
- Documenting Findings: Document all findings and observations in a clear and concise manner.
Response and Remediation
If a threat is confirmed, it’s crucial to take immediate action to contain, eradicate, and recover from the incident. This may involve:
- Isolating Affected Systems: Isolate infected systems from the network to prevent further spread of the malware.
- Removing Malware: Remove the malware from the infected systems.
- Patching Vulnerabilities: Patch vulnerabilities that were exploited by the attacker.
- Restoring Data: Restore data from backups if necessary.
- Updating Security Controls: Update security controls to prevent future attacks.
Learning and Improvement
The final step in the threat hunting process is to learn from the experience and improve the program. This involves:
- Reviewing the Hunt: Analyze the hunt to identify what worked well and what could be improved.
- Updating Threat Intelligence: Update threat intelligence with new information about attacker TTPs.
- Improving Security Controls: Implement new security controls to prevent future attacks.
- Training Analysts: Provide training to analysts to improve their skills and knowledge.
- Documenting Lessons Learned: Document lessons learned from the hunt to improve future hunts.
Common Threat Hunting Scenarios
Hunting for Lateral Movement
Lateral movement occurs when an attacker gains access to one system and then uses that system to move to other systems within the network. This is a common TTP used by attackers to gain access to sensitive data and critical systems. To hunt for lateral movement, analysts can:
- Monitor User Account Activity: Look for unusual login patterns, such as logins from multiple locations or at unusual times.
- Analyze Network Traffic: Look for suspicious network connections between systems, such as connections to internal systems from external sources.
- Examine Process Activity: Look for processes that are running on multiple systems or that are accessing sensitive data.
- Example: An analyst discovers that a user account has logged in from two different countries within a short period of time. This could indicate that the account has been compromised and is being used for lateral movement.
Hunting for Data Exfiltration
Data exfiltration is the unauthorized transfer of data from an organization’s network. This is a critical concern for organizations that handle sensitive data. To hunt for data exfiltration, analysts can:
- Monitor Network Traffic: Look for large outbound data transfers or connections to suspicious IP addresses.
- Analyze File Activity: Look for unusual file access patterns or the creation of large archives.
- Examine User Activity: Look for users who are accessing sensitive data and then connecting to external services.
- Example: An analyst discovers a large amount of data being transferred from a file server to an external IP address. This could indicate that an attacker is exfiltrating sensitive data.
Hunting for Phishing Attacks
Phishing attacks are a common way for attackers to gain access to an organization’s network. To hunt for phishing attacks, analysts can:
- Analyze Email Traffic: Look for suspicious emails with malicious attachments or links.
- Monitor User Activity: Look for users who are clicking on suspicious links or entering their credentials on fake websites.
- Examine DNS Logs: Look for connections to suspicious domains that are associated with phishing attacks.
- Example:* An analyst discovers an email that appears to be from a legitimate company but contains a link to a fake login page. This could indicate a phishing attack.
Conclusion
Threat hunting is an essential component of a comprehensive cybersecurity strategy. By proactively searching for hidden threats, organizations can reduce dwell time, improve security posture, and enhance their ability to defend against advanced attacks. Building a successful threat hunting program requires a dedicated team, the right tools, and a structured methodology. By embracing a proactive and iterative approach, organizations can stay one step ahead of the attackers and protect their valuable assets. The insights gained from threat hunting exercises can inform future security investments and lead to a more resilient security posture.
