Proactive Threat Hunting Based on Emerging TTPs

Use Case: Proactive Threat Hunting Based on Emerging TTPs Role: Threat Hunter / Security Operations Center (SOC) Analyst Scenario: Investigating Potential Threat Activity Based on New Tactics, Techniques, and Procedures (TTPs)

Situation: The threat intelligence team has reported a new set of Tactics, Techniques, and Procedures (TTPs) used by a sophisticated threat actor. The TTPs describe specific behaviors and methods of attack, such as how the threat actor establishes persistence, performs privilege escalation, or communicates with command-and-control (C2) servers. Although there are no specific Indicators of Compromise (IOCs) like file hashes or IP addresses associated with these behaviors, the SOC team wants to proactively hunt for any signs of the new TTPs within their environment.

Traditional security tools typically rely on known IOCs and signatures, which may not detect new or evolving TTPs. The SOC team needs a solution that can identify suspicious behaviors and uncover any potential indicators of these techniques, even if they don’t match known patterns.

Challenge: Detecting new TTPs requires analyzing behavioral patterns, examining historical and current file activities, and uncovering relationships between seemingly benign files and processes. This can be extremely time-consuming if done manually, and conventional security solutions may lack the depth or context needed to identify subtle indicators of advanced threats. The SOC analyst needs a way to conduct a proactive threat hunt based on TTPs and identify any suspicious behavior that might indicate the presence of a sophisticated attacker in the network.

Solution: Using Stairwell to Proactively Hunt for Threats Based on TTPs

1. Mapping TTPs to Search Criteria: The SOC analyst starts by breaking down the newly reported TTPs into specific search criteria, such as:
   • File behaviors (e.g., execution of uncommon utilities, DLL side-loading, or process injection).
   • Network activity (e.g., unusual outbound connections, beaconing patterns, or data exfiltration).
   • Persistence mechanisms (e.g., scheduled tasks, registry keys, or unusual services). Each TTP is translated into a set of characteristics or conditions that can be used for querying the environment.
2. Creating and Running YARA Rules for TTP Detection:
   • The analyst writes custom YARA rules to detect these behaviors. For example, if a TTP indicates the use of a specific API for process injection, a YARA rule can be created to identify any file using this API.
   • The YARA rules are uploaded to Stairwell and automatically executed across the organization’s file inventory and historical data to identify any matches.
3. Leveraging Stairwell’s Behavioral Analysis: Stairwell’s platform performs behavioral analysis across all files and processes seen within the environment. The analyst configures the system to search for behaviors related to the reported TTPs, such as:
   • Detecting if any executables have spawned child processes or loaded modules in a manner consistent with the reported TTPs.
   • Identifying files that attempt to access sensitive system resources or modify security configurations.
4. Running Recursive Variant Discovery (RTG) to Detect Related Files:
   • The analyst uses Run to Ground (RTG) to analyze any suspicious files or processes that match the TTP search criteria.
   • RTG discovers related file variants and maps the relationships between different files and processes, even if they are not exact matches to known malware samples. This helps uncover potential connections between low-prevalence files that could be part of an attack chain.
5. Investigating File Inventory for Low-Prevalence and Anomalous Files:
   • The analyst reviews Stairwell’s file inventory to identify low-prevalence files that may have behaviors or attributes linked to the new TTPs.
   • This includes identifying newly introduced executables or scripts, files with unusual or unknown metadata, and executables that have been observed using known TTP-related techniques (e.g., masquerading as system files).
6. Correlating with Historical Data for Lateral Movement and Persistence:
   • Stairwell’s historical data analysis allows the analyst to trace any lateral movement or persistence attempts made by suspicious files.
   • The analyst looks for signs of lateral movement, such as processes spawning on multiple endpoints, or persistence mechanisms like creating scheduled tasks or modifying registry keys.
7. Reviewing Network Activity for Anomalous Behavior:
   • The analyst cross-references the results from the file and behavioral analysis with network activity logs to identify unusual patterns.
   • If the TTPs suggest C2 communication or data exfiltration, the analyst checks for unusual outbound connections, communication to low-prevalence domains, or long-lived network sessions that may have gone unnoticed.
8. Documenting Findings and Escalating for Response:

If the analysis reveals any suspicious files or behaviors consistent with the new TTPs, the analyst generates a detailed report, including:

• The specific TTPs that were matched.
• Affected machines, users, and timestamps.
• Relationships and behaviors observed. The report is escalated to the incident response team for further investigation and, if necessary, immediate containment and remediation.

9. Continuous Monitoring and Automation of TTP-Based Threat Hunts: After completing the initial threat hunt, the analyst configures Stairwell to continuously monitor for these TTPs, ensuring that any future behaviors related to these techniques are detected and alerted upon immediately. Automated alerts are set up to notify the SOC team if any new files or behaviors associated with the TTPs appear in the environment, providing proactive defense against emerging threats.
10. Review and Refinement of Detection Rules: The analyst periodically reviews the effectiveness of the YARA rules and search criteria, refining them as new intelligence becomes available. This iterative approach ensures that the organization remains agile in detecting and responding to evolving threats that may employ the same or similar TTPs in the future.

Impact: Stairwell’s advanced behavioral analysis, recursive variant discovery, and automated YARA rule execution enable the SOC analyst to quickly and effectively hunt for new TTPs within the environment. By leveraging detailed threat intelligence and proactive search techniques, the analyst is able to uncover potential indicators of sophisticated threat activity before it escalates to a full-blown incident. This proactive approach significantly reduces the risk of undetected compromise and strengthens the organization’s overall security posture against evolving threats.