In the ever-evolving landscape of cybersecurity, adapting to new technologies is crucial for staying ahead of potential threats. At STL Digital, we recently undertook a significant project to transition the SIEM tool for a major customer from ArcSight to Microsoft Sentinel. As the SOC Lead overseeing this transformation, I am excited to share our journey, challenges, and the benefits we’ve realized with this shift.
The Need for Change
Our customer, India’s largest independent oil and gas exploration and production company, relied heavily on ArcSight for their Security Information and Event Management (SIEM) needs. While ArcSight served its purpose well, the rapid advancements in cyber threats and the increasing complexity of IT environments necessitated a more advanced and scalable solution. Microsoft Sentinel emerged as the ideal choice due to its robust capabilities, seamless integration with existing Microsoft environments, and advanced AI-driven threat detection features.
Transition Processes
Transitioning from one SIEM to another is a complex endeavour that requires meticulous planning and execution. Our approach was structured around several key phases:
- Assessment and Due Diligence
We began with a thorough assessment of the existing ArcSight environment, identifying the critical security events, log sources, and workflows that needed to be migrated. This phase also involved stakeholder meetings to understand their specific requirements and pain points with the current setup.
- Designing the New Architecture
Using insights from the assessment phase, we designed a robust and cost-conscious Sentinel architecture. This included:
- Smartly configured Data Collection Rules (DCRs) to filter noise at the source
- Routing only security-relevant logs to Analytics Tables while directing others to Basic Logs
- Creating workspaces aligned with business units
- Defining custom KQL transformations to parse and shape logs at ingestion
- Architecting analytics rules, workbooks, and Logic App playbooks based on critical use cases
This filtration-first approach laid the groundwork for a lean, high-performance environment.
- Deployment and Integration
The deployment phase involved setting up Microsoft Sentinel in the customer’s environment, ensuring seamless integration with existing Microsoft tools such as Azure Active Directory, Office 365, and Microsoft Defender. We also migrated critical log data and security events from ArcSight to Sentinel, ensuring no loss of historical data.
Additionally, logs from firewalls and core switches were routed through a log forwarder (Linux) to the Log Analytics workspace using Azure Monitor Agent (AMA) and Data Collection Rules (DCR). We implemented specific configurations on the log forwarder to store these logs on a separate dedicated drive, enabling efficient log management. Furthermore, logs were pre-sorted on the forwarder based on hostname, improving organization and streamlining downstream processing.
- Testing and Fine-Tuning
Thorough testing was conducted to validate the new setup. This included running simulated attacks to test the detection and response capabilities of Microsoft Sentinel. Based on the results, we fine-tuned the analytics rules and playbooks to ensure optimal performance.
- Training and Handover
To ensure a smooth transition, we provided comprehensive training sessions for the customer’s SOC team, covering the functionalities of Microsoft Sentinel, best practices for threat detection and response, and hands-on exercises. The final handover included detailed documentation and ongoing support to address any post-deployment issues.
Benefits Realized
The transition to Microsoft Sentinel brought about several significant benefits for our customer:
- Enhanced Threat Detection: By leveraging Microsoft Sentinel’s AI-driven analytics in combination with Microsoft Defender XDR, we achieved faster and more accurate threat detection. This integration significantly reduced response times and improved our ability to contain and mitigate risks effectively.
- Scalability and Flexibility: Being a cloud-native SIEM, Microsoft Sentinel offered unparalleled scalability, allowing the customer to handle increasing log data volumes without performance degradation.
- Cost Efficiency: With Sentinel’s pay-as-you-go pricing model, the customer experienced cost savings, only paying for the resources used and avoiding the overhead costs associated with maintaining on-premises infrastructure.
- Improved Collaboration: The seamless integration with Microsoft Teams and other collaboration tools facilitated better communication and coordination among the SOC team members, enhancing overall efficiency.
Conclusion
The successful transition from ArcSight to Microsoft Sentinel marks a significant milestone in our continuous efforts to provide cutting-edge Cyber Security solutions for our customers. This journey highlights the importance of meticulous planning, stakeholder collaboration, and leveraging advanced technologies to enhance security postures.
At STL Digital, we are committed to helping organizations navigate the complexities of cybersecurity and achieve their goals. If you’re considering a similar transition or looking to enhance your security operations, feel free to reach out to us for a consultation. Together, we can build a resilient and secure future.
