Mastering Log Investigation, PCAP Analysis, and Threat Hunting with Brim
Mastering Log Investigation, PCAP Analysis, and Threat Hunting with Brim
As organizations face increasingly sophisticated cyberattacks, the need for effective log investigation, packet capture (PCAP) analysis, and proactive threat hunting has never been greater. To tackle these challenges, security analysts need the right tools to sift through vast amounts of data quickly and accurately. Brim, an open-source platform designed for large-scale log and packet capture analysis, is emerging as a game-changer in this space. With Brim, analysts can easily investigate logs, analyze network traffic, and conduct threat hunting to identify potential security incidents.
In this blog post, we’ll explore how Brim facilitates log investigation, PCAP analysis, and threat hunting, with a focus on how you can leverage it in real-world scenarios.
What is Brim?
Brim is an open-source platform optimized for working with network security data. It is built around Zeek (formerly known as Bro), a network monitoring tool that generates high-level logs of network activity. Brim allows you to load, query, and analyze Zeek logs and PCAP (Packet Capture) files, enabling more effective network security investigations. Its core features include powerful search and filtering capabilities, full-text search, real-time packet analysis, and customizable visualizations, all aimed at making security investigations faster and more efficient.
Why Brim for Log Investigation?
When investigating security incidents, logs provide the crucial context needed to understand what happened, why it happened, and when. Logs generated by systems, servers, and applications are essential for reconstructing the events leading up to an attack. Brim simplifies the log investigation process, making it easier to process large datasets and extract valuable insights.
1. Native Integration with Zeek Logs
Zeek is a leading network monitoring tool widely used in cybersecurity, and its logs provide detailed information about network activity, such as HTTP requests, DNS queries, and connections. Brim supports Zeek’s log formats out of the box, meaning you can load these logs directly without needing to preprocess them. This saves time and effort, allowing you to start investigating immediately.
2. Advanced Querying with ZQL
Brim uses ZQL (Zeek Query Language), a powerful query language designed to handle large volumes of log data generated by Zeek. ZQL is built to allow analysts to write efficient, granular queries. For example, you can search for all DNS queries made by a particular IP address or look for HTTP requests containing a specific user-agent string. This capability makes it easy to dive into specific aspects of your network activity and spot unusual patterns that might indicate a security incident.
3. Filtering and Full-Text Search
Brim supports full-text search across logs, enabling you to search for specific events, patterns, or error messages. You can filter logs based on various fields like source IP, destination port, or timestamp. This level of flexibility is crucial for narrowing down results during investigations. For example, if you’re trying to track down unusual login attempts, you can filter for specific error messages or unusual source IPs in authentication logs.
4. Data Visualization
Brim offers intuitive data visualization tools that let you view the results of your queries in graphical formats like line charts, bar graphs, and network graphs. Visualizing the data helps identify trends, spikes, or patterns that might indicate malicious activity. For example, you can visualize HTTP requests over time and spot sudden surges in traffic that could indicate a DDoS attack or a large-scale data exfiltration.
PCAP Analysis with Brim
PCAP analysis allows you to examine network traffic at a packet level, providing visibility into the raw data transmitted across your network. By analyzing PCAP files, you can uncover details that aren’t available in logs, such as packet contents, protocol information, and timing details. Brim simplifies PCAP analysis and makes it accessible even to analysts who may not be familiar with complex network protocols.
1. Effortless Import and Parsing of PCAP Files
Brim enables you to import PCAP files directly into its interface. Once loaded, Brim automatically parses the packets and extracts critical information, such as IP addresses, protocols, payloads, and ports. This automated parsing reduces the manual effort typically required to analyze raw PCAP data.
For example, if you’re investigating a suspicious IP address, you can load the PCAP data and search for all packets originating from that IP. Brim will show you all associated network activity, making it easier to trace back an attacker’s movement through the network.
2. Real-Time Traffic Exploration
Brim’s real-time traffic analysis capability is particularly useful for analyzing live network traffic during an ongoing incident. As new packets arrive, you can immediately filter, examine, and identify suspicious patterns. For instance, you could spot high-volume traffic, connections to known bad IPs, or traffic on unusual ports—indicators of potential malware or C2 (Command and Control) activity.
3. Advanced Packet Filtering and Search
Brim supports advanced filtering of packets based on parameters like source/destination IP, port number, protocol (e.g., TCP, UDP, ICMP), or packet size. This granular filtering allows you to zoom in on specific activities. For example, you could filter for DNS requests to suspicious domains or search for all packets containing unusual payloads.
Let’s say you’re hunting for an unusual connection on port 443 (typically used for HTTPS). With Brim, you could filter for all packets on port 443 and drill down further to investigate the traffic associated with that port.
4. Correlation with Zeek Logs
One of Brim’s most powerful features is its ability to correlate packet data with Zeek logs. If you’ve imported both Zeek logs and a PCAP file, you can view them side by side. This makes it easy to connect network activity with specific log events. For instance, if you see an unusual outbound connection in a PCAP file, you can cross-reference it with Zeek’s HTTP or DNS logs to find related activities, such as suspicious domain lookups or abnormal HTTP requests.
Threat Hunting with Brim
Threat hunting is a proactive process where security analysts search for hidden threats within their network before they cause harm. Brim makes threat hunting more efficient by offering advanced querying, filtering, and analysis tools that allow you to pinpoint suspicious activity and identify indicators of compromise (IoCs).
1. Building Custom Detection Queries
With Brim, you can craft custom queries tailored to your network’s unique environment and the types of attacks you’re trying to detect. For example, you might create a query to detect C2 communication attempts or lateral movement within your network. This ability to build custom detection queries allows you to tailor your threat-hunting efforts to the specific needs of your network, improving your chances of detecting emerging threats.
2. Historical Data Search
Threat hunting often involves analyzing historical data to uncover threats that have evaded detection. Brim enables you to quickly search through large volumes of log and PCAP data, pinpointing patterns of attack or anomalies that may have gone unnoticed. You can search for network activity patterns over time, such as a gradual increase in DNS requests to a suspicious domain or recurring traffic to an unusual port.
3. Anomaly Detection
Using Brim’s powerful filtering and visualization features, you can easily spot anomalous behavior on your network. For instance, you might notice a sudden spike in network traffic, which could signal the beginning of a DDoS attack or a large-scale data exfiltration attempt. Brim’s graphical tools help you quickly identify these anomalies and investigate them further.
4. Collaboration and Knowledge Sharing
Effective threat hunting often involves teamwork, and Brim enables collaboration by allowing analysts to share queries, findings, and insights with colleagues. This fosters a collective knowledge-sharing environment that helps uncover threats faster. Analysts can share custom detection queries or export visualizations to demonstrate findings and coordinate a more comprehensive response.
Conclusion
Brim is a powerful and intuitive platform that simplifies the complex tasks of log investigation, PCAP analysis, and threat hunting. With its robust query language, full-text search, real-time packet analysis, and data visualization tools, Brim provides security analysts with everything they need to efficiently uncover threats and investigate security incidents. Whether you are a beginner or an experienced analyst, Brim can help you perform detailed investigations and proactively hunt for potential security risks.
By mastering Brim, you’ll be better equipped to handle modern cyber threats, with the tools and techniques to effectively search, analyze, and visualize network traffic and logs. Brim is a must-have tool for any security operations team looking to stay ahead of evolving threats and protect their network infrastructure.
By enhancing your technical understanding of how Brim works and applying it to real-world scenarios, you’ll be better prepared to perform detailed investigations and contribute to more proactive threat hunting efforts.