CEF – Common Event Format

Common Event Format. It is an open standard format for logging security events that is designed to help organizations aggregate and analyze event data from multiple security systems. CEF is commonly used by security information and event management (SIEM) systems to collect, store, and correlate data from different sources in a standardized way.

Key Features of CEF:

1. Standardized Log Format:
   • CEF provides a standardized format for representing security events, allowing for consistent log data from different security tools (e.g., firewalls, intrusion detection/prevention systems, antivirus software).
2. Fields in CEF:
   • The format defines specific fields such as:
     • Device Vendor: The vendor of the security device or software generating the log (e.g., Cisco, Symantec).
     • Device Product: The product name of the security device or software.
     • Event Class ID: A unique identifier for the event type.
     • Name: A description or name of the event.
     • Severity: The severity level of the event (e.g., high, medium, low).
     • Extension: Additional custom data related to the event.
3. Flexibility:
   • The format is flexible and extensible, allowing for customization of event logs to suit different environments and tools. It enables better integration of data from various sources.
4. Ease of Parsing:
   • CEF logs are typically plain-text and can be easily parsed by both humans and automated systems. This makes it simpler for security analysts and SIEM tools to process the data and respond to potential threats.
5. Interoperability:
   • CEF is widely supported by various vendors and security products, making it easier for organizations to integrate different security solutions and gain a comprehensive view of their security posture.

Example of a CEF Log Entry:

Here is an example of a CEF log entry:

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CEF:0|Cisco|ASA|9.1|106001|Connection established|5|src=192.168.1.10 dst=10.10.10.10 spt=12345 dpt=80 proto=TCP msg=Connection established successfully

In this example:

• Cisco is the vendor.
• ASA is the product (Cisco Adaptive Security Appliance).
• 106001 is the event class ID.
• Connection established is the name of the event.
• src, dst, spt, dpt, proto, and msg are the event details.

Benefits of Using CEF:

1. Centralized Event Logging:
   • CEF allows security teams to centralize logs from multiple security devices, simplifying monitoring and analysis.
2. Faster Threat Detection:
   • The standardized format makes it easier for SIEMs to process logs quickly, aiding in faster identification of security incidents.
3. Compliance:
   • CEF can help organizations meet regulatory compliance requirements by ensuring consistent and structured logging of security events.
4. Enhanced Data Correlation:
   • The standardized nature of CEF makes it easier to correlate logs from different sources, helping organizations detect complex threats across their environment.

Conclusion:

CEF is a powerful and flexible log format that plays a crucial role in modern cybersecurity environments, particularly when used with SIEM systems for event management, monitoring, and threat detection. By standardizing log data, it facilitates better integration, analysis, and response to security incidents.