Overview of File Integrity Monitoring

File Integrity Monitor (FIM)

Threat Stack offers File Integrity Monitoring (FIM) as part of the Host Intrusion Detection feature. This enables a continuous security monitoring solution and helps you achieve:

• Integrated near real-time monitoring of any changes to critical files or directories on all business critical systems with a very low footprint.
• Notifications and alerts for any file modifications events and access events (such as opened, copy, move, create, viewed and modified).
• Rich, context-based audit trail with system state context for reducing false positives while maintaining complex compliance requirements.
• Alerting rules for differentiated alerting and notification mechanisms based on the severity of the event, asset value and the context of the event.

Base Rule Set Review

Threat Stack provides a library of predefined file monitoring rules within the Base Rule Set for the most common use cases. The Base Rule Set includes:

• Files: Configuration File Changes - This rule monitors changes to your system’s configuration files, specifically the /etc/ directory.
• Files: System File Changes - This rule monitors changes to your system-specific files. By default, it monitors changes in the following directories:
  • /usr/sbin/
  • /bin/
  • /sbin/
  • /lib/
• Files: Secret File Opens - This rule monitors changes to directories identified as being important. Threat Stack sets this rule to monitor the “/home/ubuntu/.aws/” directory by default. You can add any important directories to this rule to enable monitoring. To learn how to add a new directory to the “Files: Secret File Opens” rule, please see the ‘Useful Workflows and Processes’ below.

Important

The “Files: Configuration File Changes” and the “Files: System File Changes” rules monitor 'Modify' events. The "Files: Secret File Opens" rule monitors 'Open' events.

Useful Workflows and Processes

You can modify Threat Stack provided rulesets or create additional rulesets that are specific to their respective environments. The rules can monitor multiple files, directories or sometimes only monitor a critical file like an application configuration (.conf) file.

Workflows and topics that you might find useful include:

• Add a new directory to the “File: Secret File Opens” rule
• Change a tag on a ruleset
• Configure an event query, alert rules, and suppression filters
• Create a FIM rule and add a user specific suppression

These workflows are not unique to FIM. You can apply the logic and workflow on the Rules page.

Add a New Directory To Monitor

Follow these instructions to add new directories to the “Files: Secret File Opens” rule within Threat Stack.

1. In the left navigation pane, click the Rules tab.

   
   

2. Select the Base Rule Set.

   
   

3. Click the Show More link to display additional rules.

   
   

4. Select the Files: Secret File Opens rule from the list.

   
   

5. Click the File Paths link.

   
   

6. In the right view pane, the File Paths to Monitor screen is displayed.

   
   

7. Click the Add Another Path button.
8. Enter a new path name in the Enter a path field.

   
   

   Note

   You can enable recursive monitoring for a specific file path by selecting the Recursive? check box. It will allow Threat Stack to monitor changes in that directory and all of its subdirectories.

9. Save the new path by clicking the Update Rule Paths button.

   
   

10. The file paths count shown in parenthesis will be updated to reflect your changes.