Hi everyone, I'm fairly new to the security operations side of things, coming from an accounting and compliance background. I've been tasked with helping our team improve our monitoring for suspicious file activity, and after some research, setting up a canary file alert with Carbon Black seems like a logical, methodical first step for basic internal threat detection.
I've spent the last week reading documentation and old forum posts, but I'd like to propose a step-by-step process I've drafted to ensure I haven't overlooked any critical details. My goal is to create a trap that alerts us if a specific, seemingly sensitive file is accessed or modified, which could indicate insider threats or lateral movement.
Could the community please review my planned approach for gaps or best practices?
**My Planned Procedure:**
1. **Canary File Creation & Placement:**
* Create a decoy file with a enticing name (e.g., `passwords_backup_2023.xlsx`) containing fake but realistic data.
* Determine several key directories across our network—a few on file servers with broad access, one on a finance-department SharePoint, and perhaps a local directory on a high-risk user's machine as a test.
* Set restrictive but plausible permissions on the file to make it look accidentally accessible.
2. **Carbon Black Watchlist Configuration:**
* I understand I need to create a new Watchlist in the Carbon Black console focused on file access events.
* My plan is to use a hash-based rule (MD5 and SHA256) for the canary file as the primary detection method, as I've read this is more reliable than just a filename.
* Should the watchlist rule also include the file path, or is that too specific and might be missed if the file is moved?
3. **Alert Tuning & Integration:**
* Configure the alert severity and ensure it integrates with our ticketing system (ServiceNow).
* I'm considering setting a lower severity initially to monitor the alert volume—will this approach cause alert fatigue if placed incorrectly?
* Document the entire setup, including the file hashes, locations, and the rationale, for our runbook and for compliance audit trails.
My main concerns are around the operational aspects. From a compliance perspective, I need to ensure this monitoring is documented and authorized. From a practical standpoint, I want to avoid false positives from legitimate admin tools or backup processes.
Are there specific event types or process names I should exclude in the Watchlist logic? Also, any advice on the frequency of updating the canary file's hash or location to maintain effectiveness would be greatly appreciated.
Welcome! This is a fantastic first project to cut your teeth on. Coming from compliance, you're thinking about this the right way - starting with a clear, methodical process.
I'd gently suggest holding off on placing a canary on a high-risk user's local machine, at least initially. It can create unnecessary noise from legitimate activity and might be seen as targeting an individual, which can be a tricky HR conversation. Focus on the shared network locations and SharePoint first; that's where you'll likely catch the broad, suspicious lateral movement you mentioned.
For the file itself, remember to set restrictive permissions on it, making it readable but not writable by most users. The alert triggers when someone *tries* to modify it, not just read it, which is a stronger signal. Also, be sure to document exactly where you've placed these files and the alert logic. In six months, you won't want to be the "secret keeper" of your own security controls.
What's your plan for the alert response workflow? Knowing who gets the alert and what they're supposed to do with it is just as important as setting it up.