Exfiltration Simulation/Testing

[M.Crow]

I was wondering if anyone has good procedures or methodology for simulating various kinds of data exfiltrations. We have a handful of rules related to exfiltration but have not established a meaningful way of assuring they are functional and sufficient.

Thanks!

[susekar · Accepted solution]

Hello @M.Crow ,

Greetings for the day.

To simulate data exfiltration and validate Cortex XDR rules, you can utilize built-in modules, manual transfer procedures, or third-party adversary emulation frameworks. The methodology varies depending on whether you are testing real-time prevention (BIOC/BTP) or anomaly-based detection (Analytics Engine).

1. Breach and Attack Simulation (BAS) Module

Cortex XDR includes a Breach and Attack Simulation (BAS) module (introduced in agent version 8.9.0) designed specifically for this purpose.

• Methodology: It proactively and automatically simulates real-world attacks, including data exfiltration attempts, mimicking TTPs aligned with the MITRE ATT&CK framework.

• Control: Simulations are non-destructive and can be controlled via explicit settings in the management console. By default, BAS tools are treated as malware unless the feature is enabled for testing.

2. Manual Simulation Procedures

For manual testing, procedures typically focus on simulating large outbound data transfers to trigger Analytics alerts.

Large File Uploads (Network):

• Procedures: Use protocols such as FTP, SFTP, or HTTP/HTTPS to transfer data to an external server.

• Recommended Volume: Transfers exceeding 1 GB are generally recommended to trigger "Large Upload" detections.

• Web-based Simulation: Perform a browser-based upload of a large file to a public file drop zone or external destination.

USB Data Exfiltration:

• Procedure: A process should perform massive file creation, renaming, and write activity to a USB storage device.

• Requirement: This requires the Cortex XDR Agent with the eXtended Threat Hunting (XTH) module enabled.

3. Critical Methodological Requirements

To ensure simulations are functional and sufficient, you must account for the Analytics Engine's logic:

• External vs. Local Subnet: Simulations using a command-and-control (C2) or destination server on a local subnet (for example, 192.168.x.x) often fail to trigger alerts. XDR rules for exfiltration and C2 are primarily designed to flag external connections.

• Baselining Period: Analytics-based detections (such as "Large Upload") require a training period, typically around 30 days, to establish a baseline of normal activity for the host or user before abnormal deviations can be identified.

• Detection Delay: Unlike Behavioral Threat Protection (BTP), which can be real-time, Analytics alerts are inherently delayed due to the processing time required for cloud-based anomaly calculation.

4. Adversary Emulation Frameworks

Many organizations use community-developed tools to validate MITRE ATT&CK techniques:

• Common Tools: Atomic Red Team, Caldera, and ATTPWN are frequently used to simulate adversary behaviors such as reverse shells, persistence, and data staging.

• Scripting Scenarios: Python scripts can be used to compress folders (for example, Downloads) into ZIP files and attempt to exfiltrate them via socket connections.

5. Other Exfiltration Vectors to Test

• Alternative Protocols: Large data transfers over non-standard protocols, such as UDP port 500 or DNS tunneling.

• Physical Mediums: Printing an unusually high number of files can also trigger exfiltration-related alerts if XTH is active.

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Happy New year!!

Thanks & Regards,
S. Subashkar Sekar

[M.Crow]

This is terrific, thanks Susekar!

[susekar]

You are welcome! @M.Crow