How Malicious npm Packages Can Leak Data via Ngrok Tunnels

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Introduction

The recent discovery of a legitimate npm package exfiltrating sensitive payment data via an ngrok tunnel highlights the growing risks in the software supply chain. Attackers are increasingly abusing trusted platforms to distribute malware, making detection and mitigation critical for cybersecurity teams.

Learning Objectives

  • Understand how npm packages can be weaponized for data exfiltration
  • Learn to detect and block malicious ngrok tunneling activity
  • Apply mitigation techniques to secure your software supply chain

1. Detecting Malicious npm Packages

Command:

npm audit --production

Step-by-Step Guide:

  1. Run the command in your project directory to scan for known vulnerabilities.
  2. Review the output for high-risk packages marked as malicious.
  3. Use `npm uninstall ` to remove suspicious dependencies.

Why It Matters:

This command helps identify compromised packages before they execute harmful actions like data exfiltration.

2. Identifying ngrok Tunnels in Network Traffic

Command (Linux):

sudo netstat -tulnp | grep -i ngrok

Step-by-Step Guide:

  1. Execute the command to check for active ngrok connections.
  2. If ngrok is detected without authorization, terminate the process: 
    kill -9 $(pidof ngrok)

3. Block ngrok domains at the firewall level.

Why It Matters:

Ngrok tunnels can bypass traditional security controls, making detection crucial.

3. Blocking Unauthorized Data Exfiltration

Command (Windows Firewall):

New-NetFirewallRule -DisplayName "Block Ngrok" -Direction Outbound -Program "ngrok.exe" -Action Block

Step-by-Step Guide:

1. Open PowerShell as Administrator.

  1. Run the command to block ngrok’s outbound traffic.

3. Verify the rule is active with:

Get-NetFirewallRule -DisplayName "Block Ngrok"

Why It Matters:

Preventing unauthorized outbound connections stops data leaks before they occur.

4. Analyzing Suspicious npm Package Behavior

Command (Linux Process Monitoring):

strace -f -p $(pgrep -f "node.malicious-package") -o /tmp/npm_trace.log

Step-by-Step Guide:

1. Identify the suspicious Node.js process ID.

  1. Use `strace` to log system calls and network activity.

3. Check `/tmp/npm_trace.log` for unauthorized data transfers.

Why It Matters:

Real-time monitoring helps detect malicious behavior before data is exfiltrated.

5. Securing CI/CD Pipelines Against Malicious Packages

Command (GitHub Actions Workflow Check):

- name: Scan for Malicious Dependencies 
run: npm audit --audit-level=critical

Step-by-Step Guide:

  1. Add this step to your GitHub Actions workflow.
  2. Fail the build if critical vulnerabilities are found.

3. Enforce mandatory security scans before deployment.

Why It Matters:

Automated checks prevent compromised packages from entering production.

What Undercode Say

  • Key Takeaway 1: Attackers increasingly abuse trusted platforms (like npm) to distribute malware.
  • Key Takeaway 2: Ngrok tunnels are a common exfiltration method due to their ability to bypass firewalls.

Analysis:

The incident underscores the need for continuous monitoring of third-party dependencies. Organizations must implement runtime protection, network traffic analysis, and strict CI/CD security policies to mitigate supply chain attacks.

Prediction

As attackers refine their techniques, we’ll see more legitimate packages compromised for data theft. Companies must adopt zero-trust principles and behavioral analysis tools to detect anomalies before breaches occur.

IT/Security Reporter URL:

Reported By: Safetycli Payment – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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