REPORT – USB Passthrough Instability in VirtualBox (Kali Linux) – v1.0.0

0.0 Executive Summary

This report explains how repeated USB failures caused system crashes during a Kali Linux lab running in a virtual machine. The goal was to find the cause of the connection drops and still complete the task of setting up a secure Linux filesystem. The issue was traced to unstable communication between the Windows host and VirtualBox during USB passthrough. This caused the USB device to disconnect during heavy write operations like formatting.

The system was stabilized by adjusting power settings and switching the virtual USB controller to a more reliable mode. Once stable, Linux security controls were applied using the noexec mount option and proper file ownership. This ensured the USB could store data but could not run malicious files.

1.0 USB I/O Failure & Virtualization Instability Analysis

1.1 Project Description

The goal of this task was to fix USB instability in a virtual machine and safely manage external storage using Linux.

The work focused on:

Fixing Connection Issues: Identify why the USB device disconnects during use
Setting Up Filesystems: Create and format partitions using Linux tools
Improving Security: Prevent files on the USB from being executed
Managing Access: Assign correct ownership so normal users can safely use the device

This ensures the USB device is both usable and secure inside a virtual environment.

1.2 Technical Task / Troubleshooting Process

The process focused on finding where the failure was happening and fixing it step by step.

Key Actions & Observations

1. Hardware Stabilization

USB disconnections happened during heavy write operations (like formatting)
The issue was linked to host power settings and USB controller behavior
Switching VirtualBox to USB 2.0 (EHCI) improved stability

2. Filesystem Setup

Used diskpart to clean the drive on Windows
Used fdisk and mkfs.ext4 in Linux to create and format partitions
Fixed “device busy” issues by unmounting active volumes

3. Security Configuration

Mounted the USB with noexec to block file execution
Tested by running a script (test.sh) which failed with “Permission Denied”
Changed ownership using chown so the standard user could manage files safely

4. Root Cause

The failure was caused by unstable USB passthrough between the host system and VirtualBox.
This instability appeared during high disk activity and caused the device to disconnect.

1.3 Resolution and Validation

The system was stabilized and secured using the following setup:

Parameter	Configuration Value
Hypervisor Setting	USB 2.0 (EHCI)
Filesystem Type	EXT4
Security Flag	noexec
Owner	kali:kali

Validation Steps

Stable Connection
- USB remained connected during full formatting operations
Correct Permissions
- Verified ownership using ls -l
Security Enforcement
- Script execution failed even with execute permissions
- Confirms noexec is working at the kernel level

2.0: CONCLUSION

2.1 Key Takeaways

USB stability directly affects virtual machine performance
Host system settings can break virtualization even if the guest OS is correct
Linux mount options provide strong security controls
Testing should include attempts to break the system (negative testing)

2.2 Security Implications & Recommendations

Risks

1. Malware Execution from USB

USB devices can carry malicious scripts

Fix

Use noexec on all removable drives

2. Improper Permissions

Using root ownership increases risk of mistakes