analyzing-windows-shellbag-artifacts

name	analyzing-windows-shellbag-artifacts
description	Analyze Windows Shellbag registry artifacts to reconstruct folder browsing activity, detect access to removable media and network shares, and establish user interaction with directories even after deletion using SBECmd and ShellBags Explorer.
domain	cybersecurity
subdomain	digital-forensics
tags	["shellbags","windows-registry","sbecmd","shellbags-explorer","folder-access","user-activity","removable-media","network-shares","bagmru","dfir"]
version	1.0
author	mahipal
license	Apache-2.0
nist_csf	["RS.AN-01","RS.AN-03","DE.AE-02","RS.MA-01"]

Analyzing Windows Shellbag Artifacts

Overview

Shellbags are Windows registry artifacts that track how users interact with folders through Windows Explorer, storing view settings such as icon size, window position, sort order, and view mode. From a forensic perspective, Shellbags provide definitive evidence of folder access -- even folders that no longer exist on the system. When a user browses to a folder via Windows Explorer, the Open/Save dialog, or the Control Panel, a Shellbag entry is created or updated in the user's registry hive. These entries persist after folder deletion, drive disconnection, and even across user profile resets, making them invaluable for proving that a user navigated to specific directories on local drives, USB devices, network shares, or zip archives.

When to Use

• When investigating security incidents that require analyzing windows shellbag artifacts
• When building detection rules or threat hunting queries for this domain
• When SOC analysts need structured procedures for this analysis type
• When validating security monitoring coverage for related attack techniques

Prerequisites

• Familiarity with digital forensics concepts and tools
• Access to a test or lab environment for safe execution
• Python 3.8+ with required dependencies installed
• Appropriate authorization for any testing activities

Registry Locations

Windows 7/8/10/11

Hive	Key Path	Stores
NTUSER.DAT	Software\Microsoft\Windows\Shell\BagMRU	Folder hierarchy tree
NTUSER.DAT	Software\Microsoft\Windows\Shell\Bags	View settings per folder
UsrClass.dat	Local Settings\Software\Microsoft\Windows\Shell\BagMRU	Desktop/Explorer shell
UsrClass.dat	Local Settings\Software\Microsoft\Windows\Shell\Bags	Additional view settings

BagMRU Structure

The BagMRU key contains a hierarchical tree of numbered subkeys representing the directory structure. Each subkey value contains a Shell Item (SHITEMID) binary blob encoding the folder identity:

• Root (BagMRU): Desktop namespace root
• BagMRU\0: Typically "My Computer"
• BagMRU\0\0: First drive (e.g., C:)
• BagMRU\0\0\0: First subfolder on C:

Each Shell Item contains: