What it does. Analyze Windows Shellbag (BagMRU) registry artifacts with SBECmd and Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).
Install
npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill analyzing-windows-shellbag-artifacts, or copy the skill folder into ~/.claude/skills/analyzing-windows-shellbag-artifacts/.- Raw file:
curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/analyzing-windows-shellbag-artifacts/SKILL.md
SKILL.md (verbatim)
name: analyzing-windows-shellbag-artifacts
description: Analyze Windows Shellbag (BagMRU) registry artifacts with SBECmd and
Shellbags Explorer to reconstruct folder browsing activity and prove user interaction
with directories, including removable media and network shares, even after the
folders are deleted. Use when reconstructing a user's folder access history or
proving access to a since-removed directory in DFIR work.
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-03
- DE.AE-02
- RS.MA-01
mitre_attack:
- T1083
- T1074.001
- T1135
- T1025
- T1070.004
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:
- Item type (folder, drive, network, zip, control panel)
- Short name (8.3 format)
- Long name (Unicode)
- Creation/modification timestamps
- MFT entry/sequence for NTFS folders
SBECmd (Command Line)
# Parse shellbags from a directory of registry hives
SBECmd.exe -d "C:\Evidence\Registry" --csv C:\Output --csvf shellbags.csv
# Parse from a live system (requires admin)
SBECmd.exe --live --csv C:\Output --csvf live_shellbags.csv
# Key output columns:
# AbsolutePath - Full reconstructed path
# CreatedOn - When the folder was first browsed
# ModifiedOn - When view settings were last changed
# AccessedOn - Last access timestamp
# ShellType - Type of shell item (Directory, Drive, Network, etc.)
# Value - Raw shell item data
ShellBags Explorer (GUI)
# Launch GUI tool for interactive analysis
ShellBagsExplorer.exe
# Load registry hives: File > Load Hive
# Navigate the tree structure to see folder hierarchy
# Right-click entries for detailed shell item properties
Forensic Investigation Scenarios
Proving USB Device Browsing
Shellbag Path: My Computer\E:\Confidential\Project_Files
ShellType: Directory (on removable volume)
CreatedOn: 2025-03-15 09:30:00 UTC
This proves the user navigated to E:\Confidential\Project_Files
via Windows Explorer, even if the USB drive is no longer connected.
The volume letter E: and directory timestamps can be correlated
with USBSTOR and MountPoints2 registry entries.
Detecting Network Share Access
Shellbag Path: \\FileServer01\Finance\Q4_Reports
ShellType: Network Location
AccessedOn: 2025-02-20 14:15:00 UTC
This proves the user browsed to a network share, even if
the share has been decommissioned or access revoked.
Identifying Deleted Folder Knowledge
Shellbag Path: C:\Users\suspect\Documents\Exfiltration_Staging
ShellType: Directory
CreatedOn: 2025-01-10 08:00:00 UTC
Even though C:\Users\suspect\Documents\Exfiltration_Staging
no longer exists, the Shellbag entry proves the user
created and navigated to this folder.
Limitations
- Shellbags only record folder-level interactions, not individual file access
- Only created through Windows Explorer shell and Open/Save dialogs
- Command-line access (cmd, PowerShell) does not generate Shellbag entries
- Programmatic file access via APIs does not generate Shellbag entries
- Timestamps may reflect view setting changes, not necessarily folder access
- Windows may batch-update Shellbag entries during Explorer shutdown
References
Example Output
$ SBECmd.exe -d "C:\Evidence\Users\jsmith" --csv /analysis/shellbag_output
SBECmd v2.1.0 - ShellBags Explorer (Command Line)
====================================================
Processing hives for user: jsmith
NTUSER.DAT: C:\Evidence\Users\jsmith\NTUSER.DAT
UsrClass.dat: C:\Evidence\Users\jsmith\AppData\Local\Microsoft\Windows\UsrClass.dat
[+] NTUSER.DAT shellbag entries: 456
[+] UsrClass.dat shellbag entries: 1,234
[+] Total shellbag entries: 1,690
--- Folder Access Timeline (Incident Window) ---
Last Accessed (UTC) | Folder Path | Type | Access Count
------------------------|---------------------------------------------------------|-------------|-------------
2024-01-15 14:34:05 | C:\Users\jsmith\Downloads | File System | 45
2024-01-15 14:36:25 | C:\ProgramData\Updates | File System | 3
2024-01-15 15:05:00 | \\FILESERV01\Finance | Network | 2
2024-01-15 15:12:30 | \\FILESERV01\Finance\Q4_Reports | Network | 1
2024-01-15 15:30:00 | E:\ | Removable | 4
2024-01-15 15:30:45 | E:\Backup | Removable | 3
2024-01-15 15:31:20 | E:\Backup\Corporate_Data | Removable | 2
2024-01-15 16:12:45 | \\FILESERV01\HR\Employees | Network | 1
2024-01-15 16:15:00 | \\FILESERV01\HR\Employees\Records_2024 | Network | 1
2024-01-16 02:35:00 | C:\Windows\Temp | File System | 5
2024-01-17 02:44:00 | C:\ProgramData\svc | File System | 2
2024-01-18 01:10:00 | C:\Users\jsmith\AppData\Local\Temp | File System | 8
--- Network Share Access ---
\\FILESERV01\Finance First: 2023-09-10 Last: 2024-01-15
\\FILESERV01\Finance\Q4_Reports First: 2024-01-15 Last: 2024-01-15 (NEW)
\\FILESERV01\HR\Employees First: 2024-01-15 Last: 2024-01-15 (NEW)
\\DC01\SYSVOL First: 2023-03-15 Last: 2024-01-16 (anomalous access time)
--- Removable Device Access ---
E:\ (USB Drive)
Volume Name: BACKUP_DRIVE
First Accessed: 2024-01-15 15:30:00 UTC
Last Accessed: 2024-01-15 15:45:22 UTC
Folders Browsed: 3 (E:\, E:\Backup, E:\Backup\Corporate_Data)
--- Deleted/No Longer Existing Paths ---
C:\ProgramData\Updates\ (folder deleted, shellbag persists)
C:\ProgramData\svc\ (folder deleted, shellbag persists)
C:\Windows\Temp\tools\ (folder deleted, shellbag persists)
Summary:
Total unique folders accessed: 1,690
Network shares accessed: 4 (2 newly accessed during incident)
Removable media: 1 USB device (data staging suspected)
Deleted folder evidence: 3 paths (anti-forensics indicator)
CSV exported to: /analysis/shellbag_output/
Other files in this skill
assets/template.md (verbatim)
Shellbag Analysis Report
Case Info
| Field |
Value |
| Case Number |
|
| Examiner |
|
Folder Access Summary
| Path |
Shell Type |
Created |
Modified |
|
|
|
|
USB Device Access
| Path |
First Access |
Last Access |
|
|
|
Network Share Access
references/api-reference.md (verbatim)
API Reference: Windows ShellBag Forensics
SBECmd (Eric Zimmerman)
Syntax
SBECmd.exe -d <registry_dir> # Process directory of hives
SBECmd.exe --hive <NTUSER.DAT> # Single hive
SBECmd.exe -d <dir> --csv <output_dir> # CSV export
SBECmd.exe -d <dir> -l # Live system registry
Output Fields
| Field |
Description |
| AbsolutePath |
Full reconstructed folder path |
| CreatedOn |
Folder creation timestamp |
| ModifiedOn |
Folder modification timestamp |
| AccessedOn |
Folder access timestamp |
| MFTEntryNumber |
NTFS MFT reference |
| ShellType |
Folder, network, zip, etc. |
ShellBags Explorer (GUI)
Features
- Tree view of folder access history
- Timeline view of access patterns
- Filtering by date range
- Export to CSV/JSON
Registry Paths
NTUSER.DAT
Software\Microsoft\Windows\Shell\BagMRU
Software\Microsoft\Windows\Shell\Bags
Software\Microsoft\Windows\ShellNoRoam\BagMRU
UsrClass.dat
Local Settings\Software\Microsoft\Windows\Shell\BagMRU
Local Settings\Software\Microsoft\Windows\Shell\Bags
regipy (Python)
Installation
pip install regipy
Usage
from regipy.registry import RegistryHive
hive = RegistryHive("NTUSER.DAT")
key = hive.get_key("Software\Microsoft\Windows\Shell\BagMRU")
for value in key.iter_values():
print(value.name, type(value.value))
Shell Item Types
| Type Byte |
Description |
| 0x1F |
Root folder (GUID - Desktop, My Computer) |
| 0x2F |
Volume (drive letter) |
| 0x31 |
File entry (directory) |
| 0x32 |
File entry (file) |
| 0x41 |
Network location |
| 0x42 |
Compressed folder |
| 0x46 |
Network share (UNC path) |
| 0x71 |
Control Panel item |
Forensic Value
| Artifact |
Intelligence |
| Network paths |
Remote share access (lateral movement) |
| USB paths |
Removable media (data exfiltration) |
| Deleted folders |
Evidence of anti-forensics awareness |
| Temp directories |
Staging areas for tools/malware |
| AppData paths |
Persistence mechanism locations |
| Recycle Bin |
Awareness of deleted content |
references/standards.md (verbatim)
Standards - Shellbag Forensics
Standards
- NIST SP 800-86: Guide to Integrating Forensic Techniques
- SWGDE Best Practices for Computer Forensics
- SBECmd (Eric Zimmerman): Command-line shellbag parser
- ShellBags Explorer (Eric Zimmerman): GUI shellbag viewer
- Registry Explorer (Eric Zimmerman): Registry hive analysis
Registry Locations
- NTUSER.DAT: Software\Microsoft\Windows\Shell\BagMRU and Bags
- UsrClass.dat: Local Settings\Software\Microsoft\Windows\Shell\BagMRU and Bags
MITRE ATT&CK
- T1083 - File and Directory Discovery
- T1005 - Data from Local System
references/workflows.md (verbatim)
Workflows - Shellbag Analysis
Workflow 1: Folder Access Investigation
Extract NTUSER.DAT and UsrClass.dat from evidence
|
Parse with SBECmd to CSV
|
Open in Timeline Explorer
|
Filter by path patterns (USB drives, network shares)
|
Correlate with MFT and LNK file timestamps
|
Document folder access timeline
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