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Registry Hunter

🔍 Can you uncover the hidden persistence mechanism in this compromised registry?

Challenge 23 Nov 2025 Pro Exclusive Solution Available

🛡️ Master professional Windows Registry forensics techniques used by digital investigators
🔎 Learn to identify malicious persistence mechanisms hidden in system registries
💻 Discover how attackers abuse legitimate Windows features for persistence
🎯 Develop essential digital forensics skills for real-world incident response

1
Flags
5
Points
74%
Success Rate
Start Your Challenge
~1-2 min setup
Dedicated server
Private instance
Industry standard
This solution is for Flags Mode

This walkthrough explains how to hack the lab and capture the flags. For help with Learning Mode questions, use the Request Hint button next to each question.

Challenge

🔍 Registry Hunter - Complete Digital Forensics Solution

Objective: Analyze the Windows Registry export to identify malicious persistence mechanisms and extract the hidden flag from encoded PowerShell commands.
🔍 Step 1: Understanding Windows Registry Persistence

Windows Registry contains numerous locations where malware can establish persistence. Common persistence locations include:

  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run - Programs that run at user login
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce - Programs that run once at next login
  • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run - System-wide startup programs
  • Services keys - Windows services that start automatically
  • Scheduled Tasks - Tasks scheduled to run at specific times

In this challenge, we need to examine the registry export for suspicious entries that don't belong to legitimate software.

🔍 Step 2: Initial Registry Analysis

Download and open the registry export file registry_export.reg in a text editor. The file contains several registry keys and values. Look for entries in common persistence locations.

🔍 Step 3: Identifying Suspicious Entries

Analyzing each registry entry for legitimacy:

Legitimate Entries (Run Key)
  • Adobe ARM: Adobe Updater - legitimate software
  • Steam: Gaming platform - legitimate software
  • Skype for Desktop: Microsoft communication app - legitimate
Suspicious Entries
  • SecurityUpdate (Run): Uses svchost.exe but with suspicious parameters
  • SystemMaintenance (RunOnce): PowerShell with encoded command - highly suspicious
🔍 Step 4: Analyzing the Malicious PowerShell Command

The most suspicious entry is in the RunOnce key. Look for PowerShell commands with these characteristics:

Red Flags to Identify:

  • -WindowStyle Hidden: Runs PowerShell without visible window
  • -ExecutionPolicy Bypass: Bypasses PowerShell security policies
  • -EncodedCommand: Executes Base64 encoded PowerShell script
  • RunOnce location: Executes once at next login, then removes itself
🔍 Step 5: Base64 Decoding Process

The encoded command needs to be decoded to reveal its true purpose. Look for the Base64 string after the -EncodedCommand parameter.

Decoding Methods:

Method 1: Online Base64 Decoder
  1. Copy the Base64 string
  2. Use any online Base64 decoder
  3. Paste the string and decode
  4. Review the decoded PowerShell command
Method 2: Command Line
# Linux/macOS:
echo "[BASE64_STRING]" | base64 -d

# Windows PowerShell:
[System.Text.Encoding]::Unicode.GetString([System.Convert]::FromBase64String("[BASE64_STRING]"))
🔍 Step 6: Decoded Command Analysis

When decoded, the Base64 string will reveal a PowerShell command that creates a variable containing the flag.

Analysis of the Decoded Command:

  • The command creates a PowerShell variable named $flag
  • The variable contains a UUID format string
  • This represents the flag for the challenge
  • The attacker likely used this as a way to store or transmit sensitive data
🔍 Step 7: Forensics Implications

This registry entry demonstrates several important forensics concepts:

Attack Techniques Identified:
  • Registry Persistence: Using RunOnce for one-time execution
  • PowerShell Abuse: Leveraging legitimate tools for malicious purposes
  • Encoding Obfuscation: Base64 encoding to hide malicious commands
  • Execution Policy Bypass: Circumventing PowerShell security controls
🔍 Step 8: Professional Forensics Tools

In real-world investigations, forensics professionals would use specialized tools:

Registry Analysis Tools
  • Registry Explorer (Eric Zimmerman)
  • RegRipper
  • Registry Decoder
  • Volatility Framework
PowerShell Analysis
  • PowerShell_ISE
  • PowerShell Logging
  • DeepBlueCLI
  • Revoke-Obfuscation
Encoding Analysis
  • CyberChef
  • Base64 decoders
  • Hex editors
  • Custom Python scripts
🔍 Step 9: Flag Extraction Process

The complete process to extract the flag:

  1. Download: Obtain the registry_export.reg file
  2. Analyze: Examine registry keys for suspicious entries
  3. Identify: Locate the RunOnce key with encoded PowerShell
  4. Extract: Copy the Base64 encoded string
  5. Decode: Use Base64 decoder to reveal PowerShell command
  6. Extract Flag: Identify the UUID in the decoded command variable
Success: The flag will be the UUID value found in the decoded PowerShell variable assignment.
🔍 Step 10: Learning Outcomes

This challenge demonstrates several key forensics concepts:

  • Registry Forensics: Understanding Windows Registry structure and persistence locations
  • Malware Analysis: Identifying suspicious registry entries and encoded commands
  • PowerShell Security: Understanding PowerShell execution policies and bypass techniques
  • Encoding Analysis: Decoding Base64 and other encoding schemes used by attackers
  • Incident Response: Systematic approach to analyzing digital evidence
Real-World Application: These techniques are essential for digital forensics investigators, incident response teams, and malware analysts who need to understand how attackers establish persistence and hide malicious activities in Windows systems.