InvisibilityCloak – A Game-Changer In C# Post-Exploitation Tools

Proof-of-concept obfuscation toolkit for C# post-exploitation tools. This will perform the below actions for a C# visual studio project.

• Change the tool name
• Change the project GUID
• Obfuscate compatible strings in source code files based on obfuscation method entered by user
• Removes one-line comments (e.g. // this is a comment)
• Remove PDB string option for compiled release .NET assembly

Blog Post

String Candidates Not Obfuscated

The below string candidates are not included in obfuscation

• Strings less than 3 characters
• Strings using string interpolation (e.g., Console.WriteLine($"Hello, {name}! Today is {date.DayOfWeek}, it's {date:HH:mm} now.");)
• Case statements as they need to be static values
• Const vars as they need to be static values
• Strings in method signatures as they need to be static values
• Line with " => " as used in switch statement and needs to be static value.
• is in an if statement when doing comparison as the values compared must be static
• Strings within Regexes
• Override strings as they need to be static values
• The below random edge cases for strings, as they have caused issues when encoding/decoding
  • String starting with or ending with '
  • ""' in the line
  • + @" in the line
  • """ in the line
  • "" in the line
  • Encoding.Unicode.GetString in the line
  • Encoding.Unicode.GetBytes in the line
  • Encoding.ASCII.GetBytes in the line
  • Line starting with " and ending with ")]. This is typically used for command line switches and needs to be static value.

Support Information

• Windows
• Linux (Debian-based systems)
• Python3

Arguments/Options

• -d, --directory – directory where your visual studio project is located
• -m, --method – obfuscation method (base64, rot13, reverse)
• -n, --name – name of your new tool
• -h, --help – help menu
• --version – get version of tool

Usage/Examples

Run InvisibilityCloak With String Obfuscation

Base64 String Obfuscation

python InvisibilityCloak.py -d /path/to/project -n "TotallyLegitTool" -m base64

python InvisibilityCloak.py -d C:\path\to\project -n "TotallyLegitTool" -m base64

ROT13 String Obfuscation

python InvisibilityCloak.py -d /path/to/project -n "TotallyLegitTool" -m rot13

python InvisibilityCloak.py -d C:\path\to\project -n "TotallyLegitTool" -m rot13

Reverse String Obfuscation

python InvisibilityCloak.py -d /path/to/project -n "TotallyLegitTool" -m reverse

python InvisibilityCloak.py -d C:\path\to\project -n "TotallyLegitTool" -m reverse

Run InvisibilityCloak Without String Obfuscation

python InvisibilityCloak.py -d /path/to/project -n "TotallyLegitTool"

python InvisibilityCloak.py -d C:\path\to\project -n "TotallyLegitTool"