Invisible Backdoor Detector

Invisible Backdoor Detector is a little Python script that allows you to spot and remove Bidi characters that could lead to an invisible backdoor. If you don't know what that is you should check the related paragraph.

Table of Contents

• Table of contents
• What is an Invisible Backdoor
• Installation and Usage
• Examples
• Contributions
• Credits
• License

What is an Invisbile Backdoor

An Invisible Backdoor is exactly what you think: a backdoor that you cannot see! It was described by Wolfgang Ettlinger at Certitude in this blog post. It leverages the presence of Unicode characters (Bidi characters) which behaves like normal spaces. In conjunction with the Javascript object destructuring those characters may allow an attacker to introduce a backdoor into an open-source project without anyone noticing it. Check out the blog post for more info.

Installation and Usage

python3 -m pip install -r requirements.txt
python3 invisible-backdoor-detector.py path 
   
     [--remove]

   

The path argument is mandatory while the --remove argument allows you to automatically remove the spotted Bidi characters

Example

The example folder provides a working example of an invisible backdoor in Node.js, you may test the script on that folder. If you want to try out the backdoor you can add the following parameter to the query string:

%E3%85%A4=
   

   

Contributions

Everyone is invited to contribute! If you are a user of the tool and have a suggestion for a new feature or a bug to report, please do so through the issue tracker.

Credits

Developed by Angelo Delicato @SecSI

License

invisible-backdoor-detector is released under the MIT LICENSE