anti-trojan-source

Detect trojan source attacks that employ unicode bidi attacks to inject malicious code

About

Detects cases of trojan source attacks that employ unicode bidi attacks to inject malicious code

If you're using ESLint:

• See: eslint-plugin-anti-trojan-source for a purpose-bulit plugin to detect anti-trojan characters.
• This plugin inspired work to create an anti-trojan rule detect-bidi-characters in eslint-plugin-security and if you're already using that security plugin then it is advised to turn on that rule.

Why is Trojan Source important?

The following publication on the topic of unicode characters attacks, dubbed Trojan Source: Invisible Vulnerabilities, has caused a lot of concern from potential supply chain attacks where adversaries are able to inject malicious code into the source code of a project, slipping by unseen in the code review process.

For more information on the topic, you're welcome to read on the official website trojansource.codes and the following source code repository which contains the source code of the publication.

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Table of Contents

• Use as a CLI
  • Detect Trojan Source attacks using file globbing
  • Detect Trojan Source attacks using file paths
  • Detect Trojan Source attacks by piping input
• Use as an eslint plugin
• Use as a library

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Use as a CLI

anti-trojan-source is an npm package that supports detecting files that contain bidirectional unicode characters in them, per the research.

Detect Trojan Source attacks using file globbing

The following command will detect all files that contain bidirectional unicode characters in them based on the file matching pattern that was provided to it:

npx anti-trojan-source --files='src/**/*.js'

If it doesn't find anything it will return with a 0 exit code and print to stdout:

[✓] No case of trojan source detected

Detect Trojan Source attacks using file paths

npx anti-trojan-source '/src/index.js' '/src/helper.js'

If it found any matching bidi unicode characters, it will return with an exit code of 1 and print to stderr:

[x] Detected cases of trojan source in the following files:
|
 - /src/index.js
 - /src/helper.js

Detect Trojan Source attacks by piping input

If you just run npx anti-trojan-source and pipe in a file contents, it will detect the bidi unicode characters in that file:

cat /src/index.js | npx anti-trojan-source

Use as an eslint plugin

Refer to the ESLint Plugin for this CLI and the README on that repository which clearly explains how to set it up: eslint-plugin-anti-trojan-source.

Use as a library

To use it as a library and pass it file contents to detect:

import { hasTrojanSource } from 'anti-trojan-source'
const isDangerous = hasTrojanSource({
  sourceText: 'if (accessLevel != "user‮ ⁦// Check if admin⁩ ⁦") {'
})

hasTrojanSource returns a boolean.

Use as a pre-commit hook

To add this tool to your project as a pre-commit hook, try this sample configuration in .pre-commit-config.yaml:

repos:
  - repo: https://github.com/lirantal/anti-trojan-source
    rev: v1.3.3  # choose the release you want
    hooks:
      - id: anti-trojan-source

Contributing

Please consult CONTRIBUTING for guidelines on contributing to this project.

Author

anti-trojan-source © Liran Tal, Released under the Apache-2.0 License.