Dependency Confusion

A dependency confusion attack or supply chain substitution attack occurs when a software installer script is tricked into pulling a malicious code file from a public repository instead of the intended file of the same name from an internal repository.

Summary

• Tools
• Methodology
  • NPM Example
• References

Tools

• visma-prodsec/confused - Tool to check for dependency confusion vulnerabilities in multiple package management systems
• synacktiv/DepFuzzer - Tool used to find dependency confusion or project where owner’s email can be takeover.

Methodology

Look for npm, pip, gem packages, the methodology is the same : you register a public package with the same name of private one used by the company and then you wait for it to be used.

• DockerHub: Dockerfile image
• JavaScript (npm): package.json
• MVN (maven): pom.xml
• PHP (composer): composer.json
• Python (pypi): requirements.txt

NPM Example

• List all the packages (ie: package.json, composer.json, …)
• Find the package missing from www.npmjs.com
• Register and create a public package with the same name
  • Package example : 0xsapra/dependency-confusion-expoit

References

• Exploiting Dependency Confusion - Aman Sapra (0xsapra) - July 2, 2021
• Dependency Confusion: How I Hacked Into Apple, Microsoft and Dozens of Other Companies - Alex Birsan - February 9, 2021
• 3 Ways to Mitigate Risk When Using Private Package Feeds - Microsoft - March 29, 2021
• $130,000+ Learn New Hacking Technique in 2021 - Dependency Confusion - Bug Bounty Reports Explained - February 22, 2021