The JFrog Security Research team recently discovered a new malware payload in the PyPI repository, written in C#. This is uncommon since PyPI is primarily a repository for Python packages, and its codebase consists mostly of Python code, or natively compiled libraries used by Python programs. This finding raised our concerns about the potential for cross-language malware attacks.

The risk of supply chain attacks increases as more companies rely on third-party vendors and suppliers for critical services and products. Supply chain attacks have become increasingly prominent in recent years. In 2022, for instance, supply chain attacks surpassed the number of malware-based attacks by 40%.

In this blog post, we’ll provide a detailed analysis of a malicious payload we’ve dubbed “Impala Stealer”, a custom crypto stealer which was used as the payload for the NuGet malicious packages campaign we’ve exposed in our previous post. The sophisticated campaign targeted.NET developers via NuGet malicious packages, and the JFrog Security team was able to detect and report it as part of our regular activity of exposing supply chain attacks.