RATatouille: A Malicious Recipe Hidden in rand-user-agent (Supply Chain Compromise)
On 5 May, 16:00 GMT+0, our automated malware analysis pipeline detected a suspicious package released, rand-user-agent@1.0.110. It detected unusual code in the package, and it wasn’t wrong. It detected signs of a supply chain attack against this legitimate package, which has about ~45.000 weekly downloads.

What is the package?
The package rand-user-agent generates randomized real user-agent strings based on their frequency of occurrence. It’s maintained by the company WebScrapingAPI (https://www.webscrapingapi.com/).
Our analysis engine detected suspicious code in the file dist/index.js. Lets check it out, here seen through the code view on npm’s site:
We’ve got a RAT (Remote Access Trojan) on our hands. Here’s an overview of it:

Behavior Overview
The script sets up a covert communication channel with a command-and-control (C2) server using socket.io-client, while exfiltrating files via axios to a second HTTP endpoint. It dynamically installs these modules if missing, hiding them in a custom .node_modules folder under the user's home directory.