What is a Node.js C++ addon and how can it be used in penetration testing?

A Node.js C++ addon is a dynamically linked library written in C++ that can be loaded into Node.js using the `require()` function, enabling mutual calls between JavaScript and C++ via V8 APIs. In penetration testing, attackers can encapsulate malicious payloads as C++ addons to increase the difficulty of code analysis, as described in Node.js in Penetration Testing: Using C++ Addons to Conceal Actual Code. This approach allows payloads to be implemented in C++ with minor modifications, reducing development costs.