Executive Summary

Analysis of a suspicious .NET loader recovered from a production server identified a multi-stage execution chain that decodes embedded Portable Executable (PE) payloads and uses native Windows APIs to perform process hollowing. The loader reconstructed configuration and payload data from reversed hexadecimal text, created a suspended .NET host process, mapped a replacement image into that process, changed the thread context to the replacement entry point, and resumed execution. The injected payload then launched a PowerShell reverse-shell command. Defensive controls stopped the outbound connection before the remote shell session was established. The attempted arbitrary code execution on a production system justified a High severity classification.

Hey, it’s been a while. Today we’re diving into a multi-stage post-compromise investigation that highlights an Initial Access Broker (IAB) handing off access to a buyer. This campaign involved layered C2 infrastructure, subtle persistence mechanisms, and anti-analysis tactics across multiple remote management tools.

The initial alert stemmed from an end-user seeing a visible error message. That single artifact pulled our team down a rabbit hole, eventually revealing a complex chain of initial entry, persistence staging, and access resale.