Detailed Analysis of a Sophisticated Firefox Extension Malware

The post describes a Python tool (browser-xpi-malware-scanner.py) designed to scan Firefox extensions (.xpi files) for malicious or suspicious code. A deep dive analysis reveals a live Firefox extension using multiple evasion techniques, including steganography in PNG icons, Unicode low-byte encoding, delayed command-and-control (C2) beacons, and dynamic rule injection. The malware also employs privilege escalation, arbitrary URL redirects, and affiliate commission hijacking. A full technical breakdown with code examples is available in the linked blog post.