The Backdoored Browser Extension: Following the C2 Beacon

A routine Chrome auto-update silently trojanized a productivity extension on a finance workstation at Halverson Logistics. The extension beaconed to an attacker C2 domain, harvested the analyst's session cookies and an API token, and exfiltrated them to a VULTR-hosted server. With no malware on disk, the proxy and firewall logs are the only trail. Walk them step by step to trace the beacon, the theft, and the exfiltration.