CIRCO Cisco Implant Raspberry Controlled Ops

In this technical hardware security session at the DEF CON 27 Packet Hacking Village, Emilio Couto details the design and deployment of CIRCO (Cisco Implant Raspberry Controlled Ops), a stealthy hardware implant built into enterprise network appliances for covert physical red teaming. He introduces the physical design at 08:00, explaining how a miniaturized Raspberry Pi is retrofitted directly inside the housing of a Cisco IP phone or switch chassis, drawing parasitic power from the internal bus and sharing internal Ethernet connections.

Emilio showcases his enterprise testing environment at 16:00, featuring Managed Cisco switches, firewalls, and 802.1X Network Access Control (NAC) infrastructure. After navigating live hardware demonstration challenges at 24:00, he demonstrates how the internal implant intercepts network traffic and seamlessly emulates legitimate Cisco Discovery Protocol (CDP) packets at 32:00, allowing the implant to mimic an authorized network device to upstream monitoring tools.

At 40:00, Emilio examines subtle network fingerprinting evasion techniques, analyzing TCP window sizes and NAT properties to prevent intrusion detection systems from identifying rogue Linux kernel packets. He demonstrates full network access at 48:00, showing how the implant circumvents port security controls by piggybacking on authenticated VoIP phone sessions to provide red teamers with persistent out-of-band network access. (AI summary — Gemini Flash)