Alarms and Access Controlled Doors

Bill Graydon delivers a comprehensive technical overview of electronic access control systems (ACS) and intrusion detection systems (IDS), breaking down the hardware architecture, sensor mechanics, and bypass methodologies utilized during physical security assessments [00:00]. Graydon examines the standard components of secure portals, including magnetic contact switches (reed switches), request-to-exit (REX) passive infrared (PIR) motion detectors, push buttons, push crash bars, electric strikes, and electromagnetic locks (maglocks) [06:21].

The presentation explores both physical and electronic attack vectors against door sensing circuits. Graydon illustrates how attackers defeat magnetic door contacts using strong external neodymium magnets to simulate a closed door while physically opening it [13:06]. He details how alarm panels monitor sensor wiring using supervised loops with End-of-Line (EOL) resistors, explaining how single and double EOL resistor circuits detect line tampering (shorts and opens) and how pen-testers defeat supervision by measuring and bridging matching resistances onto the line [19:47]. He also addresses vulnerabilities in wireless sensors, comparing AM and FM transmission characteristics and jamming resilience [26:45].

Graydon covers bypasses against egress detection hardware, including using compressed air or thermal devices to activate REX sensors, manipulating crash bars using under-the-door tools, and exploiting maglock mechanical installations [33:42]. He reviews intrusion alarm state machines (Armed, Disarmed, Alarm) [40:28] and PIR sensor beam patterns, noting blind spots directly below sensors and along perpendicular lines of sight [47:01]. The session concludes with recommendations for physical defenders, emphasizing tamper-resistant conduit, balanced magnetic switches (BMS), and hardened egress controls.

(AI summary — Gemini Flash)