OSI Physical Layer Protocols and Known Security Issues


The physical layer transmits raw bits over a communication channel, this layer needs to make sure that when one side sends a 1 bit it is received by the other side as a 1 bit, not as a 0 bit. Includes, but not limited to cables, jacks, and hubs. The physical layer can include everything from the cable type, radio frequency link (as in an 802.11 wireless systems), as well as the layout of pins, voltages and other physical requirements.

Protocol Data Unit


The bit is a basic unit of information used in computing and digital communications. A binary digit can only have one of two values, and may be physically represented with a two-state device. These state values are most commonly represented as either a 0 or 1.

Main Security Issues

  1. Malicious Firmware
  2. Supply Chain Security
  3. Loss of Power
  4. Loss of Environmental Control
  5. Physical Theft of Data and Hardware
  6. Physical Damage or Destruction of Data And Hardware
  7. Unauthorised changes to the functional environment (data connections, removable media, adding/removing resources)
  8. Disconnection of Physical Data Links Undetectable Interception of Data
  9. Keystroke & Other Input Logging


Uses the Protocols 100BaseT & 1000 Base-X and uses Hubs, patch panels, & RJ45 Jacks as devices.

Physical Layer OpSec

Practice defence in-depth tactics, use access controls, accountability, and auditing to track and control physical assets.