Covert Channels are mechanisms that allow for unauthorized information transfer between processes or systems, bypassing standard security controls. They exploit hidden or unintended communication paths to transmit data.
Types of Covert Channels:
- Storage Covert Channel:
- Mechanism: Information is conveyed through shared storage spaces that are not meant for inter-process communication. For example, processes might use shared files or memory locations to exchange secret messages.
- Example: A process writes information to a file that another process reads from, even though the file is not intended for this purpose.
- Covert Timing Channel:
- Mechanism: One process communicates with another by altering its use of system resources or timing patterns. The timing variations can be interpreted by another process to infer information.
- Example: A process might vary its CPU usage or delay its responses in a way that encodes information, such as Morse code.
Countermeasures:
- Design Considerations: Higher Evaluation Assurance Level (EAL) systems, such as EAL6, have improved defenses against covert channels compared to lower EAL levels. These systems typically include more rigorous design and analysis processes to identify and mitigate covert channels.
- Mitigation Techniques: Addressing covert channels often involves a combination of secure system design practices, thorough testing, and continuous monitoring to ensure that potential channels are identified and controlled.
Understanding and managing covert channels is crucial for ensuring that systems adhere to security requirements and prevent unauthorized information leakage.