In the context of the CISSP exam, covert channels are unauthorized communication channels that allow information to be transmitted between different security levels in a system. These channels are often hidden and exploit unintended mechanisms to transmit data, making them difficult to detect and prevent.

Types of Covert Channels

There are two primary types of covert channels:

1. Storage Channels:

Storage channels involve the use of a shared storage resource, such as a hard drive or file system, to transmit information. One process can modify the shared resource in a way that encodes data, and another process can read the resource to decode the information.

2. Timing Channels:

Timing channels exploit the timing of system events to transmit information. One process can intentionally modulate its resource usage, such as CPU time or network bandwidth, to create a timing pattern that encodes data. Another process can monitor the timing of these events to decode the information.

Covert Channel Mitigation

Covert channels can pose a significant security risk, as they can be used to exfiltrate sensitive data or compromise system integrity. To mitigate this risk, organizations should implement the following measures:

• Identify and monitor potential covert channels: Organizations should identify potential covert channels within their systems by examining shared resources and system timing patterns.

• Implement access controls: Implement strict access controls to limit the ability of processes to access shared resources or influence system timing.

• Monitor system activity: Continuously monitor system activity for suspicious patterns that could indicate covert channel activity.

• Educate and train employees: Educate employees about the risks of covert channels and train them to identify and report suspicious activity.