Examples of covert channels

The following are examples of covert channels that might exist in modules created by a systems programmer.

Printing service covert channel example
This is an example of a printing service covert channe.
Resource pools example
When a trusted program performs a service for an untrusted client, the trusted program allocates a specific type of resource (for example a buffer) from a pool of resources that is shared among processes at different MAC labels.
Databases example
A trusted database system allows user programs to place data into a multilevel database. Direct access is properly controlled via the basic MAC restrictions.

Parent topic: Covert channels