text: We present a taxonomy and an algebra for attack patterns on component-based operating systems. In a multilevel security scenario, where isolation of partitions containing data at different security classifications is the primary security goal and security breaches are mainly defined as undesired disclosure or modification of classified data, strict control of information flows is the ultimate goal. In order to prevent undesired information flows, we provide a classification of information flow types in a component-based operating system and, by this, possible patterns to attack the system. The systematic consideration of informations flows reveals a specific type of operating system covert channel, the covert physical channel, which connects two former isolated partitions by emitting physical signals into the computer's environment and receiving them at another interface.
  @cite_16: onfining a program during its execution so that it cannot transmit information to any other program except its caller. A set of examples attempts to stake out the boundaries of the problem. Necessary conditions for a solution are stated and informally justified.
summary: Lampson @cite_16 made a basic distinction between legitimate channels, storage channels and covert channels in operating systems, which is considerably extended in our work.