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.
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.
@cite_16
2112826387 1968836747 2775425142 789579324
Covert channels have traditionally been categorized as either storage channels or timing channels. The author questions this categorization, and discusses channels that cannot be clearly identified as either storage or timing channels, but have aspects of both. A new model of timing channels is presented, which allows for channels that have characteristics of both storage channels and timing channels, and a method is given for constructing all channels in a computer system that have timing channel characteristics. Since R.A. Kemmerer's (1982) shared resource matrix methodology has the potential to detect all channels that have storage characteristics, the two methods jointly have the capability to construct all channels in a computer system. The approach to timing channels provides a justification of specific mechanisms for reducing their bandwidth which were employed in the VAX Virtual Machine Monitor. > Operating systems and their security are the foundation to underlay and assure the security of information systems. While effective analysis and processing mechanism for covert channels inside operating systems is one of the bottleneck issues to build up operating systems of high security levels. In this paper, some methods for identification of covert channels such as syntactic information flow method, semantic information flow method, shared resources matrix method and covert flow tree method are studied at first. Then a prototype is designed and implemented to identify covert channels inside Linux kernel based on source codes by the way of integrating above methods together. The prototype is tested on the source codes of Linux kernel 2.4.18, potential covert channels are identified and analyzed from the view of application scene so that some actual covert channels are distilled and it is verified about the validity of the prototype and the related method. Finally, research work in this paper is summarized and further research directions in future are pointed out. Covert channels provide a secret communication medium between two malicious processes to exfiltrate information stealthily that violates the security policy of a system. In this paper, we demonstrate a new covert timing channel attack that exploits the CPU operating frequencies with different power governors in real system environment. In particular, we establish how two colluding processes-a trojan and a spy can modulate the CPU frequency to create a powerful, high-capacity and robust covert channel. We implement this covert channel both in a single threaded and simultaneous multi-threading (SMT) environment and show the feasibility of such a communication. Our experiments on Intel Xeon server platform demonstrate dynamic frequency scaling covert channels that can achieve up to 20 bits second. Wireless covert channels promise to exfiltrate information with high bandwidth by circumventing traditional access control mechanisms. Ideally, they are only accessible by the intended recipient and---for regular system users operators---indistinguishable from normal operation. While a number of theoretical and simulation studies exist in literature, the practical aspects of WiFi covert channels are not well understood. Yet, it is particularly the practical design and implementation aspect of wireless systems that provides attackers with the latitude to establish covert channels: the ability to operate under adverse conditions and to tolerate a high amount of signal variations. Moreover, covert physical receivers do not have to be addressed within wireless frames, but can simply eavesdrop on the transmission. In this work, we analyze the possibilities to establish covert channels in WiFi systems with emphasis on exploiting physical layer characteristics. We discuss design alternatives for selected covert channel approaches and study their feasibility in practice. By means of an extensive performance analysis, we compare the covert channel bandwidth. We further evaluate the possibility of revealing the introduced covert channels based on different detection capabilities.