A covert channel is a mechanism that can be used to communicate data across network or between processes within the system by violating the networks/ systems security policy and in a manner that goes unnoticed. An effective covert channel is the one that is undetectable by the adversary and can provide high degree of privacy. The goal of the covert channel is to communicate data from one host t...

The purpose of our project was the implementation of an application-layer covert channel, with guaranteed con dentiality via cha ng. A covert channel is a means of passing information between two parties in such a manner that the existence of the communication channel itself is not obvious to the casual observer. Additionally, the implementation of a covert channel is enhanced through encryptio...

Covert channels are a fundamental concept for cryptanalytic side-channel attacks. Covert timing channels use latency to carry data, and are the foundation for timing and cache-timing attacks. Covert storage channels instead utilize existing system bits to carry data, and are not historically used for cryptanalytic side-channel attacks. This paper introduces a new storage channel made available ...

Covert channels evade isolation mechanisms between multiple parties in the cloud. Especially cache covert channels allow the transmission of several hundred kilobits per second between unprivileged user programs in separate virtual machines. However, caches are small and shared and thus cache-based communication is susceptible to noise from any system activity and interrupts. The feasibility of...

We identify a class of covert timing channels with the following properties. (1) existing covert timing channel analysis techniques are inappropriate for the channels in this class; and (2) it includes the fastest (i.e., highest capacity) covert channels known to date. Since channels in this class are exploited by counting the occurrences of certain events, we call them counting channels. We de...

We define a probabilistic model for the NRL Pump and using FHP-murφ show experimentally that there exists a probabilistic covert channel whose capacity depends on various NRL Pump parameters (e.g. buffer size, number of samples in the moving average, etc).

The paper concerns available steganographic techniques that can be used for creating covert channels for VoIP (Voice over Internet Protocol) streams. Apart from characterizing existing steganographic methods we provide new insights by presenting two new techniques. The first one is network steganography solution which exploits free/unused protocols’ fields and is known for IP, UDP or TCP protoc...

We address the problem of detecting the presence of hidden messages in audio. The detector is based on the characteristics of the denoised residuals of the audio file, which may consist of a mixture of speech and music data. A set of generalized moments of the audio signal is measured in terms of objective and perceptual quality measures. The detector discriminates between cover and stego files...

Network covert channels enable a policy-breaking network communication (e.g., within botnets). Within the last years, new covert channel techniques arose which are based on the capability of protocol switching. Such protocol switching covert channels operate within overlay networks and can (as a special case) contain their own internal control protocols. We present the first approach to effecti...

A network covert channel is created that operates by modulating the time between web resource accesses, with an “average web user” read-time used as a reference. While the covert channel may be classified as timing based, it does not operate by changing deterministic protocol attributes such as inter-packet delay, as do most timing based network covert channels. Instead, our channel communicate...