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Construction of IPv6 covert channels and their impact in the information system
Lohunkov, Ivan ; Jeřábek, Jan (referee) ; Phan, Viet Anh (advisor)
This thesis focuses on the issue of covert channels using IPv6 and ICMPv6 protocols. To transmit packets between devices, we need an application written in Python and also running IDS software on the receiver side. The theoretical part treats the issues of IPv6, ICMPv6 protocols and the possibility of hidden channel transmission in them. It deals with the details of their design and possible implementations. The practical part discusses a scenario that describes how the communication between the sender of packets and their receiver will take place. It also describes how to create a hidden channel and how to send it correctly. It also describes the structure of the application, both for sending the covert channel and for decrypting it. The final chapter describes programs for creating and decrypting covert channels, their communication behavior, and their strengths and weaknesses. According to the analysis of this thesis, it can be concluded that covert channels in IPv6/ICMPv6 are not yet so well understood that they are almost non-existent. This is especially true for extension headers, which are barely used in normal communication. They may be the very source, for the transmission of hidden information. The Suricata IDS has also been able to pass most packets to the receiver without alerting the receiver that the packet is suspicious.
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Fake Data in Computer Networks
Hranický, Radek ; Veselý, Vladimír (referee) ; Polčák, Libor (advisor)
This thesis describes basic principles of lawful interception systems in computer networks and it contains an analysis of various methods of their deception. It also contains a description and implementation of two software tools. The first one is designed to demonstrate an attack on the lawful interception system. The goal is to deceive the system by hiding a transmitted message in a noise, in order to make the law enforcement agency interpret a fake message as the real one. The purpose of the second tool is to obtain the original message from data captured by the interception system.
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Hiding Data in Computer Networks
Hrebíček, Martin ; Halfar, Patrik (referee) ; Polčák, Libor (advisor)
This diploma thesis deals with hiding data in the Internet traffic. It contains a description of the law interception. Various possibilities of hiding data are mentioned. The practical part of this thesis consists of an application that hides the data of HTTP and HTTPS protocols in a fake VoIP call. The application consists of two parts: a client and a server. Data transmitted between the client and the server parts are masked as multimedia data of the VoIP call. When a user or Internet server does not transmit any data, random data are transmitted between client and server parts in order to simulate the VoIP call. Then, the thesis focuses on detection of the attack.
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