A comparison of exact string search algorithms for deep packet inspection
- Authors: Hunt, Kieran
- Date: 2018
- Subjects: Algorithms , Firewalls (Computer security) , Computer networks -- Security measures , Intrusion detection systems (Computer security) , Deep Packet Inspection
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60629 , vital:27807
- Description: Every day, computer networks throughout the world face a constant onslaught of attacks. To combat these, network administrators are forced to employ a multitude of mitigating measures. Devices such as firewalls and Intrusion Detection Systems are prevalent today and employ extensive Deep Packet Inspection to scrutinise each piece of network traffic. Systems such as these usually require specialised hardware to meet the demand imposed by high throughput networks. Hardware like this is extremely expensive and singular in its function. It is with this in mind that the string search algorithms are introduced. These algorithms have been proven to perform well when searching through large volumes of text and may be able to perform equally well in the context of Deep Packet Inspection. String search algorithms are designed to match a single pattern to a substring of a given piece of text. This is not unlike the heuristics employed by traditional Deep Packet Inspection systems. This research compares the performance of a large number of string search algorithms during packet processing. Deep Packet Inspection places stringent restrictions on the reliability and speed of the algorithms due to increased performance pressures. A test system had to be designed in order to properly test the string search algorithms in the context of Deep Packet Inspection. The system allowed for precise and repeatable tests of each algorithm and then for their comparison. Of the algorithms tested, the Horspool and Quick Search algorithms posted the best results for both speed and reliability. The Not So Naive and Rabin-Karp algorithms were slowest overall.
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A framework for malicious host fingerprinting using distributed network sensors
- Authors: Hunter, Samuel Oswald
- Date: 2018
- Subjects: Computer networks -- Security measures , Malware (Computer software) , Multisensor data fusion , Distributed Sensor Networks , Automated Reconnaissance Framework , Latency Based Multilateration
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60653 , vital:27811
- Description: Numerous software agents exist and are responsible for increasing volumes of malicious traffic that is observed on the Internet today. From a technical perspective the existing techniques for monitoring malicious agents and traffic were not developed to allow for the interrogation of the source of malicious traffic. This interrogation or reconnaissance would be considered active analysis as opposed to existing, mostly passive analysis. Unlike passive analysis, the active techniques are time-sensitive and their results become increasingly inaccurate as time delta between observation and interrogation increases. In addition to this, some studies had shown that the geographic separation of hosts on the Internet have resulted in pockets of different malicious agents and traffic targeting victims. As such it would be important to perform any kind of data collection over various source and in distributed IP address space. The data gathering and exposure capabilities of sensors such as honeypots and network telescopes were extended through the development of near-realtime Distributed Sensor Network modules that allowed for the near-realtime analysis of malicious traffic from distributed, heterogeneous monitoring sensors. In order to utilise the data exposed by the near-realtime Distributed Sensor Network modules an Automated Reconnaissance Framework was created, this framework was tasked with active and passive information collection and analysis of data in near-realtime and was designed from an adapted Multi Sensor Data Fusion model. The hypothesis was made that if sufficiently different characteristics of a host could be identified; combined they could act as a unique fingerprint for that host, potentially allowing for the re-identification of that host, even if its IP address had changed. To this end the concept of Latency Based Multilateration was introduced, acting as an additional metric for remote host fingerprinting. The vast amount of information gathered by the AR-Framework required the development of visualisation tools which could illustrate this data in near-realtime and also provided various degrees of interaction to accommodate human interpretation of such data. Ultimately the data collected through the application of the near-realtime Distributed Sensor Network and AR-Framework provided a unique perspective of a malicious host demographic. Allowing for new correlations to be drawn between attributes such as common open ports and operating systems, location, and inferred intent of these malicious hosts. The result of which expands our current understanding of malicious hosts on the Internet and enables further research in the area.
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NetwIOC: a framework for the automated generation of network-based IOCS for malware information sharing and defence
- Authors: Rudman, Lauren Lynne
- Date: 2018
- Subjects: Malware (Computer software) , Computer networks Security measures , Computer security , Python (Computer program language)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60639 , vital:27809
- Description: With the substantial number of new malware variants found each day, it is useful to have an efficient way to retrieve Indicators of Compromise (IOCs) from the malware in a format suitable for sharing and detection. In the past, these indicators were manually created after inspection of binary samples and network traffic. The Cuckoo Sandbox, is an existing dynamic malware analysis system which meets the requirements for the proposed framework and was extended by adding a few custom modules. This research explored a way to automate the generation of detailed network-based IOCs in a popular format which can be used for sharing. This was done through careful filtering and analysis of the PCAP hie generated by the sandbox, and placing these values into the correct type of STIX objects using Python, Through several evaluations, analysis of what type of network traffic can be expected for the creation of IOCs was conducted, including a brief ease study that examined the effect of analysis time on the number of IOCs created. Using the automatically generated IOCs to create defence and detection mechanisms for the network was evaluated and proved successful, A proof of concept sharing platform developed for the STIX IOCs is showcased at the end of the research.
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Preimages for SHA-1
- Authors: Motara, Yusuf Moosa
- Date: 2018
- Subjects: Data encryption (Computer science) , Computer security -- Software , Hashing (Computer science) , Data compression (Computer science) , Preimage , Secure Hash Algorithm 1 (SHA-1)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57885 , vital:27004
- Description: This research explores the problem of finding a preimage — an input that, when passed through a particular function, will result in a pre-specified output — for the compression function of the SHA-1 cryptographic hash. This problem is much more difficult than the problem of finding a collision for a hash function, and preimage attacks for very few popular hash functions are known. The research begins by introducing the field and giving an overview of the existing work in the area. A thorough analysis of the compression function is made, resulting in alternative formulations for both parts of the function, and both statistical and theoretical tools to determine the difficulty of the SHA-1 preimage problem. Different representations (And- Inverter Graph, Binary Decision Diagram, Conjunctive Normal Form, Constraint Satisfaction form, and Disjunctive Normal Form) and associated tools to manipulate and/or analyse these representations are then applied and explored, and results are collected and interpreted. In conclusion, the SHA-1 preimage problem remains unsolved and insoluble for the foreseeable future. The primary issue is one of efficient representation; despite a promising theoretical difficulty, both the diffusion characteristics and the depth of the tree stand in the way of efficient search. Despite this, the research served to confirm and quantify the difficulty of the problem both theoretically, using Schaefer's Theorem, and practically, in the context of different representations.
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