title: Behaviour-based classification of encryption-type ransomware using system calls

authors: Chew, Christopher J.W.

subjects: Ransomware

abstract: The malware landscape is ever-changing, with threat actors utilising more sophisticated techniques to compromise data. As the usage of smartphones increases, more threat actors will turn their attention to capitalise on the popularity. 

This thesis addresses this ongoing issue and focuses on encryption-type ransomware, which has been a rising malware threat in recent years, on the Android operating system. Many state-of-the-art anti-malware solutions have shifted away from static signature-based approaches as the techniques utilised by threat actors have become more advanced. Most newer solutions look towards the use of dynamic analysis to automatically identify malware. However, the large quantities of information required by dynamic analysis approaches often present a challenging task for developing robust automated anti-malware solutions and may be easily circumvented by future threat actors, which implies that more specialised automated solutions are required.

In the work presented in this thesis, we observe encryption-type ransomware behavioural patterns at a system call-level. We describe the Android Applications dataset on which a large portion of this work is based. By utilising the created dataset and the behavioural patterns, this thesis presents solutions using Finite State Machines (FSM) and supervisor reduction to quickly detect Android encryption-type ransomware. Furthermore, the solutions are evaluated on Linux encryption-type ransomware to show its transferability and generalisability.

We measured the success of our techniques by using the following accuracy metrics: true positive rates, false negative rates, true negative rates, false positive rates, and achieved an F1-score of up to 93.8%.

text: Behaviour-based classification of encryption-type ransomware using system calls The malware landscape is ever-changing, with threat actors utilising more sophisticated techniques to compromise data. As the usage of smartphones increases, more threat actors will turn their attention to capitalise on the popularity. 

This thesis addresses this ongoing issue and focuses on encryption-type ransomware, which has been a rising malware threat in recent years, on the Android operating system. Many state-of-the-art anti-malware solutions have shifted away from static signature-based approaches as the techniques utilised by threat actors have become more advanced. Most newer solutions look towards the use of dynamic analysis to automatically identify malware. However, the large quantities of information required by dynamic analysis approaches often present a challenging task for developing robust automated anti-malware solutions and may be easily circumvented by future threat actors, which implies that more specialised automated solutions are required.

In the work presented in this thesis, we observe encryption-type ransomware behavioural patterns at a system call-level. We describe the Android Applications dataset on which a large portion of this work is based. By utilising the created dataset and the behavioural patterns, this thesis presents solutions using Finite State Machines (FSM) and supervisor reduction to quickly detect Android encryption-type ransomware. Furthermore, the solutions are evaluated on Linux encryption-type ransomware to show its transferability and generalisability.

We measured the success of our techniques by using the following accuracy metrics: true positive rates, false negative rates, true negative rates, false positive rates, and achieved an F1-score of up to 93.8%.

year: 2023

title: Remote sensing of water quality in the Rotorua lakes

authors: Allan, Mathew Grant

subjects: New Zealand

abstract: The aim of this study was to determine empirical models between Landsat imagery and lake water quality variables (chlorophy11(ch1) a and Secchi depth) to enable water quality variables to be synoptically quantified. These models were then applied to past satellite images to determine temporal patterns in the spatial variation of water quality. Monitoring of lakes to determine temporal patterns in the spatial variation of water quality. Monitoring of lakes using traditional methods is expensive and lakes the ability to effectively monitor the spatial variability of water quality within and between lakes. Remote sensing can provide truly synoptic assessments of water quality, in particular the spatial distribution of phytoplankton. Recent studies monitoring lake water quality using Landsat series platforms have been successful in predicting water quality with a high accuracy. Analysis was carried out on two Landsat 7 Enhanced Thematic Mapper (ETM+) satellite images of the Rotorua lakes and Lake Taupo, for which most in situ observations were taken within two days of image capture. Regression equations were developed between the Band 1/Band 3 rations (B1/B3) from Landsat images from summer (25 Jan 2002) and spring (24 Oct 2002) and water quality variables measured in the lakes by Environment Bay of Plenty. For summer, the regression of in situ ch1 a concentration in µg/1 from ground data against the Band 1/Band 3 ratio (B1/B3) was Ln ch1 a = 14.141 – 5.0568 (B!/B3) (r² = 0.91, N=16, P<0.001). For spring, the regression equation was Ln ch1 a = 24.251-9.2806 (B1/B3) (r² = 0.83, N=13,P<0.001). Ch1 a water quality maps were than produced using these models which were also applied to other images without in situ observations near the time of image capture.

text: Remote sensing of water quality in the Rotorua lakes The aim of this study was to determine empirical models between Landsat imagery and lake water quality variables (chlorophy11(ch1) a and Secchi depth) to enable water quality variables to be synoptically quantified. These models were then applied to past satellite images to determine temporal patterns in the spatial variation of water quality. Monitoring of lakes to determine temporal patterns in the spatial variation of water quality. Monitoring of lakes using traditional methods is expensive and lakes the ability to effectively monitor the spatial variability of water quality within and between lakes. Remote sensing can provide truly synoptic assessments of water quality, in particular the spatial distribution of phytoplankton. Recent studies monitoring lake water quality using Landsat series platforms have been successful in predicting water quality with a high accuracy. Analysis was carried out on two Landsat 7 Enhanced Thematic Mapper (ETM+) satellite images of the Rotorua lakes and Lake Taupo, for which most in situ observations were taken within two days of image capture. Regression equations were developed between the Band 1/Band 3 rations (B1/B3) from Landsat images from summer (25 Jan 2002) and spring (24 Oct 2002) and water quality variables measured in the lakes by Environment Bay of Plenty. For summer, the regression of in situ ch1 a concentration in µg/1 from ground data against the Band 1/Band 3 ratio (B1/B3) was Ln ch1 a = 14.141 – 5.0568 (B!/B3) (r² = 0.91, N=16, P<0.001). For spring, the regression equation was Ln ch1 a = 24.251-9.2806 (B1/B3) (r² = 0.83, N=13,P<0.001). Ch1 a water quality maps were than produced using these models which were also applied to other images without in situ observations near the time of image capture.

year: 2007

title: The utterance, the body and the law: Seeking an approach to concretizing the sacredness of Maori language

authors: Mika, Carl Te Hira

subjects: Maori language

abstract: In what possible ways does the sacredness of a language have application in an everyday, concrete sense – in a contemporary context? If we want to discuss the sacredness of language, can we conceptualise such sacrality in anything other than an abstracted form? I will consider some places where a proposed sacredness of the Maori language might come to bear, and will particularly question its usage within the process of the law. My primary aim in this article is to conceive of ways, however hypothetical, by which the sacredness within Maori language might be removed from its current role of discursive entity and into the active life of the speaker. Thus Maori language, even in its colonized form, may once more take its own place within the spheres of the practical and the sacred at the same time.

text: The utterance, the body and the law: Seeking an approach to concretizing the sacredness of Maori language In what possible ways does the sacredness of a language have application in an everyday, concrete sense – in a contemporary context? If we want to discuss the sacredness of language, can we conceptualise such sacrality in anything other than an abstracted form? I will consider some places where a proposed sacredness of the Maori language might come to bear, and will particularly question its usage within the process of the law. My primary aim in this article is to conceive of ways, however hypothetical, by which the sacredness within Maori language might be removed from its current role of discursive entity and into the active life of the speaker. Thus Maori language, even in its colonized form, may once more take its own place within the spheres of the practical and the sacred at the same time.

year: 2007