Distributed detection of anomalous internet sessions

Financial service providers are moving many services online reducing their costs and facilitating customers¿ interaction. Unfortunately criminals have quickly found several ways to avoid most security measures applied to browsers and banking sites. The use of highly dangerous malware has become the most significant threat and traditional signature-detection methods are nowadays easily circumvented due to the amount of new samples and the use of sophisticated evasion techniques. Antivirus vendors and malware experts are pushed to seek for new methodologies to improve the identification and understanding of malicious applications behavior and their targets. Financial institutions are now playing an important role by deploying their own detection tools against malware that specifically affect their customers. However, most detection approaches tend to base on sequence of bytes in order to create new signatures. This thesis approach is based on new sources of information: the web logs generated from each banking session, the normal browser execution and customers mobile phone behavior. The thesis can be divided in four parts: The first part involves the introduction of the thesis along with the presentation of the problems and the methodology used to perform the experimentation. The second part describes our contributions to the research, which are based in two areas: *Server side: Weblogs analysis. We first focus on the real time detection of anomalies through the analysis of web logs and the challenges introduced due to the amount of information generated daily. We propose different techniques to detect multiple threats by deploying per user and global models in a graph based environment that will allow increase performance of a set of highly related data. *Customer side: Browser analysis. We deal with the detection of malicious behaviors from the other side of a banking session: the browser. Malware samples must interact with the browser in order to retrieve or add information. Such relation interferes with the normal behavior of the browser. We propose to develop models capable of detecting unusual patterns of function calls in order to detect if a given sample is targeting an specific financial entity. In the third part, we propose to adapt our approaches to mobile phones and Critical Infrastructures environments. The latest online banking attack techniques circumvent protection schemes such password verification systems send via SMS. Man in the Mobile attacks are capable of compromising mobile devices and gaining access to SMS traffic. Once the Transaction Authentication Number is obtained, criminals are free to make fraudulent transfers. We propose to model the behavior of the applications related messaging services to automatically detect suspicious actions. Real time detection of unwanted SMS forwarding can improve the effectiveness of second channel authentication and build on detection techniques applied to browsers and Web servers. Finally, we describe possible adaptations of our techniques to another area outside the scope of online banking: critical infrastructures, an environment with similar features since the applications involved can also be profiled. Just as financial entities, critical infrastructures are experiencing an increase in the number of cyber attacks, but the sophistication of the malware samples utilized forces to new detection approaches. The aim of the last proposal is to demonstrate the validity of out approach in different scenarios. Conclusions. Finally, we conclude with a summary of our findings and the directions for future work

A family of droids -- Android malware detection via behavioral modeling: static vs dynamic analysis

Following the increasing popularity of mobile ecosystems, cybercriminals have increasingly targeted them, designing and distributing malicious apps that steal information or cause harm to the device's owner. Aiming to counter them, detection techniques based on either static or dynamic analysis that model Android malware, have been proposed. While the pros and cons of these analysis techniques are known, they are usually compared in the context of their limitations e.g., static analysis is not able to capture runtime behaviors, full code coverage is usually not achieved during dynamic analysis, etc. Whereas, in this paper, we analyze the performance of static and dynamic analysis methods in the detection of Android malware and attempt to compare them in terms of their detection performance, using the same modeling approach. To this end, we build on MaMaDroid, a state-of-the-art detection system that relies on static analysis to create a behavioral model from the sequences of abstracted API calls. Then, aiming to apply the same technique in a dynamic analysis setting, we modify CHIMP, a platform recently proposed to crowdsource human inputs for app testing, in order to extract API calls' sequences from the traces produced while executing the app on a CHIMP virtual device. We call this system AuntieDroid and instantiate it by using both automated (Monkey) and user-generated inputs. We find that combining both static and dynamic analysis yields the best performance, with F-measure reaching 0.92. We also show that static analysis is at least as effective as dynamic analysis, depending on how apps are stimulated during execution, and, finally, investigate the reasons for inconsistent misclassifications across methods.Accepted manuscrip

Learning Fast and Slow: PROPEDEUTICA for Real-time Malware Detection

In this paper, we introduce and evaluate PROPEDEUTICA, a novel methodology and framework for efficient and effective real-time malware detection, leveraging the best of conventional machine learning (ML) and deep learning (DL) algorithms. In PROPEDEUTICA, all software processes in the system start execution subjected to a conventional ML detector for fast classification. If a piece of software receives a borderline classification, it is subjected to further analysis via more performance expensive and more accurate DL methods, via our newly proposed DL algorithm DEEPMALWARE. Further, we introduce delays to the execution of software subjected to deep learning analysis as a way to "buy time" for DL analysis and to rate-limit the impact of possible malware in the system. We evaluated PROPEDEUTICA with a set of 9,115 malware samples and 877 commonly used benign software samples from various categories for the Windows OS. Our results show that the false positive rate for conventional ML methods can reach 20%, and for modern DL methods it is usually below 6%. However, the classification time for DL can be 100X longer than conventional ML methods. PROPEDEUTICA improved the detection F1-score from 77.54% (conventional ML method) to 90.25%, and reduced the detection time by 54.86%. Further, the percentage of software subjected to DL analysis was approximately 40% on average. Further, the application of delays in software subjected to ML reduced the detection time by approximately 10%. Finally, we found and discussed a discrepancy between the detection accuracy offline (analysis after all traces are collected) and on-the-fly (analysis in tandem with trace collection). Our insights show that conventional ML and modern DL-based malware detectors in isolation cannot meet the needs of efficient and effective malware detection: high accuracy, low false positive rate, and short classification time.Comment: 17 pages, 7 figure

Techniques for the reverse engineering of banking malware

Malware attacks are a significant and frequently reported problem, adversely affecting the productivity of organisations and governments worldwide. The well-documented consequences of malware attacks include financial loss, data loss, reputation damage, infrastructure damage, theft of intellectual property, compromise of commercial negotiations, and national security risks. Mitiga-tion activities involve a significant amount of manual analysis. Therefore, there is a need for automated techniques for malware analysis to identify malicious behaviours. Research into automated techniques for malware analysis covers a wide range of activities. This thesis consists of a series of studies: an anal-ysis of banking malware families and their common behaviours, an emulated command and control environment for dynamic malware analysis, a technique to identify similar malware functions, and a technique for the detection of ransomware. An analysis of the nature of banking malware, its major malware families, behaviours, variants, and inter-relationships are provided in this thesis. In doing this, this research takes a broad view of malware analysis, starting with the implementation of the malicious behaviours through to detailed analysis using machine learning. The broad approach taken in this thesis differs from some other studies that approach malware research in a more abstract sense. A disadvantage of approaching malware research without domain knowledge, is that important methodology questions may not be considered. Large datasets of historical malware samples are available for countermea-sures research. However, due to the age of these samples, the original malware infrastructure is no longer available, often restricting malware operations to initialisation functions only. To address this absence, an emulated command and control environment is provided. This emulated environment provides full control of the malware, enabling the capabilities of the original in-the-wild operation, while enabling feature extraction for research purposes. A major focus of this thesis has been the development of a machine learn-ing function similarity method with a novel feature encoding that increases feature strength. This research develops techniques to demonstrate that the machine learning model trained on similarity features from one program can find similar functions in another, unrelated program. This finding can lead to the development of generic similar function classifiers that can be packaged and distributed in reverse engineering tools such as IDA Pro and Ghidra. Further, this research examines the use of API call features for the identi-fication of ransomware and shows that a failure to consider malware analysis domain knowledge can lead to weaknesses in experimental design. In this case, we show that existing research has difficulty in discriminating between ransomware and benign cryptographic software. This thesis by publication, has developed techniques to advance the disci-pline of malware reverse engineering, in order to minimize harm due to cyber-attacks on critical infrastructure, government institutions, and industry.Doctor of Philosoph

Static Analysis of Malicious Java Applets

In this research, we consider the problem of detecting malicious Java applets, based on static analysis. In general, dynamic analysis is more informative, but static analysis is more efficient, and hence more practical. Consequently, static analysis is preferred, provided we can obtain results comparable to those obtained using dynamic analysis. We conducted experiments with the machine learning technique, Hidden Markov Model (HMM). We show that in some cases a static technique can detect malicious Java applets with greater accuracy than previously published research that relied on dynamic analysis

A Family of Droids -- Android Malware Detection via Behavioral Modeling: Static vs Dynamic Analysis

Following the increasing popularity of mobile ecosystems, cybercriminals have increasingly targeted them, designing and distributing malicious apps that steal information or cause harm to the device's owner. Aiming to counter them, detection techniques based on either static or dynamic analysis that model Android malware, have been proposed. While the pros and cons of these analysis techniques are known, they are usually compared in the context of their limitations e.g., static analysis is not able to capture runtime behaviors, full code coverage is usually not achieved during dynamic analysis, etc. Whereas, in this paper, we analyze the performance of static and dynamic analysis methods in the detection of Android malware and attempt to compare them in terms of their detection performance, using the same modeling approach. To this end, we build on MaMaDroid, a state-of-the-art detection system that relies on static analysis to create a behavioral model from the sequences of abstracted API calls. Then, aiming to apply the same technique in a dynamic analysis setting, we modify CHIMP, a platform recently proposed to crowdsource human inputs for app testing, in order to extract API calls' sequences from the traces produced while executing the app on a CHIMP virtual device. We call this system AuntieDroid and instantiate it by using both automated (Monkey) and user-generated inputs. We find that combining both static and dynamic analysis yields the best performance, with F-measure reaching 0.92. We also show that static analysis is at least as effective as dynamic analysis, depending on how apps are stimulated during execution, and, finally, investigate the reasons for inconsistent misclassifications across methods.Comment: A preliminary version of this paper appears in the Proceedings of 16th Annual Conference on Privacy, Security and Trust (PST 2018). This is the full versio

A Deep-dive into Cryptojacking Malware: From an Empirical Analysis to a Detection Method for Computationally Weak Devices

Cryptojacking is an act of using a victim\u27s computation power without his/her consent. Unauthorized mining costs extra electricity consumption and decreases the victim host\u27s computational efficiency dramatically. In this thesis, we perform an extensive research on cryptojacking malware from every aspects. First, we present a systematic overview of cryptojacking malware based on the information obtained from the combination of academic research papers, two large cryptojacking datasets of samples, and numerous major attack instances. Second, we created a dataset of 6269 websites containing cryptomining scripts in their source codes to characterize the in-browser cryptomining ecosystem by differentiating permissioned and permissionless cryptomining samples. Third, we introduce an accurate and efficient IoT cryptojacking detection mechanism based on network traffic features that achieves an accuracy of 99%. Finally, we believe this thesis will greatly expand the scope of research and facilitate other novel solutions in the cryptojacking domain