Oblivion: an open-source system for large-scale analysis of macro-based office malware

Macro-based Office files have been extensively used as infection vectors to embed malware. In particular, VBA macros allow leveraging kernel functions and system routines to execute or remotely drop malicious payloads, and they are typically heavily obfuscated to make static analysis unfeasible. Current state-of-the-art approaches focus on discriminating between malicious and benign Office files by performing static and dynamic analysis directly on obfuscated macros, focusing mainly on detection rather than reversing. Namely, the proposed methods lack an in-depth analysis of the embedded macros, thus losing valuable information about the attack families, the embedded scripts, and the contacted external resources. In this paper, we propose Oblivion, an open-source framework for large-scale analysis of Office macros, to fill in this gap. Oblivion performs instrumentation of macros and executes them in a virtualized environment to de-obfuscate and reconstruct their behavior. Moreover, it can automatically and quickly interact with macros by extracting the embedded PowerShell and non-PowerShell attacks and reconstructing the whole macro behavior. This is the main scope of our analysis: we are more interested in retrieving specific behavioural patterns than detecting maliciousness per se. We performed a large-scale analysis of more than 30,000 files that constitute a representative corpus of attacks. Results show that Oblivion could efficiently de-obfuscate malicious macros by revealing a large corpus of PowerShell and non-PowerShell attacks. We measured that this efficiency can be quantified in an analysis time of less than 1 min per sample, on average. Moreover, we characterize such attacks by pointing out frequent attack patterns and employed obfuscation strategies. We finally release the information obtained from our dataset with our tool

Evaluation Methodologies in Software Protection Research

Man-at-the-end (MATE) attackers have full control over the system on which the attacked software runs, and try to break the confidentiality or integrity of assets embedded in the software. Both companies and malware authors want to prevent such attacks. This has driven an arms race between attackers and defenders, resulting in a plethora of different protection and analysis methods. However, it remains difficult to measure the strength of protections because MATE attackers can reach their goals in many different ways and a universally accepted evaluation methodology does not exist. This survey systematically reviews the evaluation methodologies of papers on obfuscation, a major class of protections against MATE attacks. For 572 papers, we collected 113 aspects of their evaluation methodologies, ranging from sample set types and sizes, over sample treatment, to performed measurements. We provide detailed insights into how the academic state of the art evaluates both the protections and analyses thereon. In summary, there is a clear need for better evaluation methodologies. We identify nine challenges for software protection evaluations, which represent threats to the validity, reproducibility, and interpretation of research results in the context of MATE attacks

Analysis and Concealment of Malware in an Adversarial Environment

Nowadays, users and devices are rapidly growing, and there is a massive migration of data and infrastructure from physical systems to virtual ones. Moreover, people are always connected and deeply dependent on information and communications. Thanks to the massive growth of Internet of Things applications, this phenomenon also affects everyday objects such as home appliances and vehicles. This extensive interconnection implies a significant rate of potential security threats for systems, devices, and virtual identities. For this reason, malware detection and analysis is one of the most critical security topics. The used detection strategies are well suited to analyze and respond to potential threats, but they are vulnerable and can be bypassed under specific conditions. In light of this scenario, this thesis highlights the existent detection strategies and how it is possible to deceive them using malicious contents concealment strategies, such as code obfuscation and adversarial attacks. Moreover, the ultimate goal is to explore new viable ways to detect and analyze embedded malware and study the feasibility of generating adversarial attacks. In line with these two goals, in this thesis, I present two research contributions. The first one proposes a new viable way to detect and analyze the malicious contents inside Microsoft Office documents (even when concealed). The second one proposes a study about the feasibility of generating Android malicious applications capable of bypassing a real-world detection system. Firstly, I present Oblivion, a static and dynamic system for large-scale analysis of Office documents with embedded (and most of the time concealed) malicious contents. Oblivion performs instrumentation of the code and executes the Office documents in a virtualized environment to de-obfuscate and reconstruct their behavior. In particular, Oblivion can systematically extract embedded PowerShell and non-PowerShell attacks and reconstruct the employed obfuscation strategies. This research work aims to provide a scalable system that allows analysts to go beyond simple malware detection by performing a real, in-depth inspection of macros. To evaluate the system, a large-scale analysis of more than 40,000 Office documents has been performed. The attained results show that Oblivion can efficiently de-obfuscate malicious macro-files by revealing a large corpus of PowerShell and non-PowerShell attacks in a short amount of time. Then, the focus is on presenting an Android adversarial attack framework. This research work aims to understand the feasibility of generating adversarial samples specifically through the injection of Android system API calls only. In particular, the constraints necessary to generate actual adversarial samples are discussed. To evaluate the system, I employ an interpretability technique to assess the impact of specific API calls on the evasion. It is also assessed the vulnerability of the used detection system against mimicry and random noise attacks. Finally, it is proposed a basic implementation to generate concrete and working adversarial samples. The attained results suggest that injecting system API calls could be a viable strategy for attackers to generate concrete adversarial samples. This thesis aims to improve the security landscape in both the research and industrial world by exploring a hot security topic and proposing two novel research works about embedded malware. The main conclusion of this research experience is that systems and devices can be secured with the most robust security processes. At the same time, it is fundamental to improve user awareness and education in detecting and preventing possible attempts of malicious infections

Machine Learning Interpretability in Malware Detection

The ever increasing processing power of modern computers, as well as the increased availability of large and complex data sets, has led to an explosion in machine learning research. This has led to increasingly complex machine learning algorithms, such as Convolutional Neural Networks, with increasingly complex applications, such as malware detection. Recently, malware authors have become increasingly successful in bypassing traditional malware detection methods, partly due to advanced evasion techniques such as obfuscation and server-side polymorphism. Further, new programming paradigms such as fileless malware, that is malware that exist only in the main memory (RAM) of the infected host, add to the challenges faced with modern day malware detection. This has led security specialists to turn to machine learning to augment their malware detection systems. However, with this new technology comes new challenges. One of these challenges is the need for interpretability in machine learning. Machine learning interpretability is the process of giving explanations of a machine learning model\u27s predictions to humans. Rather than trying to understand everything that is learnt by the model, it is an attempt to find intuitive explanations which are simple enough and provide relevant information for downstream tasks. Cybersecurity analysts always prefer interpretable solutions because of the need to fine tune these solutions. If malware analysts can\u27t interpret the reason behind a misclassification, they will not accept the non-interpretable or black box detector. In this thesis, we provide an overview of machine learning and discuss its roll in cyber security, the challenges it faces, and potential improvements to current approaches in the literature. We showcase its necessity as a result of new computing paradigms by implementing a proof of concept fileless malware with JavaScript. We then present techniques for interpreting machine learning based detectors which leverage n-gram analysis and put forward a novel and fully interpretable approach for malware detection which uses convolutional neural networks. We also define a novel approach for evaluating the robustness of a machine learning based detector

Analysis of Crossplatform Malicious PowerShell Scripts

Diplomová práce se zabývá bezpečností nástroje PowerShell a škodlivými skripty v něm vytvořenými. Cílem práce byla analýza možnosti využít PowerShell Core k vytvoření multiplatformního škodlivého kódu. Součástí práce je testování vybraných existujících skriptů z penetračních frameworků v poslední verzi PowerShellu Core na systémech Windows, Linux a macOS. V rámci diplomové práce bylo vytvořeno a popsáno několik škodlivých skriptů, které jsou funkční na operačních systémech Windows a Linux, vybrané z nich i na macOS. V závěru práce jsou popsány konkrétní kroky, pomocí kterých je možné snížit riziko útoku.The diploma thesis deals with the security of the tool PowerShell and malicious scripts created in it. The goal of the work was an analysis of the possibility of exploiting PowerShell Core by creating multiplatform malicious code. A part of the thesis covers the testing of selected existing scripts from penetration frameworks on the latest version of PowerShell Core on Windows, Linux and macOS systems. Several malicious scripts, which run on Windows and Linux operating systems, and even some on macOS, were created and described in the scope of the study. At the end of the work, specific steps are described to reduce the risk of attack.460 - Katedra informatikyvýborn

On the malware detection problem : challenges and novel approaches

Orientador: André Ricardo Abed GrégioCoorientador: Paulo Lício de GeusTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa : Curitiba,Inclui referênciasÁrea de concentração: Ciência da ComputaçãoResumo: Software Malicioso (malware) é uma das maiores ameaças aos sistemas computacionais atuais, causando danos à imagem de indivíduos e corporações, portanto requerendo o desenvolvimento de soluções de detecção para prevenir que exemplares de malware causem danos e para permitir o uso seguro dos sistemas. Diversas iniciativas e soluções foram propostas ao longo do tempo para detectar exemplares de malware, de Anti-Vírus (AVs) a sandboxes, mas a detecção de malware de forma efetiva e eficiente ainda se mantém como um problema em aberto. Portanto, neste trabalho, me proponho a investigar alguns desafios, falácias e consequências das pesquisas em detecção de malware de modo a contribuir para o aumento da capacidade de detecção das soluções de segurança. Mais especificamente, proponho uma nova abordagem para o desenvolvimento de experimentos com malware de modo prático mas ainda científico e utilizo-me desta abordagem para investigar quatro questões relacionadas a pesquisa em detecção de malware: (i) a necessidade de se entender o contexto das infecções para permitir a detecção de ameaças em diferentes cenários; (ii) a necessidade de se desenvolver melhores métricas para a avaliação de soluções antivírus; (iii) a viabilidade de soluções com colaboração entre hardware e software para a detecção de malware de forma mais eficiente; (iv) a necessidade de predizer a ocorrência de novas ameaças de modo a permitir a resposta à incidentes de segurança de forma mais rápida.Abstract: Malware is a major threat to most current computer systems, causing image damages and financial losses to individuals and corporations, thus requiring the development of detection solutions to prevent malware to cause harm and allow safe computers usage. Many initiatives and solutions to detect malware have been proposed over time, from AntiViruses (AVs) to sandboxes, but effective and efficient malware detection remains as a still open problem. Therefore, in this work, I propose taking a look on some malware detection challenges, pitfalls and consequences to contribute towards increasing malware detection system's capabilities. More specifically, I propose a new approach to tackle malware research experiments in a practical but still scientific manner and leverage this approach to investigate four issues: (i) the need for understanding context to allow proper detection of localized threats; (ii) the need for developing better metrics for AV solutions evaluation; (iii) the feasibility of leveraging hardware-software collaboration for efficient AV implementation; and (iv) the need for predicting future threats to allow faster incident responses