A Survey on Automated Software Vulnerability Detection Using Machine Learning and Deep Learning

Software vulnerability detection is critical in software security because it identifies potential bugs in software systems, enabling immediate remediation and mitigation measures to be implemented before they may be exploited. Automatic vulnerability identification is important because it can evaluate large codebases more efficiently than manual code auditing. Many Machine Learning (ML) and Deep Learning (DL) based models for detecting vulnerabilities in source code have been presented in recent years. However, a survey that summarises, classifies, and analyses the application of ML/DL models for vulnerability detection is missing. It may be difficult to discover gaps in existing research and potential for future improvement without a comprehensive survey. This could result in essential areas of research being overlooked or under-represented, leading to a skewed understanding of the state of the art in vulnerability detection. This work address that gap by presenting a systematic survey to characterize various features of ML/DL-based source code level software vulnerability detection approaches via five primary research questions (RQs). Specifically, our RQ1 examines the trend of publications that leverage ML/DL for vulnerability detection, including the evolution of research and the distribution of publication venues. RQ2 describes vulnerability datasets used by existing ML/DL-based models, including their sources, types, and representations, as well as analyses of the embedding techniques used by these approaches. RQ3 explores the model architectures and design assumptions of ML/DL-based vulnerability detection approaches. RQ4 summarises the type and frequency of vulnerabilities that are covered by existing studies. Lastly, RQ5 presents a list of current challenges to be researched and an outline of a potential research roadmap that highlights crucial opportunities for future work

Toward Data-Driven Discovery of Software Vulnerabilities

Over the years, Software Engineering, as a discipline, has recognized the potential for engineers to make mistakes and has incorporated processes to prevent such mistakes from becoming exploitable vulnerabilities. These processes span the spectrum from using unit/integration/fuzz testing, static/dynamic/hybrid analysis, and (automatic) patching to discover instances of vulnerabilities to leveraging data mining and machine learning to collect metrics that characterize attributes indicative of vulnerabilities. Among these processes, metrics have the potential to uncover systemic problems in the product, process, or people that could lead to vulnerabilities being introduced, rather than identifying specific instances of vulnerabilities. The insights from metrics can be used to support developers and managers in making decisions to improve the product, process, and/or people with the goal of engineering secure software. Despite empirical evidence of metrics\u27 association with historical software vulnerabilities, their adoption in the software development industry has been limited. The level of granularity at which the metrics are defined, the high false positive rate from models that use the metrics as explanatory variables, and, more importantly, the difficulty in deriving actionable intelligence from the metrics are often cited as factors that inhibit metrics\u27 adoption in practice. Our research vision is to assist software engineers in building secure software by providing a technique that generates scientific, interpretable, and actionable feedback on security as the software evolves. In this dissertation, we present our approach toward achieving this vision through (1) systematization of vulnerability discovery metrics literature, (2) unsupervised generation of metrics-informed security feedback, and (3) continuous developer-in-the-loop improvement of the feedback. We systematically reviewed the literature to enumerate metrics that have been proposed and/or evaluated to be indicative of vulnerabilities in software and to identify the validation criteria used to assess the decision-informing ability of these metrics. In addition to enumerating the metrics, we implemented a subset of these metrics as containerized microservices. We collected the metric values from six large open-source projects and assessed metrics\u27 generalizability across projects, application domains, and programming languages. We then used an unsupervised approach from literature to compute threshold values for each metric and assessed the thresholds\u27 ability to classify risk from historical vulnerabilities. We used the metrics\u27 values, thresholds, and interpretation to provide developers natural language feedback on security as they contributed changes and used a survey to assess their perception of the feedback. We initiated an open dialogue to gain an insight into their expectations from such feedback. In response to developer comments, we assessed the effectiveness of an existing vulnerability discovery approach—static analysis—and that of vulnerability discovery metrics in identifying risk from vulnerability contributing commits

Personalized First Issue Recommender for Newcomers in Open Source Projects

Many open source projects provide good first issues (GFIs) to attract and retain newcomers. Although several automated GFI recommenders have been proposed, existing recommenders are limited to recommending generic GFIs without considering differences between individual newcomers. However, we observe mismatches between generic GFIs and the diverse background of newcomers, resulting in failed attempts, discouraged onboarding, and delayed issue resolution. To address this problem, we assume that personalized first issues (PFIs) for newcomers could help reduce the mismatches. To justify the assumption, we empirically analyze 37 newcomers and their first issues resolved across multiple projects. We find that the first issues resolved by the same newcomer share similarities in task type, programming language, and project domain. These findings underscore the need for a PFI recommender to improve over state-of-the-art approaches. For that purpose, we identify features that influence newcomers' personalized selection of first issues by analyzing the relationship between possible features of the newcomers and the characteristics of the newcomers' chosen first issues. We find that the expertise preference, OSS experience, activeness, and sentiment of newcomers drive their personalized choice of the first issues. Based on these findings, we propose a Personalized First Issue Recommender (PFIRec), which employs LamdaMART to rank candidate issues for a given newcomer by leveraging the identified influential features. We evaluate PFIRec using a dataset of 68,858 issues from 100 GitHub projects. The evaluation results show that PFIRec outperforms existing first issue recommenders, potentially doubling the probability that the top recommended issue is suitable for a specific newcomer and reducing one-third of a newcomer's unsuccessful attempts to identify suitable first issues, in the median.Comment: The 38th IEEE/ACM International Conference on Automated Software Engineering (ASE 2023

Security considerations in the open source software ecosystem

Open source software plays an important role in the software supply chain, allowing stakeholders to utilize open source components as building blocks in their software, tooling, and infrastructure. But relying on the open source ecosystem introduces unique challenges, both in terms of security and trust, as well as in terms of supply chain reliability. In this dissertation, I investigate approaches, considerations, and encountered challenges of stakeholders in the context of security, privacy, and trustworthiness of the open source software supply chain. Overall, my research aims to empower and support software experts with the knowledge and resources necessary to achieve a more secure and trustworthy open source software ecosystem. In the first part of this dissertation, I describe a research study investigating the security and trust practices in open source projects by interviewing 27 owners, maintainers, and contributors from a diverse set of projects to explore their behind-the-scenes processes, guidance and policies, incident handling, and encountered challenges, finding that participants’ projects are highly diverse in terms of their deployed security measures and trust processes, as well as their underlying motivations. More on the consumer side of the open source software supply chain, I investigated the use of open source components in industry projects by interviewing 25 software developers, architects, and engineers to understand their projects’ processes, decisions, and considerations in the context of external open source code, finding that open source components play an important role in many of the industry projects, and that most projects have some form of company policy or best practice for including external code. On the side of end-user focused software, I present a study investigating the use of software obfuscation in Android applications, which is a recommended practice to protect against plagiarism and repackaging. The study leveraged a multi-pronged approach including a large-scale measurement, a developer survey, and a programming experiment, finding that only 24.92% of apps are obfuscated by their developer, that developers do not fear theft of their own apps, and have difficulties obfuscating their own apps. Lastly, to involve end users themselves, I describe a survey with 200 users of cloud office suites to investigate their security and privacy perceptions and expectations, with findings suggesting that users are generally aware of basic security implications, but lack technical knowledge for envisioning some threat models. The key findings of this dissertation include that open source projects have highly diverse security measures, trust processes, and underlying motivations. That the projects’ security and trust needs are likely best met in ways that consider their individual strengths, limitations, and project stage, especially for smaller projects with limited access to resources. That open source components play an important role in industry projects, and that those projects often have some form of company policy or best practice for including external code, but developers wish for more resources to better audit included components. This dissertation emphasizes the importance of collaboration and shared responsibility in building and maintaining the open source software ecosystem, with developers, maintainers, end users, researchers, and other stakeholders alike ensuring that the ecosystem remains a secure, trustworthy, and healthy resource for everyone to rely on

An Empirical Study of Artifacts and Security Risks in the Pre-trained Model Supply Chain

Deep neural networks achieve state-of-the-art performance on many tasks, but require increasingly complex architectures and costly training procedures. Engineers can reduce costs by reusing a pre-trained model (PTM) and fine-tuning it for their own tasks. To facilitate software reuse, engineers collaborate around model hubs, collections of PTMs and datasets organized by problem domain. Although model hubs are now comparable in popularity and size to other software ecosystems, the associated PTM supply chain has not yet been examined from a software engineering perspective. We present an empirical study of artifacts and security features in 8 model hubs. We indicate the potential threat models and show that the existing defenses are insufficient for ensuring the security of PTMs. We compare PTM and traditional supply chains, and propose directions for further measurements and tools to increase the reliability of the PTM supply chain

A Software Vulnerabilities Odysseus: Analysis, Detection, and Mitigation

Programming has become central in the development of human activities while not being immune to defaults, or bugs. Developers have developed specific methods and sequences of tests that they implement to prevent these bugs from being deployed in releases. Nonetheless, not all cases can be thought through beforehand, and automation presents limits the community attempts to overcome. As a consequence, not all bugs can be caught. These defaults are causing particular concerns in case bugs can be exploited to breach the program’s security policy. They are then called vulnerabilities and provide specific actors with undesired access to the resources a program manages. It damages the trust in the program and in its developers, and may eventually impact the adoption of the program. Hence, to attribute a specific attention to vulnerabilities appears as a natural outcome. In this regard, this PhD work targets the following three challenges: (1) The research community references those vulnerabilities, categorises them, reports and ranks their impact. As a result, analysts can learn from past vulnerabilities in specific programs and figure out new ideas to counter them. Nonetheless, the resulting quality of the lessons and the usefulness of ensuing solutions depend on the quality and the consistency of the information provided in the reports. (2) New methods to detect vulnerabilities can emerge among the teachings this monitoring provides. With responsible reporting, these detection methods can provide hardening of the programs we rely on. Additionally, in a context of computer perfor- mance gain, machine learning algorithms are increasingly adopted, providing engaging promises. (3) If some of these promises can be fulfilled, not all are not reachable today. Therefore a complementary strategy needs to be adopted while vulnerabilities evade detection up to public releases. Instead of preventing their introduction, programs can be hardened to scale down their exploitability. Increasing the complexity to exploit or lowering the impact below specific thresholds makes the presence of vulnerabilities an affordable risk for the feature provided. The history of programming development encloses the experimentation and the adoption of so-called defence mechanisms. Their goals and performances can be diverse, but their implementation in worldwide adopted programs and systems (such as the Android Open Source Project) acknowledges their pivotal position. To face these challenges, we provide the following contributions: • We provide a manual categorisation of the vulnerabilities of the worldwide adopted Android Open Source Project up to June 2020. Clarifying to adopt a vulnera- bility analysis provides consistency in the resulting data set. It facilitates the explainability of the analyses and sets up for the updatability of the resulting set of vulnerabilities. Based on this analysis, we study the evolution of AOSP’s vulnerabilities. We explore the different temporal evolutions of the vulnerabilities affecting the system for their severity, the type of vulnerability, and we provide a focus on memory corruption-related vulnerabilities. • We undertake the replication of a machine-learning based detection algorithms that, besides being part of the state-of-the-art and referenced to by ensuing works, was not available. Named VCCFinder, this algorithm implements a Support- Vector Machine and bases its training on Vulnerability-Contributing Commits and related patches for C and C++ code. Not in capacity to achieve analogous performances to the original article, we explore parameters and algorithms, and attempt to overcome the challenge provided by the over-population of unlabeled entries in the data set. We provide the community with our code and results as a replicable baseline for further improvement. • We eventually list the defence mechanisms that the Android Open Source Project incrementally implements, and we discuss how it sometimes answers comments the community addressed to the project’s developers. We further verify the extent to which specific memory corruption defence mechanisms were implemented in the binaries of different versions of Android (from API-level 10 to 28). We eventually confront the evolution of memory corruption-related vulnerabilities with the implementation timeline of related defence mechanisms

Towards an Improved Understanding of Software Vulnerability Assessment Using Data-Driven Approaches

Software Vulnerabilities (SVs) can expose software systems to cyber-attacks, potentially causing enormous financial and reputational damage for organizations. There have been significant research efforts to detect these SVs so that developers can promptly fix them. However, fixing SVs is complex and time-consuming in practice, and thus developers usually do not have sufficient time and resources to fix all SVs at once. As a result, developers often need SV information, such as exploitability, impact, and overall severity, to prioritize fixing more critical SVs. Such information required for fixing planning and prioritization is typically provided in the SV assessment step of the SV lifecycle. Recently, data-driven methods have been increasingly proposed to automate SV assessment tasks. However, there are still numerous shortcomings with the existing studies on data-driven SV assessment that would hinder their application in practice. This PhD thesis aims to contribute to the growing literature in data-driven SV assessment by investigating and addressing the constant changes in SV data as well as the lacking considerations of source code and developers’ needs for SV assessment that impede the practical applicability of the field. Particularly, we have made the following five contributions in this thesis. (1) We systematize the knowledge of data-driven SV assessment to reveal the best practices of the field and the main challenges affecting its application in practice. Subsequently, we propose various solutions to tackle these challenges to better support the real-world applications of data-driven SV assessment. (2) We first demonstrate the existence of the concept drift (changing data) issue in descriptions of SV reports that current studies have mostly used for predicting the Common Vulnerability Scoring System (CVSS) metrics. We augment report-level SV assessment models with subwords of terms extracted from SV descriptions to help the models more effectively capture the semantics of ever-increasing SVs. (3) We also identify that SV reports are usually released after SV fixing. Thus, we propose using vulnerable code to enable earlier SV assessment without waiting for SV reports. We are the first to use Machine Learning techniques to predict CVSS metrics on the function level leveraging vulnerable statements directly causing SVs and their context in code functions. The performance of our function-level SV assessment models is promising, opening up research opportunities in this new direction. (4) To facilitate continuous integration of software code nowadays, we present a novel deep multi-task learning model, DeepCVA, to simultaneously and efficiently predict multiple CVSS assessment metrics on the commit level, specifically using vulnerability-contributing commits. DeepCVA is the first work that enables practitioners to perform SV assessment as soon as vulnerable changes are added to a codebase, supporting just-in-time prioritization of SV fixing. (5) Besides code artifacts produced from a software project of interest, SV assessment tasks can also benefit from SV crowdsourcing information on developer Question and Answer (Q&A) websites. We automatically retrieve large-scale security/SVrelated posts from these Q&A websites. We then apply a topic modeling technique on these posts to distill developers’ real-world SV concerns that can be used for data-driven SV assessment. Overall, we believe that this thesis has provided evidence-based knowledge and useful guidelines for researchers and practitioners to automate SV assessment using data-driven approaches.Thesis (Ph.D.) -- University of Adelaide, School of Computer Science, 202