arXiv subjects

Giovanni Russello

Publications and source records attributed to Giovanni Russello.

At least 19 recordsLinked to original sources

arXiv2026

R+R: Reassessing Java Security API Misuse in Current LLMs: A Replication on JCA and JSSE APIs with External Security Knowledge

The misuse of Java security APIs is a serious security problem in software development. Research in 2024 has shown that this problem is widespread in LLM-generated code. However, it remains unclear whether this phenomenon persists in current models and how external security knowledge affects it. This paper presents a scoped replication and extension of Mousavi et al.'s study on the Java Cryptography Architecture (JCA) and Java Secure Socket Extension (JSSE) APIs. We focus on two complementary settings: GPT-5.5 as a frontier proprietary coding model, and Llama-3.3-70B-Instruct as a strong open-weight model relevant to self-hosted deployment. The results show that although newer LLMs perform better in using Java security APIs, the problem of Java security API misuse has not been eliminated. External security knowledge substantially improves the measured outcome, but its effect is model-dependent. For Llama-3.3-70B-Instruct, secure code examples are the most effective single knowledge type. For GPT-5.5, explicit misuse patterns eliminate all detected security API misuses among valid programs in our benchmark, although some outputs remain invalid due to compilation errors or target-API mismatches. In addition, developer-guide knowledge becomes much more effective, and secure prompting also provides large gains for GPT-5.5. Overall, these findings confirm the Java security API misuse risk identified in the original study and show that the benefits of retrieval-augmented knowledge depend not only on the knowledge itself and retrieval behavior, but also on model capability.

cs.CR↗

arXiv2025

From misinformation to climate crisis: Navigating vulnerabilities in the cyber-physical-social systems

Within the cyber-physical-social-climate nexus, all systems are deeply interdependent: cyber infrastructure facilitates communication, data processing, and automation across physical systems (such as power grids and networks), while social infrastructure provides the human capital and societal norms necessary for the system's functionality. Any disruption within any of these components, whether due to human error or system mismanagement, can propagate throughout the network, amplifying vulnerabilities and creating a significantly scaled impact. This chapter explores the critical role of human vulnerabilities within the cyber-physical-social-climate nexus, focusing on the interdependencies across cyber, physical, and social systems and how these interdependencies can scale in a climate context. While cyber and physical vulnerabilities are readily apparent, social vulnerabilities (such as misinformation, resistance to policy change, and lack of public awareness) often go unaddressed despite their profound impact on resilience and climate adaptation. Social infrastructure, including human capital, societal norms, and policy frameworks, shapes community responses and underpins adaptive capacity, yet it is also a significant point of failure when overlooked. This chapter examines how human cognitive biases, risk misperception, and decision-making silos within interconnected systems can lead to resource misallocation and weakened policy effectiveness. These factors are analyzed to demonstrate how inadequate responses across cyber-physical-social layers can cascade, amplifying climate-related risks. By addressing these human factors and aligning decision-making frameworks, we aim to strengthen resilience and foster cohesive adaptation strategies that account for the intricate interrelations of cyber-physical-social-climate systems.

cs.CR↗

arXiv2025

Guard-GBDT: Efficient Privacy-Preserving Approximated GBDT Training on Vertical Dataset

In light of increasing privacy concerns and stringent legal regulations, using secure multiparty computation (MPC) to enable collaborative GBDT model training among multiple data owners has garnered significant attention. Despite this, existing MPC-based GBDT frameworks face efficiency challenges due to high communication costs and the computation burden of non-linear operations, such as division and sigmoid calculations. In this work, we introduce Guard-GBDT, an innovative framework tailored for efficient and privacy-preserving GBDT training on vertical datasets. Guard-GBDT bypasses MPC-unfriendly division and sigmoid functions by using more streamlined approximations and reduces communication overhead by compressing the messages exchanged during gradient aggregation. We implement a prototype of Guard-GBDT and extensively evaluate its performance and accuracy on various real-world datasets. The results show that Guard-GBDT outperforms state-of-the-art HEP-XGB (CIKM'21) and SiGBDT (ASIA CCS'24) by up to $2.71\times$ and $12.21 \times$ on LAN network and up to $2.7\times$ and $8.2\times$ on WAN network. Guard-GBDT also achieves comparable accuracy with SiGBDT and plaintext XGBoost (better than HEP-XGB ), which exhibits a deviation of $\pm1\%$ to $\pm2\%$ only. Our implementation code is provided at https://github.com/XidianNSS/Guard-GBDT.git.

cs.CR↗

arXiv2025

MultiPhishGuard: An Explainable and Adaptive Multi-Agent LLM System for Phishing Email Detection

Phishing email detection faces significant challenges due to evolving adversarial tactics and heterogeneous attack patterns. Traditional approaches, such as rule-based filters and denylists, often struggle to keep pace, leading to missed detections and security risks. While machine learning methods have improved detection performance, they remain limited in adapting to novel and rapidly changing phishing strategies. We present MultiPhishGuard, an LLM-based multi-agent detection framework with learned coordination across specialized agents. The system consists of five cooperative agents (text, URL, metadata, explanation simplifier, and adversarial agents), with agent contributions dynamically weighted using Proximal Policy Optimization. To address emerging threats, the framework incorporates an adversarial training loop in which an LLM-based agent generates subtle, context-aware email variants to expose potential model weaknesses and improve robustness to ambiguous phishing cases. Experimental evaluations on public datasets show that MultiPhishGuard achieves stronger performance than established baselines, including Chain-of-Thought prompting and single-agent variants, as supported by ablation studies and comparative analyses. The system achieves an accuracy of 97.89%, with a false positive rate of 2.73% and a false negative rate of 0.20%. In addition, an explanation simplifier agent transforms technical model outputs into plain-language rationales intended for human users. Overall, these results suggest that multi-agent LLM architectures with adaptive coordination and adversarial training represent a promising direction for phishing email detection.

cs.CR↗

arXiv2025

A Novel Framework To Assess Cybersecurity Capability Maturity

In today's rapidly evolving digital landscape, organisations face escalating cyber threats that can disrupt operations, compromise sensitive data, and inflict financial and reputational harm. A key reason for this lies in the organisations' lack of a clear understanding of their cybersecurity capabilities, leading to ineffective defences. To address this gap, Cybersecurity Capability Maturity Models (CCMMs) provide a systematic approach to assessing and enhancing an organisation's cybersecurity posture by focusing on capability maturity rather than merely implementing controls. However, their limitations, such as rigid structures, one-size-fits-all approach, complexity, gaps in security scope (i.e., technological, organisational, and human aspects) and lack of quantitative metrics, hinder their effectiveness. It makes implementing CCMMs in varying contexts challenging and results in fragmented, incomprehensive assessments. Therefore, we propose a novel Cybersecurity Capability Maturity Framework that is holistic, flexible, and measurable to provide organisations with a more relevant and impactful assessment to enhance their cybersecurity posture.

cs.CR↗

arXiv2024

Exploring Content Concealment in Email

The never-ending barrage of malicious emails, such as spam and phishing, is of constant concern for users, who rely on countermeasures such as email filters to keep the intended recipient safe. Modern email filters, one of our few defence mechanisms against malicious emails, are often circumvented by sophisticated attackers. This study focuses on how attackers exploit HTML and CSS in emails to conceal arbitrary content, allowing for multiple permutations of a malicious email, some of which may evade detection by email filters. This concealed content remains undetected by the recipient, presenting a serious security risk. Our research involved developing and applying an email sampling and analysis procedure to a large-scale dataset of unsolicited emails. We then identify the sub-types of concealment attackers use to conceal content and the HTML and CSS tricks employed.

cs.CR↗

arXiv2024

Eyes on the Phish(er): Towards Understanding Users' Email Processing Pattern and Mental Models in Phishing Detection

Phishing emails typically masquerade themselves as reputable identities to trick people into providing sensitive information and credentials. Despite advancements in cybersecurity, attackers continuously adapt, posing ongoing threats to individuals and organisations. While email users are the last line of defence, they are not always well-prepared to detect phishing emails. This study examines how workload affects susceptibility to phishing, using eye-tracking technology to observe participants' reading patterns and interactions with tailored phishing emails. Incorporating both quantitative and qualitative analysis, we investigate users' attention to two phishing indicators, email sender and hyperlink URLs, and their reasons for assessing the trustworthiness of emails and falling for phishing emails. Our results provide concrete evidence that attention to the email sender can reduce phishing susceptibility. While we found no evidence that attention to the actual URL in the browser influences phishing detection, attention to the text masking links can increase phishing susceptibility. We also highlight how email relevance, familiarity, and visual presentation impact first impressions of email trustworthiness and phishing susceptibility.

cs.HC↗

arXiv2024

RAGent: Retrieval-based Access Control Policy Generation

Manually generating access control policies from an organization's high-level requirement specifications poses significant challenges. It requires laborious efforts to sift through multiple documents containing such specifications and translate their access requirements into access control policies. Also, the complexities and ambiguities of these specifications often result in errors by system administrators during the translation process, leading to data breaches. However, the automated policy generation frameworks designed to help administrators in this process are unreliable due to limitations, such as the lack of domain adaptation. Therefore, to improve the reliability of access control policy generation, we propose RAGent, a novel retrieval-based access control policy generation framework based on language models. RAGent identifies access requirements from high-level requirement specifications with an average state-of-the-art F1 score of 87.9%. Through retrieval augmented generation, RAGent then translates the identified access requirements into access control policies with an F1 score of 77.9%. Unlike existing frameworks, RAGent generates policies with complex components like purposes and conditions, in addition to subjects, actions, and resources. Moreover, RAGent automatically verifies the generated policies and iteratively refines them through a novel verification-refinement mechanism, further improving the reliability of the process by 3%, reaching the F1 score of 80.6%. We also introduce three annotated datasets for developing access control policy generation frameworks in the future, addressing the data scarcity of the domain.

cs.CR↗

arXiv2024

SoK: Identifying Limitations and Bridging Gaps of Cybersecurity Capability Maturity Models (CCMMs)

In the rapidly evolving digital landscape, where organisations are increasingly vulnerable to cybersecurity threats, Cybersecurity Capability Maturity Models (CCMMs) emerge as pivotal tools in enhancing organisational cybersecurity posture. CCMMs provide a structured framework to guide organisations in assessing their current cybersecurity capabilities, identifying critical gaps, and prioritising improvements. However, the full potential of CCMMs is often not realised due to inherent limitations within the models and challenges encountered during their implementation and adoption processes. These limitations and challenges can significantly hamper the efficacy of CCMMs in improving cybersecurity. As a result, organisations remain vulnerable to cyber threats as they may fail to identify and address critical security gaps, implement necessary improvements or allocate resources effectively. To address these limitations and challenges, conducting a thorough investigation into existing models is essential. Therefore, we conducted a Systematic Literature Review (SLR) analysing 43 publications to identify existing CCMMs, their limitations, and the challenges organisations face when implementing and adopting them. By understanding these barriers, we aim to explore avenues for enhancing the efficacy of CCMMs, ensuring they more effectively meet the cybersecurity needs of organisational entities.

cs.CR↗

arXiv2024

No Vandalism: Privacy-Preserving and Byzantine-Robust Federated Learning

Federated learning allows several clients to train one machine learning model jointly without sharing private data, providing privacy protection. However, traditional federated learning is vulnerable to poisoning attacks, which can not only decrease the model performance, but also implant malicious backdoors. In addition, direct submission of local model parameters can also lead to the privacy leakage of the training dataset. In this paper, we aim to build a privacy-preserving and Byzantine-robust federated learning scheme to provide an environment with no vandalism (NoV) against attacks from malicious participants. Specifically, we construct a model filter for poisoned local models, protecting the global model from data and model poisoning attacks. This model filter combines zero-knowledge proofs to provide further privacy protection. Then, we adopt secret sharing to provide verifiable secure aggregation, removing malicious clients that disrupting the aggregation process. Our formal analysis proves that NoV can protect data privacy and weed out Byzantine attackers. Our experiments illustrate that NoV can effectively address data and model poisoning attacks, including PGD, and outperforms other related schemes.

cs.CR↗

arXiv2023

Zero-Knowledge Proof-based Verifiable Decentralized Machine Learning in Communication Network: A Comprehensive Survey

Over recent decades, machine learning has significantly advanced network communication, enabling improved decision-making, user behavior analysis, and fault detection. Decentralized approaches, where participants exchange computation results instead of raw private data, mitigate these risks but introduce challenges related to trust and verifiability. A critical issue arises: How can one ensure the integrity and validity of computation results shared by other participants? Existing survey articles predominantly address security and privacy concerns in decentralized machine learning, whereas this survey uniquely highlights the emerging issue of verifiability. Recognizing the critical role of zero-knowledge proofs in ensuring verifiability, we present a comprehensive review of Zero-Knowledge Proof-based Verifiable Machine Learning (ZKP-VML). To clarify the research problem, we present a definition of ZKP-VML consisting of four algorithms, along with several corresponding key security properties. Besides, we provide an overview of the current research landscape by systematically organizing the research timeline and categorizing existing schemes based on their security properties. Furthermore, through an in-depth analysis of each existing scheme, we summarize their technical contributions and optimization strategies, aiming to uncover common design principles underlying ZKP-VML schemes. Building on the reviews and analysis presented, we identify current research challenges and suggest future research directions. To the best of our knowledge, this is the most comprehensive survey to date on verifiable decentralized machine learning and ZKP-VML.

cs.LG↗

arXiv2023

SoK: Access Control Policy Generation from High-level Natural Language Requirements

Administrator-centered access control failures can cause data breaches, putting organizations at risk of financial loss and reputation damage. Existing graphical policy configuration tools and automated policy generation frameworks attempt to help administrators configure and generate access control policies by avoiding such failures. However, graphical policy configuration tools are prone to human errors, making them unusable. On the other hand, automated policy generation frameworks are prone to erroneous predictions, making them unreliable. Therefore, to find ways to improve their usability and reliability, we conducted a Systematic Literature Review analyzing 49 publications, to identify those tools, frameworks, and their limitations. Identifying those limitations will help develop effective access control policy generation solutions while avoiding access control failures.

cs.CR↗

arXiv2023

Mostree : Malicious Secure Private Decision Tree Evaluation with Sublinear Communication

A private decision tree evaluation (PDTE) protocol allows a feature vector owner (FO) to classify its data using a tree model from a model owner (MO) and only reveals an inference result to the FO. This paper proposes Mostree, a PDTE protocol secure in the presence of malicious parties with sublinear communication. We design Mostree in the three-party honest-majority setting, where an (untrusted) computing party (CP) assists the FO and MO in the secure computation. We propose two low-communication oblivious selection (OS) protocols by exploiting nice properties of three-party replicated secret sharing (RSS) and distributed point function. Mostree combines OS protocols with a tree encoding method and three-party secure computation to achieve sublinear communication. We observe that most of the protocol components already maintain privacy even in the presence of a malicious adversary, and what remains to achieve is correctness. To ensure correctness, we propose a set of lightweight consistency checks and seamlessly integrate them into Mostree. As a result, Mostree achieves sublinear communication and malicious security simultaneously. We implement Mostree and compare it with the state-of-the-art. Experimental results demonstrate that Mostree is efficient and comparable to semi-honest PDTE schemes with sublinear communication. For instance, when evaluated on the MNIST dataset in a LAN setting, Mostree achieves an evaluation using approximately 768 ms with communication of around 168 KB.

cs.CR↗

arXiv2023

CryptoMask : Privacy-preserving Face Recognition

Face recognition is a widely-used technique for identification or verification, where a verifier checks whether a face image matches anyone stored in a database. However, in scenarios where the database is held by a third party, such as a cloud server, both parties are concerned about data privacy. To address this concern, we propose CryptoMask, a privacy-preserving face recognition system that employs homomorphic encryption (HE) and secure multi-party computation (MPC). We design a new encoding strategy that leverages HE properties to reduce communication costs and enable efficient similarity checks between face images, without expensive homomorphic rotation. Additionally, CryptoMask leaks less information than existing state-of-the-art approaches. CryptoMask only reveals whether there is an image matching the query or not, whereas existing approaches additionally leak sensitive intermediate distance information. We conduct extensive experiments that demonstrate CryptoMask's superior performance in terms of computation and communication. For a database with 100 million 512-dimensional face vectors, CryptoMask offers ${\thicksim}5 \times$ and ${\thicksim}144 \times$ speed-ups in terms of computation and communication, respectively.

cs.CR↗

arXiv2023

GTree: GPU-Friendly Privacy-preserving Decision Tree Training and Inference

Decision tree (DT) is a widely used machine learning model due to its versatility, speed, and interpretability. However, for privacy-sensitive applications, outsourcing DT training and inference to cloud platforms raise concerns about data privacy. Researchers have developed privacy-preserving approaches for DT training and inference using cryptographic primitives, such as Secure Multi-Party Computation (MPC). While these approaches have shown progress, they still suffer from heavy computation and communication overheads. Few recent works employ Graphical Processing Units (GPU) to improve the performance of MPC-protected deep learning. This raises a natural question: \textit{can MPC-protected DT training and inference be accelerated by GPU?} We present GTree, the first scheme that uses GPU to accelerate MPC-protected secure DT training and inference. GTree is built across 3 parties who securely and jointly perform each step of DT training and inference with GPU. Each MPC protocol in GTree is designed in a GPU-friendly version. The performance evaluation shows that GTree achieves ${\thicksim}11{\times}$ and ${\thicksim}21{\times}$ improvements in training SPECT and Adult datasets, compared to the prior most efficient CPU-based work. For inference, GTree shows its superior efficiency when the DT has less than 10 levels, which is $126\times$ faster than the prior most efficient work when inferring $10^4$ instances with a tree of 7 levels. GTree also achieves a stronger security guarantee than prior solutions, which only leaks the tree depth and size of data samples while prior solutions also leak the tree structure. With \textit{oblivious array access}, the access pattern on GPU is also protected.

cs.CR↗

arXiv2023

Zero-Knowledge Proof-based Practical Federated Learning on Blockchain

Since the concern of privacy leakage extremely discourages user participation in sharing data, federated learning has gradually become a promising technique for both academia and industry for achieving collaborative learning without leaking information about the local data. Unfortunately, most federated learning solutions cannot efficiently verify the execution of each participant's local machine learning model and protect the privacy of user data, simultaneously. In this article, we first propose a Zero-Knowledge Proof-based Federated Learning (ZKP-FL) scheme on blockchain. It leverages zero-knowledge proof for both the computation of local data and the aggregation of local model parameters, aiming to verify the computation process without requiring the plaintext of the local data. We further propose a Practical ZKP-FL (PZKP-FL) scheme to support fraction and non-linear operations. Specifically, we explore a Fraction-Integer mapping function, and use Taylor expansion to efficiently handle non-linear operations while maintaining the accuracy of the federated learning model. We also analyze the security of PZKP-FL. Performance analysis demonstrates that the whole running time of the PZKP-FL scheme is approximately less than one minute in parallel execution.

cs.CR↗

arXiv2023

What You See is Not What You Get: The Role of Email Presentation in Phishing Susceptibility

Phishing is one of the most prevalent social engineering attacks that targets both organizations and individuals. It is crucial to understand how email presentation impacts users' reactions to phishing attacks. We speculated that the device and email presentation may play a role, and, in particular, that how links are shown might influence susceptibility. Collaborating with the IT Services unit of a large organization doing a phishing training exercise, we conducted a study to explore the effects of the device and the presentation of links. Our findings indicate that mobile device and computer users were equally likely to click on unmasked links, however mobile device users were more likely to click on masked links compared to computer users. These findings suggest that link presentation plays a significant role in users' susceptibility to phishing attacks.

cs.HC↗

arXiv2022

Scalable Private Decision Tree Evaluation with Sublinear Communication

Private decision tree evaluation (PDTE) allows a decision tree holder to run a secure protocol with a feature provider. By running the protocol, the feature provider will learn a classification result. Nothing more is revealed to either party. In most existing PDTE protocols, the required communication grows exponentially with the tree's depth $d$, which is highly inefficient for large trees. This shortcoming motivated us to design a sublinear PDTE protocol with $O(d)$ communication complexity. The core of our construction is a shared oblivious selection (SOS) functionality, allowing two parties to perform a secret-shared oblivious read operation from an array. We provide two SOS protocols, both of which achieve sublinear communication and propose optimizations to further improve their efficiency. Our sublinear PDTE protocol is based on the proposed SOS functionality and we prove its security under a semi-honest adversary. We compare our protocol with the state-of-the-art, in terms of communication and computation, under various network settings. The performance evaluation shows that our protocol is practical and more scalable over large trees than existing solutions.

cs.CR↗