Blockchain Papers

Aydin Abadi, Dan Ristea, Artem Grigor, Steven J. Murdoch

Time-Lock Puzzles (TLPs) enable a client to lock a message such that a server can unlock it only after a specified time. They have diverse applications, such as scheduled payments, secret sharing, and zero-knowledge proofs. In this work, we present a scalable TLP designed for real-world scenarios involving a large number of puzzles, where clients or servers may lack the computational resources to handle high workloads. Our contributions are both theoretical and practical. From a theoretical standpoint, we formally define the concept of a “Delegated Time-Lock Puzzle (D-TLP)”, establish its fundamental properties, and introduce an upper bound for TLPs, addressing a previously overlooked aspect. From a practical standpoint, we introduce the “Efficient Delegated Time-Lock Puzzle” (ED-TLP) protocol, which implements the D-TLP concept. This protocol enables both the client and server to securely outsource their resource-intensive tasks to third-party helpers. It enables realtime verification of solutions and guarantees their delivery within predefined time limits by integrating an upper bound and a fair payment algorithm. ED-TLP allows combining puzzles from different clients, enabling a solver to process them sequentially, significantly reducing computational resources, especially for a large number of puzzles or clients. ED-TLP is the first protocol of its kind. We have implemented ED-TLP and conducted a comprehensive analysis of its performance for up to 10,000 puzzles. The results highlight its significant efficiency in TLP applications, demonstrating that EDTLP securely delegates 99% of the client’s workload and 100% of the server’s workload with minimal overhead.

Xueshuo Xie, Haolong Wang, Zhaolong Jian, Yaozheng Fang · 6 authors

Smart contracts are widely used on the blockchain to implement complex transactions, such as decentralized applications on Ethereum. Effective vulnerability detection of large-scale smart contracts is critical, as attacks on smart contracts often cause huge economic losses. Since it is difficult to repair and update smart contracts, it is necessary to find the vulnerabilities before they are deployed. However, code analysis, which requires traversal paths, and learning methods, which require many features to be trained, are too time-consuming to detect large-scale on-chain contracts. Learning-based methods will obtain detection models from a feature space compared to code analysis methods such as symbol execution. But the existing features lack the interpretability of the detection results and training model, even worse, the large-scale feature space also affects the efficiency of detection. This paper focuses on improving the detection efficiency by reducing the dimension of the features, combined with expert knowledge. In this paper, a feature extraction model Block-gram is proposed to form low-dimensional knowledge-based features from bytecode. First, the metadata is separated and the runtime code is converted into a sequence of opcodes, which are divided into segments based on some instructions (jumps, etc.). Then, scalable Block-gram features, including 4-dimensional block features and 8-dimensional attribute features, are mined for the learning-based model training. Finally, feature contributions are calculated from SHAP values to measure the relationship between our features and the results of the detection model. In addition, six types of vulnerability labels are made on a dataset containing 33,885 contracts, and these knowledge-based features are evaluated using seven state-of-the-art learning algorithms, which show that the average detection latency speeds up 25× to 650×, compared with the features extracted by N-gram, and also can enhance the interpretability of the detection model.

Yimika Erinle, Yathin Kethepalli, Yebo Feng, Jiahua Xu

With the advent of decentralised digital currencies powered by blockchain technology, a new era of peer-to-peer transactions has commenced. The rapid growth of the cryptocurrency economy has led to increased use of transaction-enabling wallets, making them a focal point for security risks. As the frequency of wallet-related incidents rises, there is a critical need for a systematic approach to measure and evaluate these attacks, drawing lessons from past incidents to enhance wallet security. In response, we introduce a multi-dimensional design taxonomy for existing and novel wallets with various design decisions. We classify existing industry wallets based on this taxonomy, identify previously occurring vulnerabilities and discuss the security implications of design decisions. We also systematise threats to the wallet mechanism and analyse the adversary's goals, capabilities and required knowledge. We present a multi-layered attack framework and investigate 84 incidents between 2012 and 2024, accounting for $5.4B. Following this, we classify defence implementations for these attacks on the precautionary and remedial axes. We map the mechanism and design decisions to vulnerabilities, attacks, and possible defence methods to discuss various insights.

Pengcheng, Peng, Yun, Qingzhao · 10 authors

The increased adoption of smart contracts in many industries has made them an attractive target for cybercriminals, leading to millions of dollars in losses. Thus, deploying smart contracts with detected vulnerabilities (known to developers) are not acceptable, and fixing all the detected vulnerabilities is needed, which incurs high manual labor cost without effective tool support. To fill this need, in this paper, we propose ContractFix, a novel framework that automatically generates security patches for vulnerable smart contracts. ContractFix is a general framework that can incorporate different fix patterns for different types of vulnerabilities. Users can use it as a security fix-it tool that automatically applies patches and verifies the patched contracts before deploying the contracts. To address the unique challenges in fixing smart contract vulnerabilities, given an input smart contract, \tool conducts our proposed ensemble identification based on multiple static verification tools to identify vulnerabilities that are amenable for automatic fix. Then, ContractFix generates patches using template-based fix patterns and conducts program analysis (program dependency computation and pointer analysis) for smart contracts to accurately infer and populate the parameter values for the fix patterns. Finally, ContractFix performs static verification that guarantees the patched contract is free of vulnerabilities. Our evaluations on $144$ real vulnerable contracts demonstrate that \tool can successfully fix $94\%$ of the detected vulnerabilities ($565$ out of $601$) and preserve the expected behaviors of the smart contracts.

Christoph Sendner, Ruisi Zhang, Alexander Hefter, Alexandra Dmitrienko · 5 authors

Due to the immutable and decentralized nature of Ethereum (ETH) platform, smart contracts are prone to security risks that can result in financial loss. While existing machine learning-based vulnerability detection algorithms achieve high accuracy at the contract level, they require developers to manually inspect source code to locate bugs. To this end, we present G-Scan, the first end-to-end fine-grained line-level vulnerability detection system evaluated on the first-of-its-kind real world dataset. G-Scan first converts smart contracts to code graphs in a dependency and hierarchy preserving manner. Next, we train a graph neural network to identify vulnerable nodes and assess security risks. Finally, the code graphs with node vulnerability predictions are mapped back to the smart contracts for line-level localization. We train and evaluate G-Scan on a collected real world smart contracts dataset with line-level annotations on reentrancy vulnerability, one of the most common and severe types of smart contract vulnerabilities. With the well-designed graph representation and high-quality dataset, G-Scan achieves 93.02% F1-score in contract-level vulnerability detection and 93.69% F1-score in line-level vulnerability localization. Additionally, the lightweight graph neural network enables G-Scan to localize vulnerabilities in 6.1k lines of code smart contract within 1.2 seconds.

Mingxi Ye, Yuhong Nan, Zibin Zheng, Dongpeng Wu · 5 authors

Decentralized applications (DApps) consist of multiple smart contracts running on Blockchain. With the increasing popularity of the DApp ecosystem, vulnerabilities in DApps could bring significant impacts such as financial losses. Identifying vulnerabilities in DApps is by no means trivial, as modern DApps consist of complex interactions across multiple contracts. Previous research suffers from either high false positives or false negatives, due to the lack of precise contextual information which is mandatory for confirming smart contract vulnerabilities when analyzing smart contracts.

Yu Pan, Zhichao Xu, Levi Taiji Li, Yunhe Yang · 5 authors

Smart contract and DApp users are taking great risks, as they do not obtain necessary knowledge that can help them avoid using vulnera- ble and malicious contract code. In this paper, we develop a novel system Tx2TXT that can automatically create security-centric textual descriptions directly from smart contract bytecode. To capture the security aspect of financial applications, we formally define a funds transfer graph to model critical funds flows in smart contracts. To ensure the expressiveness and conciseness of the descriptions de- rived from these graphs, we employ a GCN-based model to identify security-related condition statements and selectively add them to our graph models. To convert low-level bytecode instructions to human- readable textual scripts, we leverage robust API signatures to recover bytecode semantics. We have evaluated Tx2TXT on 890 well-labeled vulnerable, malicious and safe contracts where developer-crafted descriptions are available. Our results have shown that Tx2TXT out- performs state-of-the-art solutions and can effectively help end users avoid risky contracts

Malaw Ndiaye, Thierno Ahmadou Diallo, Karim Konaté

Smart contract is the building block of blockchain systems that enables automated peer-to-peer transactions and decentralized services. Smart contracts certainly provide a powerful functional surplus for maintaining the consistency of transactions in applications governed by blockchain technology. Smart contracts have become lucrative and profitable targets for attackers because they can hold a large amount of money. Formal verification and symbolic analysis have been employed to combat these destructive scams by analyzing the codes and function calls, yet each scam's vulnerability should be discreetly predefined. In this work, we introduce ADEFGuard, a new anomaly detection framework based on the behavior of smart contracts, as new features. We design a learning and monitoring module to determine fraudulent smart contract behaviors. Our framework is advantageous over basic algorithms in three aspects. First, ADEFGuard provides a unified solution to different genres of scams, relieving the need for code analysis skills. Second, ADEFGuard's inference is orders of magnitude faster than code analysis. Third, experimental results show that ADEFGuard achieves high accuracy (85%), precision (75%) and recall (90%) for malicious contracts and is potentially useful in detecting new malicious behaviors of smart contracts.

Yichuan Wang, Jingjing Zhao, Yaling Zhang, Xinhong Hei · 5 authors

In recent years, with the continuous promotion of blockchain technology, the application of smart contracts has shown an explosive growth trend, and smart contract vulnerabilities seriously threaten the ecological security of blockchain. Aiming at the inefficiency of existing smart contract Symbolic Execution vulnerability detection technology, this paper proposes an effective smart contract vulnerability detection method at the source code level. Firstly, we define the critical path. As attackers typically aim to steal or freeze funds, we define the path related to fund transfer as the critical path, and its related instructions are the critical instructions. Then, we constructed a smart contract control flowchart based on Ethereum bytecode and used a constraint solver to solve path constraints and corresponding vulnerability constraints. Detect common smart contract vulnerabilities such as reentrancy, access control, arithmetic vulnerabilities, unchecked low calls, and denial of service. The experimental results show that the proposed scheme has good detection performance, and vulnerability detection was performed on 55 smart contracts containing vulnerabilities in the dataset. Compared with the pre optimized scheme, the precision rate of this scheme has been improved by 7.52%, and the total execution time has been reduced by 34.92%.

Alexandre Mota, Fei Yang, Cristiano da Silva Teixeira

Nowadays, smart contracts have become increasingly popular and, as with software development in general, testing is the standard method for verifying their correctness. However, smart contracts require a higher level of certainty regarding correctness because they are diffcult to modify once deployed and errors can result in significant financial losses. Therefore, formal verification is essential. In this article, we present our search for a tool capable of formally verifying a real-world smart contract written in a recent version of Solidity.

Xueyan Tang, Yuying Du, Alan Lai, Ze Zhang · 5 authors

<title>Abstract</title> This paper aims to explore the application of deep learning in smart contract vulnerabilities detection. Smart contracts are an essential part of blockchain technology and are crucial for developing decentralized applications. However, smart contract vulnerabilities can cause financial losses and system crashes. Static analysis tools are frequently used to detect vulnerabilities in smart contracts, but they often result in false positives and false negatives because of their high reliance on predefined rules and lack of semantic analysis capabilities. Furthermore, these predefined rules quickly become obsolete and fail to adapt or generalize to new data. In contrast, deep learning methods do not require predefined detection rules and can learn the features of vulnerabilities during the training process.In this paper, we introduce a solution called Lighting Cat which is based on deep learning techniques. We trained three deep learning models for detecting vulnerabilities in smart contract: Optimized-CodeBERT, Optimized-LSTM, and Optimized-CNN. To precisely extract vulnerability features, we acquired segments of vulnerable code functions to retain critical vulnerability features. Using the CodeBERT pre-training model for data preprocessing, we could capture the syntax and semantics of the code more accurately, thereby enhancing the performance of vulnerabilities detection. This is particularly significant in the inspection of Solidity Code.To demonstrate the feasibility of our proposed solution, we evaluated its performance using the SolidiFI-benchmark dataset, which consists of 9369 vulnerable contracts injected with vulnerabilities from seven different types. Experimental results showed that, among the Lighting Cat we proposed, Optimized-CodeBERT model surpassed other methods, achieving an f1-score of 93.53%.

Pengxiang Ma, Ningyu He, Yuhua Huang, Haoyu Wang · 5 authors

Smart contracts play a vital role in the Ethereum ecosystem. Due to the prevalence of kinds of security issues in smart contracts, the smart contract verification is urgently needed, which is the process of matching a smart contract's source code to its on-chain bytecode for gaining mutual trust between smart contract developers and users. Although smart contract verification services are embedded in both popular Ethereum browsers (e.g., Etherscan and Blockscout) and official platforms (i.e., Sourcify), and gain great popularity in the ecosystem, their security and trustworthiness remain unclear. To fill the void, we present the first comprehensive security analysis of smart contract verification services in the wild. By diving into the detailed workflow of existing verifiers, we have summarized the key security properties that should be met, and observed eight types of vulnerabilities that can break the verification. Further, we propose a series of detection and exploitation methods to reveal the presence of vulnerabilities in the most popular services, and uncover 19 exploitable vulnerabilities in total. All the studied smart contract verification services can be abused to help spread malicious smart contracts, and we have already observed the presence of using this kind of tricks for scamming by attackers. It is hence urgent for our community to take actions to detect and mitigate security issues related to smart contract verification, a key component of the Ethereum smart contract ecosystem.

Rongwei Yu, Yuhang Zhang, Yong Wang, Chen Liu

Smart contract vulnerability can be exploited to cause serious financial loss. While there are many logic-based techniques for detecting vulnerabilities, few have focused on the dynamic stack of the Ethereum virtual machine (EVM) in the process of transactions. This motivates us to raise an intriguing question: What will happen when the dynamic EVM stack meets a transaction for smart contract vulnerability detection? To answer it, we propose a novel data-driven framework, dubbed TxMirror, to detect smart contract vulnerability at the bytecode level by simulating transactions symmetrically. Beyond logic-based wisdom, TxMirror customizes EVM for smart contract vulnerability detection, and stores its dependency between the stack data and logic relation in a new manner, that is, all the data are stored in a double link forest and can index the logic that creates them; it directly inspects customized EVM stack data in a transaction without replaying history transactions repeatedly or recording EVM bytecode-level traces. Furthermore, it extends detection rules defined by user interests, possessing good adaptability for developers. Extensive experiments demonstrate that TxMirror effectively detects attacks and vulnerabilities in unpredictable smart contracts.

Xiguo Gu, Huiwen Yang, Shifan Liu, Zhanqi Cui

Smart contracts are programs running on the blockchain.In recent years, due to the continuous occurrence of smart contract security accidents, how to effectively detect vulnerabilities in smart contracts has received extensive attention.Machine learning-based vulnerability detection techniques have the advantage of not requiring expert rules.However, existing approaches have limitations in identifying vulnerabilities caused by version updates of smart contract compilers.In this paper, we propose OC-Detector, a smart contract vulnerabilities detection approach based on opcode instruction clustering.OC-Detector learns the characteristics of opcode instructions to cluster them and replaces opcode instructions belonging to the same cluster with the cluster number.After that, the similarity is calculated against the contract in the vulnerability database to identify vulnerabilities.Experimental results demonstrate that OC-Detector improves the F 1 value of detecting vulnerabilities from 0.04 to 0.40 compared to DC-Hunter, Securify, SmartCheck, and Osiris.Additionally, compared to DC-Hunter, F 1 value is improved by 0.27 when detecting vulnerabilities in smart contracts compiled by different version compilers.

Jia Sui, Chu Lili, Han Bao

Aiming at the problem of insufficient technology for detecting smart contract vulnerabilities and the lack of improvement of certain detection tools, a method for the expansion and improvement of the internal module of the Mythril method is proposed. Since the technology of detecting vulnerabilities is not yet mature and there are vulnerabilities in smart contracts, vulnerability detection is particularly important. Since the Mythril tool covers the most types of vulnerabilities, its accuracy rate is also the highest. In order to ensure the effect of smart contract vulnerability detection, this paper proposes the expansion and improvement of the internal module of Mythril, which realizes the operation of automatic vulnerability analysis when performing vulnerability detection by improving the operation efficiency and simplifying the operation of smart contract opcodes while analyzing them. The comparison of experimental results shows that the proposed method is more suitable for smart contract vulnerability detection, and the detection accuracy and efficiency are improved, with an average accuracy rate of 94.07%. It performs better in vulnerability detection and provides an effective guarantee for the security and reliability of smart contracts, which has important application value and research significance.

Chaofan Shou, Shangyin Tan, Koushik Sen

Smart contracts are critical financial instruments, and their security is of utmost importance. However, smart contract programs are difficult to fuzz due to the persistent blockchain state behind all transactions. Mutating sequences of transactions are complex and often lead to a suboptimal exploration for both input and program spaces. In this paper, we introduce a novel snapshot-based fuzzer ItyFuzz for testing smart contracts. In ItyFuzz, instead of storing sequences of transactions and mutating from them, we snapshot states and singleton transactions. To explore interesting states, ItyFuzz introduces a dataflow waypoint mechanism to identify states with more potential momentum. ItyFuzz also incorporates comparison waypoints to prune the space of states. By maintaining snapshots of the states, ItyFuzz can synthesize concrete exploits like reentrancy attacks quickly. Because ItyFuzz has second-level response time to test a smart contract, it can be used for on-chain testing, which has many benefits compared to local development testing. Finally, we evaluate ItyFuzz on real-world smart contracts and some hacked on-chain DeFi projects. ItyFuzz outperforms existing fuzzers in terms of instructional coverage and can find and generate realistic exploits for on-chain projects quickly.

G. Ragu, S. Ramamoorthy

Digital forensics has intelligently evolved into cloud forensics, which protects against cybercrime. However, centralized evidence gathering and maintenance reduces the credibility of digital evidence. This article suggests a unique digital forensic architecture for the Infrastructure as a Service (IaaS) cloud combining rapidly expanding Software Defined Networking (SDN) and Blockchain technologies to address this serious issue. Blockchain helps to store the gathered evidence, which means it is shared among many peers in the proposed forensic architecture. The Secure-Ring-Verification-based Authentication (SRVA) technique is recommended to ensure security from suspicious accounts. The Harmony Search Optimization (HSO) technique helps to produce secret keys that strengthen the cloud environment. Depending on their level of sensitivity, all information is encrypted and kept on a cloud server. Sensitive Aware Deep Elliptic Curve Cryptography (SAD-ECC) method was used for encryption. In the cloud, a piece of information is saved, and the SDN manager creates the blocks and stores the history of that piece of data as metadata. Utilizing Secure Hashing Algorithm-3 (SHA-3), a Merkle Hash Tree is constructed for each block. The proposed technology uses Fuzzy-based Smart Contracts (FSCs) to enable clients to trail their data. At last, evidence analysis is made possible by creating a Logical-Graph of Evidence (LGoE) using data collected through Blockchain. The network simulator-3.26 and java (for cloud and Blockchain) environment are used for experiments. A thorough investigation shows that the suggested forensic architecture exhibits favorable response, evidence insertion, and verification times.

ウィジェスンダラ。ムディヤンセラゲ。アヌシカ・バンダラ。 ウィジェスンダラ, Wijesundara Mudiyanselage Anushka Bandara Wijesundara, 李中淳, Joong-Sun Lee · 12 authors

Abstract With the increase of IoT devices generating large amounts of user-sensitive data, improper firmware harms users’ security and privacy. Latest home appliances are integrated with features to assure compatibility with smart home IoT. However, applying complex security mechanisms to IoT is limited by device hardware capabilities, making them vulnerable to attacks. Such attacks have recently become frequent. To address this issue, we developed a secure verification mechanism for firmware released by the device’s manufacturer. We proposed an IoT gateway for secure firmware verification and updating for smart home IoT devices utilizing the IOTA MAM (Masked Authenticated Messaging) protocol and a distributed file system with IPFS (Inter-Planetary File System) protocol. These two communication protocols ensure decentralized communication and firmware file distribution between the IoT device vendor and the IoT end device. The proposed scheme securely shares latest firmware content over IOTA and IPFS networks, performs a secure firmware update on IoT end devices and ensures authenticity and integrity of the firmware. Two types of validation methods were proposed for firmware updating and validation. We implemented the proposed scheme using three entities, Vendor, IoT gateway, and IoT end device. Our system yielded promising results in performing secure automated firmware updates on IoT end devices with very low computational power. The system’s functionality was implemented using IOTA’s MAM run on Raspberry Pi as an IoT gateway along with an ESP8266 Wi-Fi microcontroller, demonstrating the effectiveness of our approach. Our proposed methodology can be used for secure firmware distribution on home IoT applications.

Isaac David, Liyi Zhou, Kaihua Qin, Dawn Song · 6 authors

We investigate the feasibility of employing large language models (LLMs) for conducting the security audit of smart contracts, a traditionally time-consuming and costly process. Our research focuses on the optimization of prompt engineering for enhanced security analysis, and we evaluate the performance and accuracy of LLMs using a benchmark dataset comprising 52 Decentralized Finance (DeFi) smart contracts that have previously been compromised. Our findings reveal that, when applied to vulnerable contracts, both GPT-4 and Claude models correctly identify the vulnerability type in 40% of the cases. However, these models also demonstrate a high false positive rate, necessitating continued involvement from manual auditors. The LLMs tested outperform a random model by 20% in terms of F1-score. To ensure the integrity of our study, we conduct mutation testing on five newly developed and ostensibly secure smart contracts, into which we manually insert two and 15 vulnerabilities each. This testing yielded a remarkable best-case 78.7% true positive rate for the GPT-4-32k model. We tested both, asking the models to perform a binary classification on whether a contract is vulnerable, and a non-binary prompt. We also examined the influence of model temperature variations and context length on the LLM's performance. Despite the potential for many further enhancements, this work lays the groundwork for a more efficient and economical approach to smart contract security audits.

Kai Li, Darren Lee, Shixuan Guan

This paper presents a comprehensive analysis of the cryptocurrency free giveaway scam disseminated in a new distribution channel, Twitter lists. To collect and detect the scam in this channel, unlike existing scam detection systems that rely on manual effort, this paper develops a fully automated scam detection system, \textit{GiveawayScamHunter}, to continuously collect lists from Twitter and utilize a Nature-Language-Processing (NLP) model to automatically detect the free giveaway scam and extract the scam cryptocurrency address. By running \textit{GiveawayScamHunter} from June 2022 to June 2023, we detected 95,111 free giveaway scam lists on Twitter that were created by thousands of Twitter accounts. Through analyzing the list creator accounts, our work reveals that scammers have combined different strategies to spread the scam, including compromising popular accounts and creating spam accounts on Twitter. Our analysis result shows that 43.9\% of spam accounts still remain active as of this writing. Furthermore, we collected 327 free giveaway domains and 121 new scam cryptocurrency addresses. By tracking the transactions of the scam cryptocurrency addresses, this work uncovers that over 365 victims have been attacked by the scam, resulting in an estimated financial loss of 872K USD. Overall, this work sheds light on the tactics, scale, and impact of free giveaway scams disseminated on Twitter lists, emphasizing the urgent need for effective detection and prevention mechanisms to protect social media users from such fraudulent activity.

Sahil Dudani, Ibrahim Baggili, David Raymond, Randolph Marchany

No abstract is available for this record.

V. Maheshwari, M. Prasanna

Blockchain is a decentralized, distributed ledger that records transactions between two parties. A blockchain-based software system is a new and innovative approach to software engineering that uses blockchain technology. This approach has several advantages over traditional software engineering approaches, including improved security and transparency. The most common software engineering approaches are waterfall, agile and hybrid models. Each of these has its strengths and weakness. A blockchain-based system has the advantage of being more secure and transparent than any of these approaches. It also can track changes more accurately, which can improve quality control. Blockchain technologies have incredible potential but also have some problems. One problem is security and privacy issues, which brings into question the resilience of existing security and trust mechanisms. The distributed application (dApp) framework for the proposed electronic voting system is built with the help of blockchain technology in this proposal. As a result, fewer crimes has committed against sensitive data during the electoral process because of immutability, transparency and privacy. Ganache, Metamask and hashing algorithms are used to develop the dApp. The paper's strengths lie in its ability to create and analyze threat models for blockchain-enabled-electronic voting systems and to identify the types of threats using Microsoft STRIDE.

Monika di Angelo, Thomas Durieux, João F. Ferreira, Gernot Salzer

Smart contracts are blockchain programs that often handle valuable assets. Writing secure smart contracts is far from trivial, and any vulnerability may lead to significant financial losses. To support developers in identifying and eliminating vulnerabilities, methods and tools for the automated analysis of smart contracts have been proposed. However, the lack of commonly accepted benchmark suites and performance metrics makes it difficult to compare and evaluate such tools. Moreover, the tools are heterogeneous in their interfaces and reports as well as their runtime requirements, and installing several tools is time-consuming. In this paper, we present SmartBugs 2.0, a modular execution framework. It provides a uniform interface to 19 tools aimed at smart contract analysis and accepts both Solidity source code and EVM bytecode as input. After describing its architecture, we highlight the features of the framework. We evaluate the framework via its reception by the community and illustrate its scalability by describing its role in a study involving 3.25 million analyses.

Haiyang Liu, Yuqi Fan, Lin Feng, Zhenchun Wei

The immutable and trustable characteristics of blockchain enable smart contracts to be applied in various fields. Unfortunately, smart contracts are subject to various vulnerabilities, which are frequently exploited by attackers, causing financial damage to users.In this paper, we study the problem of vulnerable smart contract function locating. We construct a novel Multi-Relational Nested contract Graph (MRNG) to better characterize the rich syntactic and semantic information in the smart contract code, including the relationships between data and instructions. An MRNG represents a smart contract, where each node represents a function in the smart contract and each edge describes the calling relationship between the functions. In addition, we create a Multi-Relational Function Graph (MRFG) for each function, which characterizes the corresponding function code. That is, each function is characterized as an MRFG, which corresponds to a node in the MRNG. Each MRFG uses different types of edges to represent the different control and data relationships between nodes within a function. We also propose a Multi-Relational Nested Graph Convolutional Network (MRN-GCN) to process the MRNG. MRN-GCN first extracts and aggregates features from each MRFG, using the edge-enhanced graph convolution network and self-attention mechanism. The extracted feature vector is then assigned to the corresponding node in the MRNG to obtain a new Featured Contract Graph (FCG) for the smart contract. Graph convolution is used to further extract features from the FCG. Finally, a feed forward network with a Sigmoid function is used to locate the vulnerable functions. Experimental results on the real-world smart contract datasets show that model MRN-GCN can effectively improve the accuracy, precision, recall and F1-score performance of vulnerable smart contract function locating.