# An Effective Blockchain-Based Defense Model for Organizations against Vishing Attacks
Dual control focuses more on the transactions and task completion; however, the split knowledge condition essentially focuses on the data being split between two or more persons to prevent any person from having complete knowledge (i.e., dual controlling the information). Blockchain is a mechanism for storing data in a way that makes system changes, hacking, and cheating hard or impossible. A blockchain is simply a network of computer systems that duplicates and distributes a digital record of transactions throughout the entire network. Each block on the chain comprises several transactions, and each participant's ledger receives a copy of each new transaction that takes place on the blockchain. Transactions on a blockchain are stored with an unchangeable cryptographic signature known as a hash. Distributed ledger technology (DLT) refers to a decentralized database that is governed by several users. Our proposed method is the first that uses security principles for detection and mitigation of vishing attacks (i.e., a kind of SE attack achieved through phone calls). We first categorize the SE attacks according to the security principle required to stop them. Then, this paper proposes a new practical vishing attack defense model for organizationsthat delineates the security principles to use to avoid attacks. The blockchain is a crucial solution used to ensure that decisions are taken transparently and collectively and that each transaction is trustworthy, backed up with a securely stored record [14]. It has a wide area of applications such as healthcare [15], agriculture [16], smart cities [17], etc. Blockchain is used mainly to enhance the dual control security principle by creating a new block only when all parties decide about a potential phone call and demonstrate the split knowledge principle since the victim does not have complete knowledge of any secret or sensitive information. The proposed model is for organizations and not for individuals. Thus, the word 'victim', in this paper, refers to the organization's employees targeted by the SE attacker. To summarize, the paper's contributions are:  
1. The Categorization of SE attacks based on the security principles required to avoid them. 2. The proposition of a new framework that uses blockchain networks to dual control any potential transaction through its management flow and to enable split knowledge so that the victim does not have complete information and needs to request the remaining information from other parties within the blockchain network. 3. The easy adoption and practical implementation of the proposed model within organizations, using free open blockchain platforms. The proposed framework has the following advantages:  
* Avoiding the psychological status of the recipient of the vishing calls. * Avoiding the recipient of the call having to act alone. * Helping to make the right decision about received calls. * Dual controlling critical phone calls. * Using Blockchain to ensure that decisions are made collectively and transparently. * Ensuring the accountability of any critical decision regarding phone call requests. The remainder of this paper is divided as follows. Section 2 surveys the current works dealing with defense against SE attacks and discusses their limitations. In Section 3, we propose a new categorization of SE attacks based on the defensive measures to stop them. Section 4 presents a proposed new vishing defense model that uses Blockchain techniques to implement security principles. In Section 5, we demonstrate the easy adoption of the proposed framework using a hyperledger fabric and an open and free blockchain network. In Section 6, we discuss how well the suggested model performed. Finally, we conclude the paper in Section 7.