Abstract
Security and protection of the data is the core objective of every organization, but since cyber-attacks got more advanced than ever before, the data is compromised more often, resulting in financial loss, life loss, or privacy breaches as its consequences. There must be a system that can deal with the increasing number of cyber-attacks in flight operations, which are increasing in numbers and sophistication. Since we know that the traditional intrusion detection system is not capable enough to protect the data and as many human lives are at stake in flight operations, an unfortunate data corruption attack could give rise to a catastrophe. In this paper, we proposed a blockchain-based intrusion detection system for flight operations framework to protect the data’s privacy and avoid data corruption in flight operations. Blockchain not only protects data from corruption but also circumvents the challenges faced by intrusion detection systems which include trust and consensus building between different nodes in a network that can enhance the capability of the intrusion detection system.
Introduction
The flight operations system is responsible for the 3E’s in flight management, which are Efficiency, Efficacy and Effectiveness. Communication and coordination between the ground and travel crew are also carried out through the flight operations system. One of the significant concerns of flight operations system is providing customer safety and security and protecting their data. The struggle to protect consumer data has been going on for years and new systems are being developed for the same purpose. As the system contains critical data about the flight and the customers, any vulnerability in the system can lead to severe and fatal consequences. Therefore, the system must be equipped with susceptible security measures like intrusion detection, firewalls and attack prevention systems to secure the data and life of the customers. Several studies and models have been presented in the past that give rise to new advancements in the security system of flight operations system. The advancement in technology is growing at a tremendous rate. It is expected to grow further in the future, with multi-agent systems installed in flight operations systems to handle tasks that were once impossible for humans.
In this paper, the proposed agent-based flight operations system keeps the redundant data task and communication flowing throughout the system without interruption. Multi-agent systems are used to collaborate, negotiate and coordinate with different agents to solve system problems because cooperation between multiple agents is necessary to deal with large data sets and system challenges [1, 2]. However, in flight operations system, humans can’t handle such massive data. Therefore a system needs to be designed with multi-agent systems without affecting the performance [3]. In this study, we demonstrate the application of blockchain technology in intrusion detection systems to overcome the insufficiency of traditional Intrusion Detection Systems (IDS) to detect attacks efficiently. It also provides a decentralized nature to our flight operations system. The essential aspects of the flight operations system considered in every flight operation model can be categorized as air resources, ground resources and maintenance.
Cyber-attacks are the breach of the system with malicious and ulterior motives to damage the data and to steal it [4]. There are different types of attacks that can be executed on flight operations system including Man-in-the-middle (MITM) attack, Data Injection attack, Spoofing attack, Denial of Services attack and Insider threat. There are different types of methods that we can use to prevent these attacks like using encrypted algorithms, use of IDS, special keys update, traffic analysis surveys, security awareness programs
The flight operations system has used Security Management Systems (SEMS) to deal with these attacks. But despite all efforts, many attacks have been successful and a lot of data has been stolen over the past few years [5, 6, 7]. Some attacks are IT operator SITA – 2021, Easyjet – 2020, Cathy Pacific Airways – 2018, British Airways – 2018 and Air Canada – 2018. The most common types of IDS are network-based, host-based protocol-based IDS, namely NIDS, HIDS and PIDS. A NIDS monitors the network and detects any unusual activity or unwanted traffic entering the system. It is mostly added at the entrance point of the system where the data comes in through the network so that the intrusion can be detected at the ear. A HIDS detects and monitors the systems’ internals for abnormalities and unusual behavior. This type of IDS is installed to check the system from the inside. It is used when for an unknown reason, the attacker manages to trespass the firewalls of the system and is not detected by the NIDS. A PIDS monitors the protocols that are followed by the system to send messages. This type of IDS is also installed at the far end of the system to verify the proposals as soon as it enters the system [8].
There are two types of IDS methods that use two different techniques for dealing with intrusions. These include Signature-based methods that works on the principle of pattern creation. As it encounters any attack, it creates a signature of that attack depending upon the indicators of compromise and stores them in the system’s database for future reference. The second method is called Anomaly-based that works by developing an ideal condition model of our system and store that in the database. Upon detection of the attack, it directly matches the system’s condition with that of the model stored in the database and acts accordingly [9].
Flight operation systems are critically sensitive as they involve a human life at risk or the safety and secrecy of personal data. flight operations system has been using SEMS [10] in the past, which despite all functionalities of data protection, couldn’t resist the attacks which resulted in money and data corruption. Our objective is to prevent all attacks from happening without affecting system performance. What technology can provide adequate data security and how to integrate that technology into the flight operations system? To deal with this situation, we have used an IDS that works together with blockchain to detect cyber-attacks and protect data and its integrity.
Literature review
Previously, none of the approaches has used blockchain for intrusion detection in flight operation systems. [11] talks about the security of cryptocurrencies and how blockchain technology ensures their data integrity and secrecy. It talks about the emergence of blockchain and, through different systematic examinations, checks its robustness and credibility to stand against different possibilities of data invasion. [12] focusses on online payment transactions through a digital signature to provide extra security to the owner but despite all the work, the problem of double-spending without the intervention of the third party could not be solved. blockchain timestamps the transactions, thus solving the problem. [13] have used a social approach making the agents’ actions an obligation to solve the problem of agents having limited resources or a higher degree of dependability.
In [20] the problem of false alarms with IDS has been taken care of through the use of the verification method of the blockchain and also prevents the outflow problem of information to a third party. [21] uses the signature method for recording information about the attacks in the form of patterns of 0 s and 1 s. [22] the uses signature-based IDS method for recording information about the attacks. A Signature-based method works on the principle of storing patterns of the attacks in the form of 0 s and 1 s and storing them for future reference. [23] proposes a blockchain anomaly detection to eliminate the single point of failure in a system. It uses blockchain meta-data to control malicious activities and thus prevent them. The distributed nature also helps in avoiding any failure of the system. [24] uses IDS for vehicular networks against threats on the network. As a large number of data is exchanged between carrier and network, it needs to be protected from cyber-attacks, for this it uses distributed algorithm-based IDS. [25] introduces Selp-adaptive Multi-Agent Real-Time Systems (SMARTS) to enable real-time decisions and self-adaptation in the agents as systems are becoming complex and resources were being drained because of no proper method present to cope with the situation. The TAPAAL model checker is used for the verification of the model and it showed promising steps to enhance the decision of the system. In [26], the centralized system for UAVs has been replaced with a decentralized one as the earlier one was susceptible to many cyber-attacks. This new decentralized approach uses a machine learning framework with blockchain to enable the system to take a rational decision without any alien intervention. In [27] applications of blockchain have been discussed like smart contracts, bitcoin, the internet of things (IoT), smart grids, cybersecurity, etc. along with blockchain’s functions including hash-chained databases, mixing protocols, anonymous signatures, consensus algorithms, etc. In [28] the decentralized power of the blockchain in the field of healthcare, insurance, real estate and the voting system has been discussed. It also demonstrates how the use of blockchain could revolutionize these fields in the future and could help protect them from attacks like Eclipse attacks, selfish mining attacks, liveness attacks, etc. [29] describes CIDS as a promising offering for the identification of collective and coordinated cyber-attacks. CIDS despite all the advantages over the traditional one, faces huge problems in coordination with every IDSs in the system. Blockchain builds consensus and compliments CIDS for better performance. In [30], an architecture for signature-based IDS that solves problems like exchanging information without the hesitation of data loss or manipulation is used. It also resolves trust issues as blockchain is a trustless technology. A study [31] proposed a collaborative model using Federated Learning for passenger demand forecasting in smart city transportation to protect user privacy by enabling autonomous taxis to improve their demand forecasting models without sharing passenger data directly. A study [32] introduced an agent-based security risk management approach that includes risk assessment, scope selection, agent-based model and risk mitigation. These four steps use Monte Carlo simulation to perform better. [33] strengthens the defense of IDS using Blockchain-enabled collaboration with intrusion detection. Blockchain along with SDN benefits each other to create an intrusion-free system achieving security-related objectives. In [34], security, multi-agent systems, blockchain and deep learning algorithms have been discussed. These work together to enhance the environment, protect the system from intrusion and secure the data.
However, none of these approaches have used blockchain for efficient intrusion detection in agent-driven flight operations. The majority of the work either focuses on forming trust between different components of an intrusion detection system through consensus protocol or eliminating false alarms in intrusion detection through blockchain verification. What if we want an autonomous entity to handle all the intrusion-related activities like its detection and secure storage for the future? How can we ensure that our attack signatures, including signature and anomaly-based, will themselves be kept safe from an attack? How can we ensure that multiple agents can develop trust in each other while working in a multi-agent system? This is where our proposed approach becomes useful. Blockchain can provide a reliable audit trail for incident investigations by ensuring that logs are immutable and tamper-proof. Additionally, blockchain-based consensus mechanisms can facilitate real-time anomaly detection by enabling multiple nodes to validate and cross-check data, thereby reducing the risk of false positives and enhancing the robustness of the IDS.
Proposed blockchain-based intrusion detection system for flight operations framework
The proposed Blockchain-based Intrusion Detection System for Flight Operations (BIDFO) framework is presented in Fig. 1. It combines blockchain with an IDS to secure the data and information of flight operations and a few other components to record data and communicate it throughout the network. There are two types of nodes in this network the control room and the aircraft. Messages from all the nodes are generated through a data-transmitting component and then communicated into the network through a communication module. The data thus transmitted is sent to the proposal generation component, which decides the authenticity of the data and generates an alarm if any abnormal behavior is found.
The next component of our framework is the CIDS component which includes a consensus module, incentive module and blockchain. Once the data is entered into the blockchain, it cannot be changed or altered. The consensus module ensures that there is no different copy of the blockchain as its distributed through the network.
Data transmission
The nodes aircraft and the control room transmit the data into the network through this module. The data-transmitting component is designed to enable communication between these two nodes. This component includes the agents that take care of the data and messages transmitted through the communication module.
Data generation
This module is responsible for data generation and messages. The quality and authenticity of the data are controlled in this module. The data generated by the control room is mainly about navigation, warnings, vertical positions, etc., while the information provided by the aircraft is controller information, engine health, etc.
The proposed blockchain-based intrusion detection system for flight operations (BIDFO) framework.
Messages generated by the transmission component are then transmitted to other framework components through the communication module. This module is responsible for starting the conversation and also receives messages from other components and nodes.
Warning generation
It generates warning alerts and depending on the data received from the Data Transmission Component, it finds out that the data coming into the system does not follow the protocols, addresses, semantics, etc. Therefore, the input given to this component is deemed as a proposal for this component. It contains two types of patterns that are triggered and periodic.
Triggered pattern
This pattern works if an unusual behavior or data is entered into the system through any node. It consists of a whitelist of all the addresses like IP, MAC and ports and also of protocols used by the proposed system. If the addresses and protocols do not match with that whitelist, it generates an alert.
Periodic pattern
Some attacks do not trigger this component and can silently trespass into the system and the data could be stored in the blockchain as genuine and authentic data. A periodic pattern is used to deal with these types of attacks as it regularly checks the system for any abnormality. If
The working of the proposal & warning generation component is demonstrated in Algorithm 1.
Intrusion detection system methods with independent detection
The flight operations system is a complex system and contains many data dependencies. The independent detection ensures the data is being shared with proper syntax and the exact same semantics specified in the system. We use signature and anomaly-based methods IDS in the proposed framework that complement each other through their functionalities, as shown in Fig. 2.
Integration of intrusion detection system methods with blockchain.
Recording nodes and detector nodes.
It contains the consensus algorithm initially to keep the blockchain neutral. The following module is the incentive mechanism that rewards and punishes the network’s miners. And lastly, the data is stored inside the blockchain permanently.
Consensus creation
It builds consensus and keeps it between every node of the network. As blockchain is distributed all over the network, keeping it the same at each node is necessary. Furthermore, as there is no central authority in the blockchain and each node can act arbitrarily, it is essential to build consensus to maintain the blockchain and the decentralized nature of this technology.
Suppose a situation exists in which two different copies of the blockchain are found. Then, the consensus is run to decide between both copies of the blockchain and selection will depend upon the number of copies against every node in the network. A different copy of the blockchain is created when one of the nodes rejects a valid and authentic block and does not add it to its copy of the blockchain, thus creating an orphan chain. The node currently adding the block to the blockchain is called the recording node, while all the other nodes are called the detecting nodes. The detecting nodes can accept and reject the newly created block. Figure 3 shows both recording and detecting nodes. The block is dismissed by one of the detecting nodes and received by most other detecting nodes.
In Fig. 3 only one node has rejected the copy of the recording node and that particular node would not make this specific block part of the blockchain, thus making its copy the orphan copy of the blockchain. As soon as an orphan chain is created in the blockchain, a consensus algorithm runs and the orphan chain formed previously gets rejected. Figure 4 shows a copy B5 being rejected as it has become an orphan chain and every other copy contains the same copy.
Blockchain network with orphan chain.
In the proposed model, we implemented blockchain instead of a traditional database because blockchain provides security and secrecy. The process is shown in Fig. 5. It presents how a block is added to the blockchain and what steps are necessary for a successful transaction.
Steps on how a block is entered into the blockchain.
Our framework allows us to save two different types of data in it. The responsibility of blockchain in our framework is to store information about the attacks. Signature-based IDS, after encountering any cyber-attack, creates a signature of that attack in the form of patterns and stores them in the blockchain for future use. While the Anomaly-based IDS stores in the blockchain the system’s expected behavior and use that as a reference against new attacks. Script 1 shows the attributes of the class AttackInfo received via the constructor. Figure 6 shows the block containing information about the attacks.
Script 1: Class for storing attacks information 1. class AttackInfo { 2. constructor (Activities, System_Ip, irregularities, Signature) { 3. this.activities
Block containing IOC of cyber-attack.
Blockchain also stores communication between different nodes of the network. The data is critically important to protect; therefore, we have used blockchain to store them to prevent any misuse and manipulation of the data. Script 2 shows the attributes of the class AircraftInfo received via constructor. Figure 7 shows the block containing information about the control room and the aircraft.
Block containing aircraft information.
Script 2: Class for storing aircraft information 1. class AircraftInfo { 2. constructor (Air_id, velocity, height, warning_signs, control_panel, airfoils) { 3. this.Aircraft_id
Hash is a function that maps or converts the data into bits of an array of fixed length. The hash calculated for each block depends on all the block’s attributes. Miners have to calculate the nonce value until the hash comes within the targeted value selected by the system. Figure 8 shows a flowchart that explains the procedure of calculating hash.
Hash value calculator.
Implemented blockchain is divided into two main sections. The first one contains the code for creating the block, adding its information and storing the data inside that block, while the second section creates the chain between these blocks created in section one and thus forms the blockchain. The coding is done using Node.js language and Visual Studio code is used for compilation. Script 3 shows the code of a single block that will be added in a blockchain. Script 4 shows the code for complete blockchain.
Script 3: Class for storing aircraft information 1. class SingleBlock { 2. constructor (blockData) { 3. if (blockData
Script 4: Class for complete blockchain 1. class OurBlockchain { 2. constructor () { 3. id
Representation of blockchain.
The code demonstrated above creates a fully functional blockchain with each block connected to the surrounding blocks with the help of their hash values. A slight change in the data would change the hash value altogether and the connection between these blocks would break. Figure 9 shows a complete consolidated view of the blockchain containing actual data of the flight operations system.
We considered a flight operation in Fig. 10. To check the robustness and credibility of our BIDFO framework against a challenging scenario containing control rooms, aircraft, an antenna and other communications like Air-to-Air, Ground-to-Ground and Air-to-Ground, communications like Air-to-Air, Ground-to-Ground and Air-to-Ground, denoting communication between the aircraft, control rooms and aircraft to control room respectively.
Flight operations system.
We will use the flight operations which has been discussed in Fig. 10. It consists of two control rooms and let’s suppose that the attacker blocks the communication of ground with any of the aircraft and sends his data by taking control of one any control room. The attacker now has the chance to manipulate and change the aircraft’s communication, misleading the aircraft for any ulterior motive. The attacker can now change the blockchain’s data or add a new block of data. The black arrows in Fig. 11 clearly show the path attacker can travel or have access to. The attacker can affect every node connected through the blockchain as the same copy of the blockchain is distributed to each node. The attacker now has illegal and unauthorized access to our flight operations and can damage the aircraft’s data.
Flight operations system attacked by an unauthorized person.
The scenario depicts that an attacker entered the system through the network. It has an ulterior motive of hijacking an aircraft A1 by changing its landing location. The attacker does this by adding a new block containing the data of aircraft A1 in the blockchain. Now, as the attacker gets all the access, it transmits data into the blockchain which first passes through the IDS. Figure 12 demonstrates an attempt to add the data through IDS.
The data sent by the attacker is passed through the IDS, which checks its source for any abnormalities. If the source does not match that of the sources present in the whitelist, the IDS generates an alert and appends that alert with the block’s data. The figure demonstrates how a warning message is appended to the data.
Steps of how block enters into the blockchain.
After the data is passed with a warning attached, it becomes part of the attacker’s copy of the blockchain. Figure 13 shows three copies of the blockchain that denotes a grey-colored block as the attacker’s block, which has not yet become part of other nodes. A block must be verified by miners and can be part of every other copy of the blockchain.
Newly entered block which is not yet become part of the blockchain.
When miners are presented with a block for validation, they check for any warning messages with the original data before calculating the has via Proof of Work (PoW). In case any miner receives any notice, it rejects the block and does not initiate PoW for that particular block. The miner’s procedure is shown in Fig. 14.
Operation of verification by a miner.
As the miner rejects the block and none of the detecting nodes agree to make the rejected node part of the blockchain, the specified block is rejected and removed from the attacker’s copy of the blockchain. Figure 15 shows the scenario when an intruder try to add a block in blockchain without the consensus of others. Figure 16 presents the rejection of block by miners.
Intruder trying to add a block 4.
Rejection of block added by an unauthorized person.
The above scenario proves how blockchain can save data from manipulation and alteration. In addition, the scenario demonstrates two significant pros of using blockchain: verifying the data before entering and ensuring that the data must follow the semantics and protocols set by the organization.
The above scenario indicates that blockchain technology is taking over any traditional data storage and transmission system as it provides many features beyond just data storage, including data retrieval, data security, consensus building in case of conflict and decentralization of powers and authorities. Therefore, we can now compare a traditional system with databases or IDSs without Blockchain so that it can prove why blockchain is emerging as a path toward web 3.0.
From the above scenario, if any intruder sends its data into the blockchain, it will be rejected by the miners during the verification method. However, if this attack is carried out on a system without blockchain, all data and information will be lost and the attacker will succeed in his nefarious purposes. Miners calculate a hash, perform PoW and verify the authenticity and rightness of the data being sent into the system from its nodes. As blockchain is distributed throughout the network, if any of the blockchain data is manipulated or damaged, it will be impossible for an attacker to change it across all nodes and copies of the blockchain due to a concept called PoW. The PoW algorithm delays the time to recalculate hash values of each block, whereas there is no such concept in traditional database. Figure 17 compares the time required to manipulate the data in the blockchain and the traditional database.
Time required recalculating hash of a single block after data manipulation.
The graph above shows that it would take around 32 minutes for four nodes to be manipulated, while only three minutes in any database. Figure 18 shows the combined time needed by the attacker to alter the data of four nodes.
Comparison of flight operation system with and without blockchain
Time to recalculate Proof of Work (PoW) for every node.
The graph presented above clearly shows that the time needed for data manipulation in all the copies is exponentially larger than the required time in a Blockchain-less system. The total time for all four nodes would be more than 100 minutes, even larger than a single node. The time mentioned here is for just four nodes; each had four blocks in its blockchain, which is impractical in a fully working flight operations system. The greater the number of blocks in a Blockchain and nodes in the network, the more time would be required by the attacker to calculate the hash value for each block, thus taking thousands of minutes to do so and even computers with huge computational capabilities could not calculate it in less time than that. The other algorithm like Proof of Stake (PoS) helps to maintain the integrity of the blockchain through proper consensus-building capabilities. Data recovery is also one of the most important benefits that come with using blockchain, as it is distributed in nature and a system failure at any node does not bring down the entire blockchain, rather any node can request a copy of the blockchain from another node.
Table 1 shows the comparison between a blockchain-based and a blockchain-less system. It indicates that blockchain wins in all conditions and aspects of the flight operations system.
Blockchain and Collaborative IDS are the two main highlights of this research. IDS provides the necessities to the framework as detecting intruders and recording their patterns into the system for future use. Blockchain deals with the challenges such as building consensus, providing a trustless environment and protecting the data of both the IDS and the communicating nodes. Other benefits that one may get include immutability, add-only behavior, key-protected, etc. All these blockchain functionalities defy any catastrophe event from happening in flight operations system. Our blockchain based intrusion detection for flight operations (BIDFO) framework enables communication of the data between all the nodes connected in the network while detecting unwanted intrusions into the system. Our IDS system in the framework is trained to detect these intrusions through signature-based and anomaly-based methods, thus strengthening the flight operations system from every perspective.
In the future, the proposed model can be integrated with various consensus algorithms such as Delegated Proof of Stake (DPoS), Proof of Activity (PoA), Raft and Practical Byzantine Fault Tolerance (PBFT) to test the capabilities of our BIDFO framework and how these algorithms help in improving and enhance the framework. Furthermore, our framework can also be used as a risk estimation system with some alterations and modifications.
Footnotes
Author’s Bios
