# Blockchain for Future Wireless Networks: A Decade Survey
## 3 The Proposed Taxonomy for Security Attacks and Countermeasures
### Active Attacks  
In an active attack, the attacker modifies the message that sends from the sender to receiver. Malicious users can alter authorized data, such as source and destination address, timestamp, and user data. In addition, they can perform unauthorized transmission, modify the data to maneuver the behavior of the WN application, and block the critical resources (critical data, web server, and jamming the radio frequency) using DDoS attacks [76]; the following are examples of active attacks in WNs.  
* Masquerade attack--A malicious user behaves like an authorized person to deprive the resources of the system [77]. They can capture authentication sequences and legitimately retrieve the access privileges to the target system. This attack creates a fake network identity that affects the financial transaction systems by phishing emails [78]. Furthermore, it makes counterfeit servers and sends data-stealing malware for their own malicious usage. In [79], the author proposed a signal strength fluctuation model to perform significant testing of masquerade attacks in a mobile ad hoc network (MANET). Moreover, using a masquerade attack, a malicious user can hack and remotely control modern vehicles. For that, ref. [80] proposed an authentication protocol that protects the electronic control units. Furthermore, [PERSON] et al. [81] introduced a blockchain-based solution using renewable hash chains that resist masquerade attacks in the identity authentication approach.
* Replay attack--In this attack, an intruder intercepts the communication and captures user data, then modifies it and sends it back to the destination to misdirect him [82]. It creates duplicate transactions in-network and gains information. Secure socket layer (SSL) or transport layer security (TLS) protocols, one-time passwords, timestamp methods, and session key encryption methods are used to prevent replay attacks [83]. Multiple researchers offer various solutions to prevent replay attacks for applications, such as vehicular ad hoc networks (VANETs), mobile ad hoc networks (MANETs), and IoT networks. For that, the author of [84] analyzed the existing schemes that prevent replay attacks in VANETs. In [85], the author proposed a model that overcomes replay attack breaches in authentication conditions of a smart city. In identity authentication scheme [81], [PERSON] et al. proposed a timeout mechanism that prevents replay attacks. Apart from these, [PERSON] et al. [86] introduced shared session values and freshly random values that create different session messages, which can be used to mitigate the replay attack probability.
* Modification attack--An attacker modifies some portion of the message transmitted from sender to receiver, which results in delivering corrupted and delayed messages [82]. It affects the data integrity and re-configuring of system hardware. A malicious user performs three types of modifications, i.e., change information, insert information, and remove existing information. To prevent this attack, encryption algorithms, traffic padding, and various messaging techniques, such as authentication code, sequence numbers, and checksums, are used [87]. Many researchers work to mitigate the issue of modification attacks in WN security. For that, [88] discussed how to overcome price modification attacks in smart grid applications. In [89], [PERSON] et al. discussed a existing method that suppresses the modification of attack in VANETs. Moreover, [PERSON] et al. [90] proposed a blockchain-based message authentication code and group signature mechanism that eliminates the effect of modification attacks for smart homes systems.