# Addressing ZSM Security Issues with Blockchain Technology
## 3 The ZSM Framework Overview: Architecture and Open Security Issues
### Open Security Issues  
Among the requirements defined in [34], there are certain open security issues that are extremely vital for the ZSM's operation. The main issues and security risks of the ZSM framework as defined in [21], are as follows (and are also tabulated in Table 1):  
* The trust relationship between multiple management domains: As new NPs form their management domain and embrace the ZSM concept, the collaboration among different domains in an automated manner requires a level of trust. Their proper operation is based on a service level agreement (SLA) signed among NPs (NP1 and NP2 in the example provided above), which must facilitate the proper network conditions for the desired operation of E2E service. * Security risks introduced by the vulnerability of management function and security assurance of ZSM management function: Since the core functionality of ZSM is based on management services, the possibility of a security threat breach in the operation of those functions would be catastrophic. Therefore, the immutability and the high-security level of management functions are extremely important in ZSM networks. * Security isolation and security requirement fulfillment in a multi-tenancy environment of ZSM framework: The multitenant nature of ZSM networks should not affect the security of services supported by virtualized resources. The isolation feature inherited by the virtualization technology that is used in modern networks increases the security level which should be high in every tenant of the network. * Access control for management service provided by multiple domain service producers of ZSM framework: taking into consideration that numerous NPs provide a management service, the access over this service should be controlled and supervised in order to identify any malicious activity and avoid service malfunction. The normal functionality of these services should be safeguarded since they are the heart of the ZSM framework. * Leverage existing security specifications to identify security risks of AI/ML models and protect AI/ML models in the ZSM framework: Although AI/ML are key technologies of the ZSM and increase the automation level of modern networks by introducing characteristics such as self-adaptation and self-optimization, their susceptibility in malicious attacks is a major issue. Models used in these technologies are trained using data sets that might be tampered. This type of attack is called dataset poisoning and may lead to wrong AI/ML decisions which are major threats to the framework's proper functionality [35]. In [21], the standardization team proposes countermeasures to overcome the security issues mentioned above. Regarding the trust relationship among entities, they propose a reflective and adaptive trust model to build mutual trust among entities in the ZSM framework. The goal of this process is to ensure the confidentiality, integrity, availability, and regulatory compliance of every MD. To accomplish this, each entity that owns an MD needs to evaluate the trustworthiness of the other entity also owning an MD, based on threat and risk analysis and by examining the security policies applied in the entity. The outcome of this process leads to the building of a trust relationship among entities, followed by authentication procedures between parties and the formation of a secure channel where the behavior of each entity is tracked. Although this solution seems to tackle the trust problem, other approaches can also be investigated. The safeguarding of management functions which are crucial for the operation of ZSM is addressed using the GSMA Network Equipment Security Assurance Scheme (NESAS). This methodology defines security requirements and performs an assessment for secure product development and product lifecycle processes, using 3 GPP's defined security processes for the evaluation of network equipment.