Research And Implementation Of NGAP Protocal Security Flaw Detection Technology For 5G Core Network

As the current mobile communication technology develops in a rapid way,the 5G networks have been widely deployed and applied in China and abroad.With the widespread application of 5G networks,the 5G security has been followed by increasing concern.In the past two years,more and more security problems arising from or in connection with the 5G protocols have been discovered,and these security problems have different degrees of security threats to the whole application scenario and to ordinary users.The 5G core network is one of the important components of 5G network,and the security of core network communication protocol implementation will directly determine the security of the whole 5G network,so that this paper will study the NGAP protocol security flaws detection technology of 5G core network.The main research contents of this paper are as follows:(1)For the low sample efficiency of traditional fuzzy testing techniques,this paper proposes a sample efficient generation strategy,formulates a sample generation strategy based on the standard protocol format and protocol implementation details,and dynamically updates the rule base based on variant sample characteristics and target entity feedback.For the shortcomings of the traditional fuzzy testing in which the random variants lead to extremely low sample efficiency,this paper proposes a selection variation strategy based on the generation of effective samples,make the efficient selection of the field variation by using the selection variation fuzzy testing technique based on the field weight tables,and reduces the costs and expenses on the invalid sample by alternatively using the rule base variation sample filtering techniques.For the problem that the traditional fuzzy testing algorithm has high coarse granularity and cannot feedback effective sample features,this paper proposes a high fine-grained variation strategy,through which the traditional string and field variation is fine-grained to byte and bit level on the one hand,to improve the accuracy of sample variation;on the other hand,to better record the sample features that generate abnormalities,and use the effective sample features as seeds for the variation of other samples,which can easily find more of security issues.In order to address the shortcomings of traditional fuzzy testing techniques that fail to consider the protocol state transfer,this paper proposes a protocol state full traversal strategy that intelligently traverses all states of the protocol,thus improving the code coverage of fuzzy testing and thus being able to uncover more potential protocol security defects.(2)Combining the four strategies mentioned above,the paper designs and implements a NGAP protocol security flaw detection system of the 5G core network of which includes sample generation module,variant module,variant sample filtering module,communication module,monitoring module,logging module,and information feedback module,state transition module,pile insertion analysis module,dynamic update module.(3)Finally,the NGAP protocol was tested in the Free5GC environment,and some potential security flaws of the NGAP protocol were found during the testing process,while the experimental data of the optimization strategy proposed in this paper and the traditional strategy were counted and analyzed.The experimental results show that the NGAP protocol security flaw detection system implemented by combining the strategies proposed in this paper is more efficient and comprehensive in the practical testing.