An artificial intelligence membrane to detect network intrusion

We propose an artificial intelligence membrane to detect network intrusion, which is analogous to a biological membrane that prevents viruses from entering cells. This artificial membrane is designed to monitor incoming packets and to prevent a malicious program code (e.g., a shellcode) from breaking into a stack or heap in a memory. While monitoring incoming TCP packets, the artificial membrane constructs a TCP segment of incoming packets, and derives the byte frequency of the TCP segment (from 0 to 255 bytes) as well as the entropy and size of the segment. These features of the segment can be classified by a data-mining technique such as a decision tree or neural network. If the data-mining method finds a suspicious byte sequence, the sequence is emulated to ensure that it is just a shellcode. If the byte sequence is a shellcode, the sequence is dropped. At the same time, an alert is communicated to the system administrator. Our experiments examined seven data-mining methods for normal and malicious network traffic. The malicious traffic included 114 shellcodes, provided by the Metasploit framework, and including 10 types of metamorphic or polymorphic shellcodes. In addition, real network traffic involving shellcodes was examined. We found that a random forest method outperformed all the other datamining methods and had a very high detection accuracy, including a true-positive rate of 99.6% and a false-positive rate of 0.4%.