Research Of Security Of Network Printer

With modern office environment showing a high degree of networking trends, office devices become independent network nodes which can access the network directly without relying on the sharing function of host computers. Remote monitoring and centralized management of office devices through network by software reduces the operating and maintenance costs effectively and improves work efficiency.At the same time, network access characteristics of the network office devices may also lead to leak of sensitive information and confidential documents. For many reasons, such as the limitation of processing capacity of embedded devices, traditional security policies are not fully applicable on network office devices, and therefore it's significant for the security of network office environment to do research on the security of network office devices.This dissertation introduces the architecture of network printers, description method of network print job page contents, the control of network printers and a series of network transmission network protocols that network print jobs involved in, based on which the workflow of network printers is analyzed in depth.Then the dissertation analyses and studies the confidentiality of the network print job progressively from aspects of security of data transmission, extracting meta data and page information from PJL control instruction stream, and restoring of page contents, and finds a serious security risk that may lead to leakage of meta data and page contents of network print jobs. Based on the result of the analyze, starting from obtaining data of network print job, this dissertation finds a method to control network printers bypassing the drivers of the system by constructing PJL control instruction stream and sending them to target network printers,which proves a serious security risk in controllability of network printers.At last, in order to demonstrate identified security risks in network print jobs, three experiments of capturing of network print job, illegal network broadcasting of network print job and remote controlling of network printer were designed to prove the serious security risks of confidentiality, integrity and controllability.