Research Of Covert Channel On Bullet Screen

Network covert channel is a secret communication channel lurking under network communication.It uses normal communication to disguise the real communication information to prevent the communication content from being peeped by others,or it is used to bypass the security policy of the security system and illegally disclose information.Since the covert channel was defined by Lampson in 1973,covert channel has developed many types and extended to many fields,becoming a technology involving many fields.At the same time,the analysis technology of the hidden channel is also developing,four aspects of the hidden channel analysis and the two basic methods of the hidden channel are given.Covert channel implementation technology and analysis technology are like prisoners and caretaker in the "prisoner model" of covert channel.They compete for development.If there is a new covert channel,t here will be a new detection technology.There will be no covert channels that can't be detected,only covert channels that cannot be detected temporarily.This paper studies a new covert channel,which is based on a brand new carrier-"barrage".Barrage is one of the most common multimedia information in video websites,and with the rise of live broadcasts and short videos,barrage will become more and more common in our lives and occupy a part of network traffic that cannot be ignored.The attributes and text contained in the barrage are good carriers for covert channels.The secret mesage is included in the application layer protocol,and it is difficult for the firewall to detect its contents in depth.And most of video websites will only filter repetitive and meaningless barrage,and barrage with some properties beyond the specified range,so the barrage covert channel has a natural covert advantage.This paper proposes a hybrid covert channel based on barrage.In addition to using covert as covert carrier,it also uses a covert channel based on tcpkeepalive to implement the control mechanism.The following will introduce the pure barrage concealed channel,mixed barrage concealed channel,covert channel demo and experimental results in turn.