基于FTP目录编码的隐蔽信道

Covert channels of FTP protocol based on encoding directory

通过对文件传输协议(file transfer protocol,FTP)的研究,提出一种FTP协议信息隐藏方法。通过将特定目录编码,将秘密信息嵌入正常的更改工作目录命令(change working directory,CWD)实现隐蔽通信。对比已有的几种FTP隐蔽信道,对其隐蔽性、鲁棒性和容量进行分析,该隐蔽信道在隐蔽性和鲁棒性相同的情况下,通过适当编码大幅提高单条命令的隐藏容量,在编码数目大于一定值时,隐藏容量将高于目前已有的几种FTP隐蔽信道。实验结果验证了该方法的可行性。

A covert channels of FTP protocol was raised by studying FTP protocol to construct the FTP convert channel.Secret data were hided in the normal CWD command by encoding the specific directory.Compared with the existing several FTP covert channels by analyzing three characters including sneakiness,robustness and bandwidth.The bandwidth of single command is sharply increased by appropriate encoding,and the proposed covert channels keep the same sneakiness and robustness.When the number of encoding is greater than a certain value,the bandwidth is higher than some of the existing FTP covert channel.An experiment is presented to verify the feasibility of the method.