USB流量分析

USB接口是目前最为通用的外设接口之一，通过监听该接口的流量，可以得到很多有意思的东西，例如键盘击键，鼠标移动与点击，存储设备的明文传输通信、USB无线网卡网络传输内容等。

1、USB流量的捕获

USB流量的捕获可以使用wireshark自带的工具usbpcap来进行

安装wirshark时勾选上安装usbpcap即可

1.鼠标流量

抓包

鼠标移动的轨迹，右键，左键的行为都能捕捉到

(这里有个坑，有的鼠标可能协议不标准、抓到的数据分析不了)

保存为pacp文件

USB协议的数据部分在Leftover Capture Data域之中，在Linux下可以用tshark命令可以将 leftover capture data单独提取出来命令如下：

tshark -r 7777.pcapng -T fields -e usb.capdata > usbdata.txt

运行命令并查看usbdata.txt 发现数据包长度为八个字节

写出解密脚本

nums = []

keys = open('usb.txt','r')

posx = 0

posy = 0

for line in keys:

    if len(line) != 12 :

         continue

    x = int(line[3:5],16)

    y = int(line[6:8],16)

    if x > 127 :

        x -= 256

    if y > 127 :

        y -= 256

    posx += x

    posy += y

    btn_flag = int(line[0:2],16)  # 1 for left , 2 for right , 0 for nothing

    if btn_flag == 1 :

        print posx , posy

keys.close()

当btn_flag 取1时对应鼠标左键、2对应鼠标右键

运行脚本可以得到一系列坐标点

得到这些点之后，需要将他们画出来，因而需要辅以gnuplot 或者其他的绘图工具，gnuplot的命令为"plot inputfile"，运行如下：

使用一航大佬的工具

键盘流量

一样的抓包方式

确定为键盘流量后

tshark -r 1111.pcapng -T fields -e usb.capdata > usbdata.txt

脚本

#!/usr/bin/env python

# -*- coding:utf-8 -*-

normalKeys = {"04":"a", "05":"b", "06":"c", "07":"d", "08":"e", "09":"f", "0a":"g", "0b":"h", "0c":"i", "0d":"j", "0e":"k", "0f":"l", "10":"m", "11":"n", "12":"o", "13":"p", "14":"q", "15":"r", "16":"s", "17":"t", "18":"u", "19":"v", "1a":"w", "1b":"x", "1c":"y", "1d":"z","1e":"1", "1f":"2", "20":"3", "21":"4", "22":"5", "23":"6","24":"7","25":"8","26":"9","27":"0","28":"<RET>","29":"<ESC>","2a":"<DEL>", "2b":"\t","2c":"<SPACE>","2d":"-","2e":"=","2f":"[","30":"]","31":"\\","32":"<NON>","33":";","34":"'","35":"<GA>","36":",","37":".","38":"/","39":"<CAP>","3a":"<F1>","3b":"<F2>", "3c":"<F3>","3d":"<F4>","3e":"<F5>","3f":"<F6>","40":"<F7>","41":"<F8>","42":"<F9>","43":"<F10>","44":"<F11>","45":"<F12>"}

shiftKeys = {"04":"A", "05":"B", "06":"C", "07":"D", "08":"E", "09":"F", "0a":"G", "0b":"H", "0c":"I", "0d":"J", "0e":"K", "0f":"L", "10":"M", "11":"N", "12":"O", "13":"P", "14":"Q", "15":"R", "16":"S", "17":"T", "18":"U", "19":"V", "1a":"W", "1b":"X", "1c":"Y", "1d":"Z","1e":"!", "1f":"@", "20":"#", "21":"$", "22":"%", "23":"^","24":"&","25":"*","26":"(","27":")","28":"<RET>","29":"<ESC>","2a":"<DEL>", "2b":"\t","2c":"<SPACE>","2d":"_","2e":"+","2f":"{","30":"}","31":"|","32":"<NON>","33":"\"","34":":","35":"<GA>","36":"<","37":">","38":"?","39":"<CAP>","3a":"<F1>","3b":"<F2>", "3c":"<F3>","3d":"<F4>","3e":"<F5>","3f":"<F6>","40":"<F7>","41":"<F8>","42":"<F9>","43":"<F10>","44":"<F11>","45":"<F12>"}

output = []

keys = open('usbdata.txt')

for line in keys:

    try:

        if line[0]!='0' or (line[1]!='0' and line[1]!='2') or line[3]!='0' or line[4]!='0' or line[9]!='0' or line[10]!='0' or line[12]!='0' or line[13]!='0' or line[15]!='0' or line[16]!='0' or line[18]!='0' or line[19]!='0' or line[21]!='0' or line[22]!='0' or line[6:8]=="00":

             continue

        if line[6:8] in normalKeys.keys():

            output += [[normalKeys[line[6:8]]],[shiftKeys[line[6:8]]]][line[1]=='2']

        else:

            output += ['[unknown]']

    except:

        pass

keys.close()

flag=0

print("".join(output))

for i in range(len(output)):

    try:

        a=output.index('<DEL>')

        del output[a]

        del output[a-1]

    except:

        pass

for i in range(len(output)):

    try:

        if output[i]=="<CAP>":

            flag+=1

            output.pop(i)

            if flag==2:

                flag=0

        if flag!=0:

            output[i]=output[i].upper()

    except:

        pass

print ('output :' + "".join(output))

直接使用大佬的工具

参考链接：

https://www.jianshu.com/p/92064f2e9dcb

https://www.anquanke.com/post/id/85218

工具

 https://ctf-wiki.github.io/ctf-wiki/misc/traffic/protocols/USB/

巴特西

CTF MISC-USB流量分析出题记录

USB流量分析

1、USB流量的捕获

1.鼠标流量

键盘流量

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