1. [2022CISCN]ez_usb:键盘提取压缩包和密码流量分析

首先题目给的提示是这个是键盘流量，那么我们搜索8个字节长度的数据包，这里发现有两个Destination的数据包的长度是8，说明键盘给两个地方输入了值

tshark分别提取出压缩包和压缩密码

tshark -r ./ez_usb.pcapng -Y 'usb.data_len == 8' -Y 'usb.src =="2.8.1"' -T fields -e usb.capdata > 1.txt
tshark -r ./ez_usb.pcapng -Y 'usb.data_len == 8' -Y 'usb.src =="2.10.1"' -T fields -e usb.capdata > 2.txt

再利用脚本

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>"}


def out(file):
    keys=open(file)
    output = []
    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))
    print()
    
out("1.txt")
out("2.txt")

得到output：

526172211a0700<CAP>c<CAP>f907300000d00000000000000c4527424943500300000002<CAP>a000000<CAP>02b9f9b0530778b5541d33080020000000666c61672<CAP>e<CAP>747874<CAP>b9b<CAP>a013242f3a<CAP>fc<CAP>000b092c229d6e994167c05<CAP>a7<CAP>8708b271f<CAP>fc<CAP>042ae3d251e65536<CAP>f9a<CAP>da87c77406b67d0<CAP>e6316684766<CAP>a86e844d<CAP>c81aa2<CAP>c72c71348d10c4<CAP>c<DEL>3d7b<CAP>00400700
output :        526172211a0700Cf907300000d00000000000000c4527424943500300000002A00000002b9f9b0530778b5541d33080020000000666c61672E747874B9Ba013242f3aFC000b092c229d6e994167c05A78708b271fFC042ae3d251e65536F9Ada87c77406b67d0E6316684766a86e844dC81AA2c72c71348d10c43D7B00400700

35c535765e50074a
output :35c535765e50074a

然后用Notepad++打开转ASCII保存，再用rar打开，输入密码即可拿到flag