Misc-机密信息(Write

题目信息

来源：2017-赛客夏令营-Misc-机密信息

难度：⭐⭐⭐⭐

平台地址：CTFHub

技术要点

后缀名更改

压缩包暴力破解

简单的Python编程

解题思路

题目附件给出一张图片，首先第一步思路，尝试扫描图片信息，查看是否可能隐藏flag

使用StegOnline对所给图片进行扫描，查看其RGBA值和字符串数值

RGBA如下（RGBA.txt）

字符串数值

可以看到，有对应的flag.txt文件隐写在图片中，因此只要找到对应的txt文件就能找到flag的下落。

同时尝试修改图片对应的文件后缀名，发现当修改到.zip格式文件打开需要密码

因此，需要对该文加进行密码破译，此处采用暴力破解,此处我使用了Ziperello进行破解

破解成功，得到密码为：7878

成功得到对应的flag.txt文件

打开对应的txt文件，分析内容

可看到对应的文件为01组成的字符串，则可以联想到最后的flag一定是通过对应的编码进行而隐藏的信息

编写python程序把01字符串转化成二维码，扫码既得对应的flag信息

python代码如下（python代码）：


from PIL import Image

MAX = 70
img = Image.new("RGB",(MAX,MAX))

str  = "0000000000000000000000000000000000000000000000000000000000000000000000"
str += "0000000000000000000000000000000000000000000000000000000000000000000000"
str += "0011111111111110110000111110000001001111110000000110000011111111111100"
str += "0011111111111110110000111110000001001111110000000110000011111111111100"
str += "0011000000000110110000001111100110111111001111111001110011000000000100"
str += "0011000000000110110000001111100110111111001111111001110011000000000100"
str += "0011001111100110111111110001100111000011110111100111110011011111100100"
str += "0011001111100110001111001000011111001111111000011111110011011111100100"
str += "0011001111100110001111001000011111001111111000011111110011011111100100"
str += "0011001111100110000011000000011001110011000111111000000011011111100100"
str += "0011001111100110000011000000011001110011000111111000000011011111100100"
str += "0011000000000110110000000110011111000011110001111111110011000000000100"
str += "0011000000000110110000000110011111000011110001111111110011000000000100"
str += "0011111111111110110011001001100110110011001001100110110011111111111100"
str += "0011111111111110110011001001100110110011001001100110110011111111111100"
str += "0000000000000000111100000110000110111100000111111000000000000000000000"
str += "0000001111100110110000001110000111110011111000000111111111100001111100"
str += "0000001111100110110000001110000111110011111000000111111111100001111100"
str += "0000110111100001110011110000000000000011000110000001001100111110011000"
str += "0000110111100001110011110000000000000011000110000001001100111110011000"
str += "0011000000000110000011111110011000110000001000011111111111100111100100"
str += "0011000000000110000011111110011000110000001000011111111111100111100100"
str += "0000000001111001000011110110011111000000001001100001001100100000000000"
str += "0000000001111001000011110110011111000000001001100001001100100000000000"
str += "0000001110011110000011110111100000110000000110011001111111111001100100"
str += "0000000001111001000011110000011000001111000000011110001100000000011000"
str += "0000000001111001000011110000011000001111000000011110001100000000011000"
str += "0011111110011110111111001001100111111111001111100001110011011111100100"
str += "0011111110011110111111001001100111111111001111100001110011011111100100"
str += "0011001000011000001100000001111111111111110001100001111111100000000100"
str += "0011001000011000001100000001111111111111110001100001111111100000000100"
str += "0011001001100111111100111110011111001100000111111111110011011111100100"
str += "0011001001100111111100111110011111001100000111111111110011011111100100"
str += "0000110110011001111111000111100001110011001001100000001100100110000000"
str += "0011001110000111110011001111100000000011110000000111111111011111111100"
str += "0011001110000111110011001111100000000011110000000111111111011111111100"
str += "0011000001100000111100000001111000111100110110000000000000100110011000"
str += "0011000001100000111100000001111000111100110110000000000000100110011000"
str += "0000001000011110111100000111111000110000000000011111110011011001111000"
str += "0000001000011110111100000111111000110000000000011111110011011001111000"
str += "0000111111111001000000111110011111001111110001100000001100100111111100"
str += "0000111111111001000000111110011111001111110001100000001100100111111100"
str += "0000111001111110110000111110000001000011000111100001111111100000011100"
str += "0011001111111001000011000001111000111111000111100111000011000000011000"
str += "0011001111111001000011000001111000111111000111100111000011000000011000"
str += "0000110000000110001100110000011110001111111000000001000011000111100000"
str += "0000110000000110001100110000011110001111111000000001000011000111100000"
str += "0011000001100001110011001110011000001100111001100111110011000110000000"
str += "0011000001100001110011001110011000001100111001100111110011000110000000"
str += "0011001000000111000011001110011110110011110000000110000000000001111100"
str += "0011001000000111000011001110011110110011110000000110000000000001111100"
str += "0011001111111001111100111111100111001111001001100110111100000110011100"
str += "0011001000011111110011110111111001001111001000011110111111111000000100"
str += "0011001000011111110011110111111001001111001000011110111111111000000100"
str += "0000000000000000111111110000000111110011110001100001110000011001111000"
str += "0000000000000000111111110000000111110011110001100001110000011001111000"
str += "0011111111111110000011001000011000001111000001111000110011011110000100"
str += "0011111111111110000011001000011000001111000001111000110011011110000100"
str += "0011000000000110000011110000000110111111111001100000110000011000000000"
str += "0011001111100110111111110001100001111111001001111111111111111111100100"
str += "0011001111100110111111110001100001111111001001111111111111111111100100"
str += "0011001111100110110011001001111110110011001000000001001111011000011100"
str += "0011001111100110110011001001111110110011001000000001001111011000011100"
str += "0011001111100110110000000110011001000011001111100001110000100000000100"
str += "0011001111100110110000000110011001000011001111100001110000100000000100"
str += "0011000000000110001111001111100110110011111110000111110011100000000100"
str += "0011000000000110001111001111100110110011111110000111110011100000000100"
str += "0011111111111110001111110110000000000011001110000000001100000111111100"
str += "0000000000000000000000000000000000000000000000000000000000000000000000"
str += "0000000000000000000000000000000000000000000000000000000000000000000000"

i = 0
for y in range (0,MAX):
    for x in range (0,MAX):
        if(str[i] == '1'):
            img.putpixel([x,y],(0, 0, 0))
        else:
            img.putpixel([x,y],(255,255,255))
        i = i+1

img.show()
img.save("flag.png")

最终扫码得到隐藏的flag信息


flag{a365b025fa3c58bab9af68e3da850460}

总结

本题为CTF竞赛类中的典型Misc类型的题目，经常会通过将对应字符串或者数值进行隐藏图片载体中，需要对图片的RGB、后缀、字符串信息、位平面等进行分析和尝试修改，flag往往就藏在这其中。

兵者，诡道也，真真假假，虚虚实实。没有人可以规定flag应该在哪里，不应该在哪里，不是吗？😎😂

Misc-机密信息(Write_up)

题目信息

技术要点

解题思路

总结