BUUCTF:[MRCTF2020]pyFlag

题目来源:https://buuoj.cn/challenges#[MRCTF2020]pyFlag

题目给了三张jpg

010打开发现每张jpg文件尾附了zip的一部分

将他们合并 得到zip

zip加密 暴力破解 得到密码:1234

得到一个hint和flag.txt

官方脚本

#!/usr/bin/env python

import base64
import re

def baseDec(text,type):
    if type == 1:
        return base64.b16decode(text)
    elif type == 2:
        return base64.b32decode(text)
    elif type == 3:
        return base64.b64decode(text)
    elif type == 4:
        return base64.b85decode(text)
    else:
        pass

def detect(text):
    try:
        if re.match("^[0-9A-F=]+$",text.decode()) is not None:
            return 1
    except:
        pass
    
    try:
        if re.match("^[A-Z2-7=]+$",text.decode()) is not None:
            return 2
    except:
        pass

    try:
        if re.match("^[A-Za-z0-9+/=]+$",text.decode()) is not None:
            return 3
    except:
        pass
    
    return 4

def autoDec(text):
    while True:
        if b"MRCTF{" in text:
            print("\n"+text.decode())
            break

        code = detect(text)
        text = baseDec(text,code)

with open("flag.txt",'rb') as f:
    flag = f.read()

autoDec(flag)

得到flag{Y0u_Are_4_p3rFect_dec0der}

参考:https://blog.csdn.net/mochu7777777/article/details/109829704