[N0wayback 2023春节红包题] happyGame python反编译

这个反编译的比较深

一，从附件的图标看是python打包的exe文件，先用pyinstxtractor.py 解包

生成的文件在main.exe_extracted目录下，在这里边找到main

二，把main改名为pyc然后加上头

这个头从包里找一个带头的pyc文件（这里用的_boot文件）把E3前边的16字节插进来

三，用uncompyle6反编译，生成mai.py

N0WayBack\春节红包题\Re_rabbit_Game>uncompyle6 main.pyc > main.py 

四，打开main.py查看流程，这里需要运行114514次magic_s()每次会进行一个LCG处理

                            if self.score < 114514:self.magic_s()self.score += 1

LCG

    def magic_s(self):p = 16045690984230472446a = 114514b = 1919810self.magic = (a * self.magic + b) % p

 

然后会打印解密的flag

    def print_flag(self):key = str(self.magic)[:16]enc = AES.new(key.encode(), AES.MODE_ECB)flag = enc.decrypt(self.FLAG)print(flag)self.draw_text(flag, 22, WHITE, WIDTH / 2, HEIGHT / 2)self.draw_text('Happy 2023!!!!!', 22, WHITE, WIDTH / 2, HEIGHT / 2 - 40)

五，这里要对FLAG进行AES解密，key在secret里

from secret import flag

问大姥，这个自己写导入的secret都在 PYZ-00目录里，文件是经过aes加密和zlib压缩

PYZ-00.pyz_extracted

 六，用网上的脚本进行解密解压，生成secret.pyc文件

import glob
import zlib
import tinyaes
from pathlib import PathCRYPT_BLOCK_SIZE = 16# key obtained from pyimod00_crypto_key
key = bytes('0000000000r4bb1t', 'utf-8')for p in ['secret.pyc.encrypted']: #Path("PYZ-00.pyz_extracted").glob("**/*.pyc.encrypted"):inf = open(p, 'rb') # encrypted file inputoutf = open('secret.py', 'wb') # output file# Initialization vectoriv = inf.read(CRYPT_BLOCK_SIZE)cipher = tinyaes.AES(key, iv)# Decrypt and decompressplaintext = zlib.decompress(cipher.CTR_xcrypt_buffer(inf.read()))# Write pyc header# The header below is for Python 3.8outf.write(b'\x55\x0d\x0d\x0a\0\0\0\0\0\0\0\0\0\0\0\0')# Write decrypted dataoutf.write(plaintext)inf.close()outf.close()# Delete .pyc.encrypted file#p.unlink()

这里的aes用的key在pyimod00_crypto_key 文件里，这也是个pyc文件，可以反编译也可以直接看，拿到key

七，得到flag后对，编写代码利用原用函数解密

from Crypto.Cipher import AES FLAG = bytes.fromhex('17e8fb647b4b10cc8182f0f76649f08bd2d33eacb5fa4ca865d99062f8d0b4c479d7d2328081121536c26c6a4150efb5')magic = 0
def magic_s():global magic p = 16045690984230472446a = 114514b = 1919810magic = (a * magic + b) % pdef print_flag():key = str(magic)[:16]enc = AES.new(key.encode(), AES.MODE_ECB)flag = enc.decrypt(FLAG)print(flag)for _ in range(114514):magic_s()print_flag()
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