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CTF对抗-2022DASCTF Apr X FATE 防疫挑战赛-Reverse-奇怪的交易

推荐 原创

周杰伦

文章分类 Pwn HarmonyOS Web安全 软件逆向 阅读数 : 613 阅读时长 : 9分钟

2022DASCTF Apr X FATE 防疫挑战赛-Reverse-奇怪的交易

那天做了挺久，最后终于搞出来了:)
1.放到ida中判断出该文件使用pyinstaller打包
2.使用pyinstxtractor对exe进行反编译
3.得到奇怪的交易.pyc和PYZ-00.pyz_extracted文件夹中的pyc文件
4.反编译pyimod00_crypto_key.pyc，得到pyc.encrypted加密密钥为0000000000000tea

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#!/usr/bin/env python
key = '0000000000000tea'

5.使用tinyaes对cup.pyc.encrypted进行解密，得到解密后的pyc

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#!/usr/bin/env python3
import tinyaes
import zlib
CRYPT_BLOCK_SIZE = 16
 
# key obtained from pyimod00_crypto_key
key = bytes( '0000000000000tea' , 'utf-8' )
 
inf = open ( 'cup.pyc.encrypted' , 'rb' ) # encrypted file input
outf = open ( 'cup310.pyc' , 'wb' ) # output file
 
# Initialization vector
iv = inf.read(CRYPT_BLOCK_SIZE)
 
cipher = tinyaes.AES(key, iv)
 
# Decrypt and decompress
plaintext = zlib.decompress(cipher.CTR_xcrypt_buffer(inf.read()))
 
# Write pyc header
# The header below is for Python 3.10
outf.write(b '\x6f\x0d\x0d\x0a\0\0\0\0\0\0\0\0\0\0\0\0' )
# Write decrypted data
outf.write(plaintext)
 
inf.close()
outf.close()

6.反编译奇怪的交易.pyc和cup.pyc，得到main函数和encrypt函数。判断出加密函数为xxtea加密算法，得到加密的密文和密钥。
main函数不完整，但是猜测bbb就是xxtea加密后的密文，[54,54,54,54]就是密钥。
cup.py文件源码：

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#!/usr/bin/env python
# visit https://tool.lu/pyc/ for more information
import libnum
from ctypes import *
 
def MX(z, y, total, key, p, e):
     temp1 = (z.value >> 5 ^ y.value << 2 ) + (y.value >> 3 ^ z.value << 4 )
     temp2 = (total.value ^ y.value) + (key[p & 3 ^ e.value] ^ z.value)
     return c_uint32(temp1 ^ temp2)
 
 
def encrypt(v, k, z):
     delte = 0x9E3779B9L
     ᘛ = 6 + 52 / / v
     total = c_uint32( 0 )
     ᘔ = c_uint32(k[v - 1 ])
     ᘕ = c_uint32( 0 )
     if ᘛ > 0 :
         total.value + = delte
         ᘕ.value = total.value >> 2 & 3
         ᘚ = c_uint32(k[ 0 ])
         k[v - 1 ] = c_uint32(k[v - 1 ] + MX(ᘔ, ᘚ, total, z, v - 1 , ᘕ).value).value
         ᘔ.value = k[v - 1 ]
         ᘛ - = 1
         if not ᘛ > 0 :
             return k

反编译奇怪的交易.py文件源码：（源码不完整）

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#!/usr/bin/env python
# visit https://tool.lu/pyc/ for more information
from cup import *
if __name__ = = '__main__' :
     flag = input ( '\xe8\xaf\xb7\xe8\xbe\x93\xe5\x85\xa5flag' )
     pub_key = [
         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
     m = libnum.s2n(flag)
     c = str ( pow (m, pub_key[ 1 ], pub_key[ 0 ]))
     aaa = []
     bbb = [
         0xD28ED952 ,
         1472742623 ,
         0xD91BA938 ,
         0xF9F3BD2D ,
         0x8EF8E43D ,
         617653972 ,
         1474514999 ,
         1471783658 ,
         1012864704 ,
         0xD7821910 ,
         993855884 ,
         438456717 ,
         0xC83555B7 ,
         0xE8DFF468 ,
         198959101 ,
         0xC5B84FEB ,
         0xD9F837C6 ,
         613157871 ,
         0x8EFA4EDD ,
         97286225 ,
         0x8B4B608C ,
         1471645170 ,
         0xC0B62792 ,
         583597118 ,
         0xAAB1C22D ,
         0xBDB9C266 ,
         1384330715 ,
         0xAE9F9816 ,
         0xD1F40B3C ,
         0x8206DDC3 ,
         0xC4E0BADC ,
         0xE407BD26 ,
         145643141 ,
         0x8016C6A5 ,
         0xAF4AB9D3 ,
         506798154 ,
         994590281 ,
         0x85082A0B ,
         0xCA0BC95A ,
         0xA7BE567C ,
         1105937096 ,
         1789727804 ,
         0xDFEFB591 ,
         0x93346B38 ,
         1162286478 ,
         680814033 ,
         0xAEE1A7A2 ,
         0x80E574AE ,
         0xF154F55F ,
         2121620700 ,
         0xFCBDA653 ,
         0x8E902444 ,
         0xCA742E12 ,
         0xB8424071 ,
         0xB4B15EC2 ,
         0x943BFA09 ,
         0xBC97CD93 ,
         1285603712 ,
         798920280 ,
         0x8B58328F ,
         0xF9822360 ,
         0xD1FD15EE ,
         1077514121 ,
         1436444106 ,
         0xA2D6C17E ,
         1507202797 ,
         500756149 ,
         198754565 ,
         0x8E014807 ,
         880454148 ,
         1970517398 ,
         0xBFC6EE25 ,
         1161840191 ,
         560498076 ,
         1782600856 ,
         0x9D93FEBE ,
         1285196205 ,
         788797746 ,
         1195724574 ,
         0xF2174A07 ,
         103427523 ,
         0x952BFE83 ,
         0xF730AC4C ,
         617564657 ,
         978211984 ,
         1781482121 ,
         0x8379D23A ,
         0xEAD737EE ,
         0xE41555FB ,
         659557668 ,
         0x99F3B244 ,
         1561884856 ,
         0x842C31A4 ,
         1189296962 ,
         169145316 ,
         0xA5CE044C ,
         1323893433 ,
         824667876 ,
         408202876 ,
         0xE0178482 ,
         0xF412BBBC ,
         1508996065 ,
         162419237 ,
         0xDE740B00 ,
         0xB7CB64FD ,
         0xEBCADB1F ,
         0x8EAE2326 ,
         0x933C216C ,
         0xD7D1F649 ,
         481927014 ,
         0xA448AC16 ,
         0xBC082807 ,
         1261069441 ,
         2063238535 ,
         0x8474A61D ,
         101459755 ,
         0xBC5654D1 ,
         1721190841 ,
         1078395785 ,
         176506553 ,
         0xD3C5280F ,
         1566142515 ,
         1938949000 ,
         1499289517 ,
         0xC59872F8 ,
         829714860 ,
         0xE51502A2 ,
         952932374 ,
         1283577465 ,
         2045007203 ,
         0xEBE6A798 ,
         0xE09575CD ,
         0xADDF4157 ,
         0xC4770191 ,
         482297421 ,
         1734231412 ,
         0xDAC71054 ,
         0x99807E43 ,
         0xA88D74B1 ,
         0xCB77E028 ,
         1533519803 ,
         0xEEEBC3B6 ,
         0xE7E680E5 ,
         272960248 ,
         317508587 ,
         0xC4B10CDC ,
         0x91776399 ,
         27470488 ,
         1666674386 ,
         1737927609 ,
         750987808 ,
         0x8E364D8F ,
         0xA0985A77 ,
         562925334 ,
         0x837D6DC3 ]
     i = 0
     if i < len (c):
         ᘞ = 0
         aaa.append(ᘞ)
         i + = 4
         if not i < en(c):
             ᘝ = [
                 54 ,
                 54 ,
                 54 ,
                 54 ]
             ccc = len (aaa)
             res = encrypt(ccc, aaa, ᘝ)
             if aaa = = bbb:
                 print ( 'You are right!' )
                 input ('')
                 quit()
 
print ( 'Why not drink a cup of tea and have a rest?' )
continue

7.对密文进行解密，得到flag变换后的明文

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from ctypes import *
def MX(z, y, total, key, p, e):
     temp1 = (z.value>> 5 ^ y.value<< 2 ) + (y.value>> 3 ^ z.value<< 4 )
     temp2 = (total.value ^ y.value) + (key[(p& 3 ) ^ e.value] ^ z.value)
     return c_uint32(temp1 ^ temp2)
 
def decrypt(n, v, key):
     delta = 0x9e3779b9
     rounds = 6 + 52 / / n
 
     total = c_uint32(rounds * delta)
     y = c_uint32(v[ 0 ])
     e = c_uint32( 0 )
 
     while rounds > 0 :
         e.value = (total.value >> 2 ) & 3
         for p in range (n - 1 , 0 , - 1 ):
             z = c_uint32(v[p - 1 ])
             v[p] = c_uint32((v[p] - MX(z,y,total,key,p,e).value)).value
             y.value = v[p]
         z = c_uint32(v[n - 1 ]) 
         v[ 0 ] = c_uint32(v[ 0 ] - MX(z,y,total,key, 0 ,e).value).value
         y.value = v[ 0 ] 
         total.value - = delta
         rounds - = 1
 
     return v
 
import binascii
if __name__ = = "__main__" :
     v = [
         0xD28ED952 ,
         1472742623 ,
         0xD91BA938 ,
         0xF9F3BD2D ,
         0x8EF8E43D ,
         617653972 ,
         1474514999 ,
         1471783658 ,
         1012864704 ,
         0xD7821910 ,
         993855884 ,
         438456717 ,
         0xC83555B7 ,
         0xE8DFF468 ,
         198959101 ,
         0xC5B84FEB ,
         0xD9F837C6 ,
         613157871 ,
         0x8EFA4EDD ,
         97286225 ,
         0x8B4B608C ,
         1471645170 ,
         0xC0B62792 ,
         583597118 ,
         0xAAB1C22D ,
         0xBDB9C266 ,
         1384330715 ,
         0xAE9F9816 ,
         0xD1F40B3C ,
         0x8206DDC3 ,
         0xC4E0BADC ,
         0xE407BD26 ,
         145643141 ,
         0x8016C6A5 ,
         0xAF4AB9D3 ,
         506798154 ,
         994590281 ,
         0x85082A0B ,
         0xCA0BC95A ,
         0xA7BE567C ,
         1105937096 ,
         1789727804 ,
         0xDFEFB591 ,
         0x93346B38 ,
         1162286478 ,
         680814033 ,
         0xAEE1A7A2 ,
         0x80E574AE ,
         0xF154F55F ,
         2121620700 ,
         0xFCBDA653 ,
         0x8E902444 ,
         0xCA742E12 ,
         0xB8424071 ,
         0xB4B15EC2 ,
         0x943BFA09 ,
         0xBC97CD93 ,
         1285603712 ,
         798920280 ,
         0x8B58328F ,
         0xF9822360 ,
         0xD1FD15EE ,
         1077514121 ,
         1436444106 ,
         0xA2D6C17E ,
         1507202797 ,
         500756149 ,
         198754565 ,
         0x8E014807 ,
         880454148 ,
         1970517398 ,
         0xBFC6EE25 ,
         1161840191 ,
         560498076 ,
         1782600856 ,
         0x9D93FEBE ,
         1285196205 ,
         788797746 ,
         1195724574 ,
         0xF2174A07 ,
         103427523 ,
         0x952BFE83 ,
         0xF730AC4C ,
         617564657 ,
         978211984 ,
         1781482121 ,
         0x8379D23A ,
         0xEAD737EE ,
         0xE41555FB ,
         659557668 ,
         0x99F3B244 ,
         1561884856 ,
         0x842C31A4 ,
         1189296962 ,
         169145316 ,
         0xA5CE044C ,
         1323893433 ,
         824667876 ,
         408202876 ,
         0xE0178482 ,
         0xF412BBBC ,
         1508996065 ,
         162419237 ,
         0xDE740B00 ,
         0xB7CB64FD ,
         0xEBCADB1F ,
         0x8EAE2326 ,
         0x933C216C ,
         0xD7D1F649 ,
         481927014 ,
         0xA448AC16 ,
         0xBC082807 ,
         1261069441 ,
         2063238535 ,
         0x8474A61D ,
         101459755 ,
         0xBC5654D1 ,
         1721190841 ,
         1078395785 ,
         176506553 ,
         0xD3C5280F ,
         1566142515 ,
         1938949000 ,
         1499289517 ,
         0xC59872F8 ,
         829714860 ,
         0xE51502A2 ,
         952932374 ,
         1283577465 ,
         2045007203 ,
         0xEBE6A798 ,
         0xE09575CD ,
         0xADDF4157 ,
         0xC4770191 ,
         482297421 ,
         1734231412 ,
         0xDAC71054 ,
         0x99807E43 ,
         0xA88D74B1 ,
         0xCB77E028 ,
         1533519803 ,
         0xEEEBC3B6 ,
         0xE7E680E5 ,
         272960248 ,
         317508587 ,
         0xC4B10CDC ,
         0x91776399 ,
         27470488 ,
         1666674386 ,
         1737927609 ,
         750987808 ,
         0x8E364D8F ,
         0xA0985A77 ,
         562925334 ,
         0x837D6DC3 ]
 
     k = [ 54 ] * 4
     n = len (v)
 
     res = decrypt(n, v, k)
     res1 = ''
     for i in res:
         j = hex (i)[ 2 :]
         #print ( binascii.unhexlify(i))
         print ( binascii.a2b_hex(j))
         res1 + = j
     #res1 = bytes(res1)
     print (res1)
     print ( binascii.a2b_hex(res1) )

8.根据代码flag = str( pow(m, pub_key[1], pub_key[0]))等价与求RSA解密后明文。通过pub_key的值发现e和n非常大且十分接近，那么可以利用RSA的维纳攻击直接解出flag。

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from Crypto.Util.number import *
from gmpy2 import *
from RSAwienerHacker import *
import libnum
n = 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
e = 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
c = 10610336534759505889607399322387179316771488492347274741918862678692508953185876570981227584004676580623553664818853686933004290078153620168054665086468417541382824708104480882577200529822968531743002301934310349005341104696887943182074473298650903541494918266823037984054778903666406545980557074219162536057146090758158128189406073809226361445046225524917089434897957301396534515964547462425719205819342172669899546965221084098690893672595962129879041507903210851706793788311452973769358455761907303633956322972510500253009083922781934406731633755418753858930476576720874219359466503538931371444470303193503733920039
 
d = hack_RSA(e,n)
flag = long_to_bytes( pow (c,d,n))
print (flag)
 
b 'flag{You_Need_Some_Tea}'

工具来源：
https://github.com/extremecoders-re/pyinstxtractor
https://tool.lu/pyc/
https://github.com/pablocelayes/rsa-wiener-attack



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