[原创]2022DASCTF Apr X FATE 防疫挑战赛-Reverse-奇怪的交易-CTF对抗-看雪-安全社区|安全招聘|kanxue.com

[原创]2022DASCTF Apr X FATE 防疫挑战赛-Reverse-奇怪的交易
发表于: 2022-7-18 09:35 10085
[原创]2022DASCTF Apr X FATE 防疫挑战赛-Reverse-奇怪的交易

XUNVVAY
2022-7-18 09:35
10085
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
5.使用tinyaes对cup.pyc.encrypted进行解密，得到解密后的pyc
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：
反编译奇怪的交易.py文件源码：（源码不完整）
7.对密文进行解密，得到flag变换后的明文
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。
工具来源：
https://github.com/extremecoders-re/pyinstxtractor
https://tool.lu/pyc/
https://github.com/pablocelayes/rsa-wiener-attack
#!/usr/bin/env python

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

key = '0000000000000tea'
#!/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()
#!/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()
#!/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
#!/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
#!/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
#!/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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

        0x647327833ACFEF1F9C83E74E171FC300FA347D4A6769476C33DA82C95120ACB38B62B33D429206FE6E9BB0BB7AB748A1036971BEA36EC47130B749C1C9FF6FE03D0F7D9FC5346EB0E575BDFA6C530AA57CD676894FC080D2DD049AB59625F4B9C78BCFD95CDCD2793E440E26E189D251121CB6EB177FEDB596409034E8B0C5BBD9BD9342235DBB226C9170EFE347FF0FD2CFF9A1F7B647CC83E4D8F005FD7125A89251C768AFE70BDD54B88116814D5030F499BCAC4673CCCC342FB4B6AC58EA5A64546DC25912B6C430529F6A7F449FD96536DE269D1A1B015A4AC6B6E46EE19DCE8143726A6503E290E4BAE6BD78319B5878981F6CFFDB3B818209341FD68B]

    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)

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